right national cable satellite corp. 2014] [captioning performed by the national captioning institute, which is responsible for its caption content and accuracy. visit ncicap.org] >> and gentlemen in england now abed chauffeuring themselves accursed movie were not here -- they'll think themselves accursed many were not here. >> one drop of toronto from country's-- blood drawn from thy country's bosom. >> you have to go with the word in which similar burden dude word you pause and linger over a longer phrase and keep going. he is using the rhythm of the

language so that you can take language and put it into high gear and then slow down. that is something shakespeare lets you do if you are a politician. >> the night, the night. parting is such sweet sorrow. >> iowa state university professor thomas leslie talks about the changes in 19th-century architecture design and technology. new materials and foundation methods allowed buildings to be built taller and incorporate more glass to but in more light to interior spaces. this class is an hour and a half. professor leslie: let's get started. good afternoon to everyone and our expanded classroom today. i want to start quickly with where we are in the course and how this intersects with american history in particular.

we have been looking at the history of building construction in the west, and we have gotten to the point where we have it developed a fair amount of building structures. we have a couple of new materials we are working with -- iron and also glass. finally, we have this conception that we talked about last week from the french theorist who is thinking about iron and iron framing in particular, realizing that late in his career that there is a possibility of having a metal frame that is self structured with a shell around it made of metal masonry. that may be self-supporting. we will see how that is developed in a particular place, in a particularly robust way. this intersects with a strong

and robust economic progress in a location that is fairly new for us in this course -- that is the united states, the americas. american history to this point has been one of west word was formed -- wasestward expansion. the railroad is a fairly new but liberating device. and in the late 19th century in particular, the american economy is coming the place where the industrial revolution really gets transferred from great britain in particular. chicago is where a lot of this comes together, and where we see the most interesting example of how the industrial revolution and the economic influence it had comes together and creates a new building type, the skyscraper. it is difficult to say where the first skyscraper is, chicago partisans will tell you of course that it is in chicago. new york architects will tell you something very different. but the case in chicago is different from anywhere else in the country.

so almost anyone can tell you that chicago architecture, chicago skyscrapers in particular, related to this one quote from louis sullivan -- form follows function. throughout the course we have taken this is one of our starting points and talk about the way that this doesn't get the whole picture, that buildings are not only about function, not only about how they perform. we look at louis sullivan's business partner until 1895, and his reaction to sullivan's quote. adler pointed out that if it was as simple as form follows function, every building built all the way to the romans would look exactly the same. and we know that is not true. we know that early skyscrapers look very different for instance from the sears tower, or from the burj khalifa. even though their functions are

the same, increasing the amount of the buildable area on the spot of land. adler points out that in his words, function and environment determine form. what he means by environment is not climate, he meets environment in terms of the kind of context in which holdings happen. -- buildings happen. in particular, adler thinks about the available materials and techniques that one has to build with. so a skyscraper in roman times a five-story apartment house is going to be determined in large part by the dialogue between the function of piling floors on top of one another and the available material, relatively simple brick. a skyscraper built in the late 19th century, when there is iron when there is glass, when there are elevators in particular, will look very , very different. in chicago in particular, we see

a robust example of this negotiation between a function and this palliative material that adler is talking about. the skyscraper is pretty much an american phenomenon. there are precedents, of course. there are tall commercial buildings in britain, we will look at mill construction. in particular. it is the real estate speculation that leads to a new type of machine to make the land pay, as an architect one said. the technology involved in skyscrapers meant that the building was sort of capped at 5-6 stories through the 1850's. the reason for this is that if you were trying to rent out space in a tall building, you were limited by the number of stairs people were willing to climb. this was less so in mill construction, where you sound were not so -- where you were not so worried about your worker's comfort.

but when you read out a space rent out-- rent out a space you need that accessible easily. when elevators became normal there were still structural limitations that remain. particularly the limits of brick and timber kept buildings to under 7-8 stories through the 1780's. parallel to the problem of height is the problem of illumination. these buildings up to the 1880's are mostly illuminated by daylight or by illuminating gas. in fact, as late as 1990, we see daniel burnham's partner and lead designer saying that within a tall office building, any does -- any space which is not illuminated by daylight is in his words, "non productive." he -- productive." he calls it a great architectural problem, the design of a chicago office building. the elementary question was how how to arrange the building so

that every foot in it should be perfectly lighted by the sun and not electricity, and all spaces which would otherwise be dark be thrown out. we've will see examples of what this means to planning and layout in a minute. the skyscraper is a new building type, but it relies on advances that have gone on in the early 19th century. and in particular, on mill construction, this way of building factories that involved iron framing and masonry walls. the key thing we will see is how mill construction evolves, how it gets changed and impacted by the need to eliminate spaces by -- illuminate spaces by sunlight. we looked last week at early british mills and in particular those that used cast iron beams whose shape follows the ideal shape, the ideal loading diagram , the ideal moment diagram of a

structural member in bending. this is only possible in cast-iron, in wrought iron which is rolled, the shape would have to be the same from end to end. this replaced a lot of the brick gone into early construction with much more slender cast iron. the problem that remain the -- renamed -- remained with these is the problem of lateral resistance, how these buildings stood up against wind. cast iron is good against gravity, but against wind it is a loose structural system. therefore, the british mills had heavy masonry walls around them. it is good for structures, not so good for illumination. we will watch as this problem slowly gets solved in chicago. there are a number of what we might call proto-skyscrapers that are built in the 1870's and 1880's which are mill

construction dressed up in particular clothing. in particular, the work of george post, who is a new york architect, who designs buildings in 5-7 stories in manhattan. as you can see from the construction photo, they are essentially cast-iron construction wraps in -- wrapped in a masonry jacket. the trading floor from the potus exchange, -- produce exchange, this has cast-iron beams which are then closed with a near -- neoclassical dress. what is essentially happening is similar construction to that of the british mills, cast-iron columns, wrought iron beams, and masonry walls used to handle the lateral bracing. with these proto-skyscrapers with mill construction already there, with most of the technology needed to build tall buildings, what happens to chicago that makes it special?

what makes this building of a particular height? there is a motivating cause in chicago that has to do with its peculiar geography and economics and of the transportation hub that emerges there. this results in a kind of drive for more commercial real estate, which in turn drives speculation. it is often money coming from boston or new york and philadelphia into chicago, that is investing in new skyscrapers without the owners really seeing the building, buying and trading land and building in the downtown area. the technology supports this. always towards the ends of making more money, right, piling floors on one another, and particularly making those forced -- floors usable. reducing the footprint of the structure on the exterior and trying to bring in more and more daylight into the interior spaces. we will see a couple of early rounds of technical advances

that involve elevators that had cast-iron facades. there is a reason of that chicago becomes a world center for fireproof innovation in the 1870's. and as that happens, see that these masonry walls that surrounded british mills and proto-skyscrapers begin to become what we might call skeletalized. they begin to morph from walls interferes, which opens up the external to bring more daylight in. perhaps the greatest confirmation occurs in the late 1890's, when steel replaces wrought iron as a building material. we will look at what that means in terms of the building's skin. what happens when the exterior walls of a building are no longer charged with supporting the structure against either wind or gravity, and how does

that free the exterior up to bring in even more daylight? there are a couple of peculiar things that happened in chicago in the 1890's that influenced the way that skyscrapers develop. we look at those. and then finally, we will talk about influence and how the model of the chicago skyscraper influenced technically inclined architecture in the 20th century. so we'll start with the city itself. and in particular, chicago's geography and how this impacted building in the loop and how the way people thought about buildings in particular. to do this, i will rely on an argument put forth by william cowan in a 1992 book, "dangerous -- "nature's metropolis" that argued that chicago's importance had to do with the midwest position it existed in. in particular its position near the shore of lake michigan.

chicago was founded in part because it existed near the port near the end of the chicago river and illinois river. with a couple miles walk, you could get into water system that ended up in the atlantic, to a water system that could end up in the gulf of mexico. this established chicago at the -- as a trading post and by the 1800s it had established the city based on the exchange of goods with the market out east. when the railroads came along in the 1850's, chicago's position at the southern end of lake michigan maybe had even more to do with this growth. if you are trying to get produce from, for example, iowa to new york, you have to go around the southern end of lake michigan. railroads from the west and railroads from the east both came to chicago, but

importantly, very few links were made between the two. goods were unloaded in chicago loaded it back onto trains headed east, and in this field the market for speculation. you could bet on corn futures. you can sell to a market out east. you can make money in chicago based on what people are growing in iowa or what people are buying in new york. you can be a sort of middle man. as conan points out, the economic sphere includes the entire midwest. in 1881 in central iowa, you would have thought of yourself as a far western suburb of chicago. most of what happens here economically had some thing to do with trading or banking or financing in the city. and with that kind of huge area of land suitable profit from and control -- land to profit from

and control economically, chicago became the hottest real estate market in the country. speculators invested not only in the goods from the midwest being traded there, but they wanted to speculate on real estate from the city itself. through the 1870's and early 1880's, most of chicago's architecture was very pragmatic. a lot of it had to do with trade on the river. this is the chicago river just used of michigan avenue stop it has -- just east of michigan avenue. it has changed a bit since then. you can see that is iowa's furthest part that it covered, the farthest part of the state being sold as lumber to markets run the city and also further east. grain elevators also housed the produced that came from the upper midwest, they put it on ships or trains headed east. most importantly, this relatively cheap construction that first gave offices for

bankers, for traders, for speculators and later became a commodity itself. real estate was in office buildings that could be bought and traded just like coin from -- corn from iowa that could be bought and treated. these buildings are relatively simple. they are mostly timber and iron framed. similar to mill construction but one difference here and seeing the effort to bring daylight in, to make the windows , particularly on the street fronts as large as possible. therefore, to make the office spaces inside as attractive as possible and as lettable as possible. even through the 1870's and 1880's, chicago buildings chicago commercial real estate was generally 5-8 stories. nothing about that. in part because elevators are still slow, but mostly because there are still structural problems with food -- with the cast iron and timber framing. that was being used.

this is what enabled to view building boom in the city. -- enabled the first building boom in the city. elevators in particular allowed offices on the fifth or sixth floor to be just as valuable as offices on the first floor. in 1853, this is document it by a historian that gave people the security of knowing that this mechanism in the building lifted things, the height was unprecedented in commercial construction and would be relatively safe. in the center, you see otis himself demonstrating the safety break. one of the assistance is cutting the cord that holds the elevator frame up. people are looking in horror expecting otis to die, but the spring-loaded arms are catching the falls. he looks completely unruffled. this was a major advance. elevator disasters were fairly

common, and they were used almost entirely for freight through the 1850's. it is otis' invention of this safety device makes it commercially viable. we see the first use for people and for tenants in the 1850's. this demonstration is taking place in new york's crystal palace, built in 1854, the immediate heir of the london crystal palace that we discussed earlier. chicago also imports cast iron from new york. there are cast-iron facades that are built throughout the loop in the 1850's. there are a few that remain from the post-fire area, including the bergoff downtown, a famous restaurant. this row of loft building, where you can see the fronts on the first floor have been retrofitted. you can see the difference between what brick gives you as a facade material versus the advantages of cast-iron, which

is much stronger and therefore lets you accomplish the same structural task with a smaller area. on the ground floor, you can see that if you are a shopfront owner, you are much happier with the exposure that you get. you also get a fair amount of daylight through. this will become a constant theme, replacing the heavy break -- heavy brick on the exteriors with a much thinner and efficient cast iron. cast iron is sold as a fireproof material. in 1871, the fire in chicago among other things proves that this is completely untrue -- that cast iron is in fact entirely vulnerable to fire. you can see in this image of the aftermath of the 1871 fire, that there are the remains of cast-iron buildings are scattered throughout the loop. what has happened here are two things -- firstly, the contents of the buildings themselves have burned. the cast iron hasn't ignited, but it has certainly weakened

and then the soft and -- and then softened by the heat of the fires around. as it has weakened, it has collapsed. the second thing that happened was that cast iron was a brittle material. as firefighters tried to put out fires in cast-iron buildings, the sudden quenching of the red-hot cast-iron wood called the structural members to shatter, which would bring down the building around. it destroys another 16 blocks of chicago. there is a real effort in the city to try and reform construction. firstly, to outlaw timber construction in commercial buildings, and secondly to try and find ways to both fireproof cast-iron or to build more efficiently out of brick. in both of these cases, clay becomes the way that these buildings achieve fireproofing. chicago, of course, built on the mouth of a slow-moving river has nothing but clay to build with.

this is lousy for foundation, but fantastic if you are a brick maker. and there are brick industries that spring up around chicago as early as 1830. by the 1850's, brick as a technology has moved well beyond its medieval or ancient origins. and we have a number of machines that not only make brick work -- brick more quickly and reduce the amount of labor involved but press what clay is made up squeezing the water made of it and leading to a much stronger material. we have looked almost from the beginning at brick as a building material, in egyptian and roman times. and we saw that there was a big distinction between brick that was just mud dried with a compressive strength of 3500 180 kg /cm.

pressed brick adds an order of magnitude to the strength of the material. you can see that with hydraulic pressing and a lengthy kiln firing, we have doubled or cost -- or quadrupled the strength of brick yet again. the machines that come online in the 1860's suddenly allow us to achieve the same structural path -- strength with about a quarter of the material. if you graph the progressive height of a typical chicago skyscraper between the great fire and of the great depression what you find that there is a generation of buildings fairly early on that expresses the arrival of these break pressing machines into the city. that thought guys group or height -- that skyscraper heights jump noticeably on average a few stories at a time. the greatest examples is the montauk, built on munro street where first national bank is

now, it was described as the end all of chicago skyscrapers. why would you ever needs to go higher than 10 stories, right? it would not even be the tallest building on its block today. montauk used cast iron and a wrought iron on its exteriors and floors. the exterior and the central core are made out of hydraulic pressed brick that allows you to go up these 10 stories with relatively small dimensions. you can see the problems right away, though. if you are trying to open up large windows on the exterior, brick is heavy. it is not certainly as strong as iron, and therefore your window sizes are very limited. as you go down the building to the ground floor, where you might want to put shops, retail, the self weight of the brick demand larger and larger piers. the floors that have the most brick, the least glass are the

ones at the street level that probably need them the most. you can see that the montauk stands up through the use of sheer walls. the brick is arranged so that north-south and east-west, you have a fairly regular grid of walls that prevent the building from wracking or swaying in the wind at all. very effective but space intensive. the brick takes up a great deal of area. brick, at the end of the day, is heavy, it is slow to build with, and brick layers begin to have a particular reputation of being strkike-prone. they had these unrealistic demands like getting half a day off on saturday from working. and builders architects tend to be reluctant to employ brick than usual. -- more brick than they need to. the more brick you have on-site, the more likely that a strike would delay the construction of your building. there are other solutions that

begin to take these walls and distill them to what we make -- might think of as piers. the same clay that the city builds itself out of in the 1870's and the 1880's is the worst soil to build a heavy skyscraper on. you see solutions to the problems of foundations beginning in the late 1880's. architecture engineers realized that to cope with differential settlement, it is easier if you calculate foundations, if instead of bringing wall foundation stone to the ground you bring isolated footings instead of linear support. this brings forth solutions in stone around 1882. around then, surplus rail iron is used to replace these take, -- big, heavy space pyramids. with what are called grillages.

these are essentially slabs in reverse that take loads from an individual column or pier and spread them out over soil below. later on we will see solutions like friction peersiers, where you are relying on the grip of this wet clay or timber piles. then the problem is finally solved in 1895, concrete in iron columns that run all the way down to bedrock, anywhere between 60-100 feet below the soil. the importance of foundations to the way skyscrapers are built above ground, is that this gets architects to think of structure s not as walls, but as columns. you are more likely to think of the structure above as a grid instead of as a series of walls. we can see the influence of this on some structures in the 1880's. the early work of adler and

sullivan in particular takes the sort of walls that have frustrated efforts at daylighting in the montauk and turn those piers 90 degrees to the street. instead of masonry that appears as a wall, the brick here in the jewelers building reads more like a pier. these brick piers are 3-4 feet deep that go into the building to get the area needed to carry the load. but you can see that they allow very large windows. you are also beginning to see these hybrid facades where some of it is brick, some is cast-iron. the cast-iron allows you a lot more glass to capture daylight from the street in particular. so we have brick piers that begin to respond to this need for daylight in the foundations.

we have another way that clay participates in the skeletalization of the chicago skyscraper. that is that fire and clay terra-cotta in particular, is used as a fireproofing material, both for floors in what you can see here in what is called a hollow arch section -- you can see that the terra-cotta wraps around these four joints that protects it from fire, offers air spaces that take a while to heat up, therefore protecting the vulnerable iron beams from the heat of the fire. you can see too that around the columns, this is a later project so there are steel columns but the terra-cotta forms jackets and insulates them from the heat of the fire, protecting them from softening or melting. also protecting them when firefighters arrived and douse

the structure with water. this is from the "fireproof structure" from about 10 years ago. these are solutions that rely on terra-cotta, abundant in chicago, a city built on clay. this becomes a way not only to protect the internal structure but also to protect the external structure. around the end of the 1870's, we start to see what we might loosely call the skeleton frame. right? the iron frame developing as a response to both concerns about structure, concerns about fireproofing, and concerns about daylighting. jennings a well-known engineer, begins to develop this in a warehouse building, called the lighter store. the iron columns are essentially placed next to large brick

piers. the brick piers are still arranged parallel to the street front, so they are taking up the most possible facade. but now they are helped in their structural task by these iron columns behind them. so they can be smaller, and as a result the windows can be larger. you can see that the spandrals the upstanding from the floor is very low. this is how desperate architects are to bring daylight into their interiors. a few years later, maybe slightly better-known, this is jimmy's home insurance building. a tall commercial building. and jennings says that his charge in this case was an insurance company that literally told him that the need was for the best possible lighting in the interior of the offices. you can see that he has taken the formula from the first lighter building and sort of

moved it along one step. he has embedded the cast-iron into the brick piers. now they are literally a structural hybrid. the iron is carrying some of the weight, the brick is carrying some of the weight. there is controversy about this. in the 1890's this is claimed as being the first ever skyscraper. that is a claim that i think is not even wrong. it's impossible to think of something like the first skyscraper in such an evolutionary process. the reality, as a student of mine a few years ago suggests in this reconstruction, is that rather than thinking of the brick as just fireproofing, as some scholars have, the brick is really doing some of the structural work, and the cast-iron is doing some of the work. it is literally a hybrid structure, just like we think of reinforced concrete today. you can see the blue is all caps -- cast iron, the blue is all

-- the green is all wrought iron. that is to carry the gravity load and some of the lateral loads. this is a tall enough building that wind loads are significant. and without an adequate lateral bracing system, the building will sway, the building will wrack, doors will not open, and overtime at the structure will loosen up. there are a couple different ways that jenny is handling this. on the edges of the lot, he still has masonry sheer walls that are doing a lot of the work of resisting the wind load. this detailed the cast-iron columns embedded in masonry is also capable of bcarrying a certain amount of bending load, of wind load. that will assist the building in standing up against any lateral forces. very much a hybrid structure. maybe a sort of proto-skeleton frame, but definitely still

reliant on masonry for a lot of the gravity load. we see a similar solution on the rookery, which is just about as contemporary with home insurance right across the street. this one is still there, and kind of immaculately restored. it used iron and brick in the structure. there is an exterior skin of all masonry. and and interior structure that is all cast iron columns. importantly, there are also cast-iron columns wrapped very tightly with terra-cotta fireproofing on this interior. if you remember ruth's comment, that even if you have to throw space away to illuminate the interior of office buildings this is a good example. of that. that is potentially valuable real estate in the middle of the read that has literally -- rookery that has been literally

scooped out so that the inner ring of offices get adequate light. whereas on the exterior, ruth chose to go with these very heavy brick piers. on the interior, you can see that with no one seen from the street, he is happy to go with much thinner proportion. jacket of iron in a way that has two a much different feel than on the exterior. also critical, though, that exterior skin of the masonry is the rookery's primary wind bracing. if the wind blows from left to right, there is enough brick going in one direction or another to keep it stable. we have seen the masonry used as sheer walls to keep the building overwrite -- operate-- upright against wind. the exterior of the building is still largely brick. because we need that much brick to resist the wind load, we are still restricted in the amount of glass we can have. because we would like to get more daylight into those

exterior offices in particular. so one step towards what we would call the modern skeleton structure and hung curtain wall happens in 1899. a building by what is then a young firm which realizes that if you take all of this exterior masonry and turn it 90 degrees to the street, you can take care of all of the gravity loads and all of the wind bracing with a structure that is totally internal. so you can see that the tacoma still relies on cast-iron , cast-iron columns and it has four massive sheer walls, one to give you -- two going north-west, two going east-south. they are particular to the street walls. they create a very lightweight veneer of glass and terra-cotta that hung from the outside.

because it has no structural function, there is no limit to the amount of glass you can put on it. you can see this is an extraordinary amount of glass on the elevation. this is a straight elevation and this is another student project looking at the anatomy of the tacoma's skeleton. you can see ago that -- again that there is cast-iron in a light green, wrought iron in a dark green. and then you see the lightweight terra-cotta and glass skin on the outside. that contrast would be massive sheer walls that set it 90 degrees from the street front that keeps the building of against wind storms. even though it seems advanced, at the time he was criticized quite heavily. there were concerns legitimately expressed in the "tribune" that said that in the first good windstorm, the building would be knocked over, that it was as delicate as a birdcage.

people were not used to seeing this much glass on the facade, with this much structure hidden. if we look at the plan of the tacoma, the brick is still taking up a tremendous amount of space. it is reducing the amount of flexibility we have in offices. and more importantly it is space that can't be rented out. you cannot rent out a brick wall you cann only runs out open floorspace. -- rent out floorspace. they also want to fix the lateral, to find a way to do that that doesn't take up as much space as these massive walls of brick. the answer to that proves to be a small development that we touched on when we looked at iron last week. and that is a particular combination of carbon and iron that results in the material we now call as steel.

everything we have looked at so far has used cast-iron or wrought iron. we talked a little bit about the processes involved in making these two. that cast iron is taking raw pig iron, simply melting it and pouring it into a mold. it has a very high carbon content, relatively, which gives it great compressive strength but also makes it very very brittle. we talk about the more finely controlled wrought iron, which has much less carbon in it. this makes it weaker in compression, but also makes it workable. ductile. you can cut it, you can shave it, you can roll it without melting it, which gives you more opportunities to make more useful structural shapes. the invention of the bessemer process in the 1880's, later called the open hearth process allow you to very finely control the amount of carbon you are producing.

you essentially use the bessemer process to take out all of the carbon, then you come back and put in a very precise about. this lets you hit a sweet spot of carbon percentage that does two things. firstly, it gives you that balance between compressive strength and tensile strength. this lets you make very efficient bending members, very efficient beams. but it also gives you ductility, gives you nearly the strength of cast-iron with the workability of wrought iron. and this makes it a kind of brilliant material if you are trying to make very precise connection. bridge design in the 1880's begins to look at trussing spans, which rely on translation and fixed joints. these truss techniques would be

ideal for bracing skyscrapers against wind. but in cast-iron, the problem is that whatever you get out of the mold is what you get. you cannot come back and drill precisely. you cannot cut cast-iron after it is cool. you have to cast molds where you want them to be. when cast iron cools, it shrinks unpredictably. it twists, and those bolt holes never get where you want them. so the bolt holes need to be oversized, so that you can get it in somewhere. that means that the connections are always loose. if you try to build a wind brace structure out of iron, you find that it is rickety. it moves around too much. eventually the connections loosen and the structure collapses. this was what happened in a bridge disaster in scotland in 1879. it makes engineers nervous about using cast-iron in any structure

where it is being asked to take on the load of the wind. steel's great contribution to the chicago skyscraper and skyscraper friends -- skyscraper frames in general is that it is ductile. it lends itself very easy to riveting. you can take two pieces of steel and melt them on-site. you can drill them at the same time to get a precisely sized hole and then use a hot rivet to attach the two pieces of steel. which as it cools draws the pieces together more tightly. if you look at related connections with steel, like you are seeing on the right, or these examples of ways of achieving wind bracing on the left, you can see intuitively that these are much more stiffer connections than the more

simpler connection that you would get with loosely pinned cast iron connections. it is steel that allows skyscraper frames to be self braced against wind and eliminate need for masonry in a tall building auction. construction. chicago's geography plays a role in being part of steel research and construction. it is located almost between a coalfield in the southern indiana. iron comes from minnesota by boat. chicago becomes the center of the steel industry in north america, along with pittsburgh. again, if you sort of chart the heights of chicago buildings you see this whole generation of structures that sort of leaps up in 1890 after the refining -- the bessemer process. and continues at that height because of building

restrictions, legacy building codes. it leaps up between 15-20 stories for a good henumber of -- good 20 of years. this is the old colony building on south dearborn. that uses a technique called a portal frame. so a giant steel web that literally makes a monolithic connection between the steel columns here and the steel girders there. you can see on the plan at the left that this replaces very sick masonry -- sick masonry -- thick masonry sheer walls with skinny steel elements. you can also see that these elements can be toggled through -- toggled through --

tunneled through, you can build an office within the steel portal frame. that would be the only indication that you have this sheer wall and steel surrounding you. maybe a more direct translation of the railroad bridge is the masonic temple built in 1892 and for five weeks the tallest building in the world. it was quickly surpassed in new york. here, you can see that skill is used not only for its capacity to take tension, the system of tension brought that cover the building, but that this was also a very lightweight system and relatively unobtrusive. the trusses are on that line in the floor plan. you have to be careful where you put doors. it is most common to put a wall. but it gives you much less space and allows you to rent out more floor area. so if we have solved the problem of the self braced frame, iron can handle loads better than brick, steel can handle lateral loads in a much more efficient way than brick. we have managed to take the structural function away from

the exterior skin of the building. what does this now mean for our elevations? remember that the critical thing about building facades in the era is bringing in as much daylight as we can. and so we can imagine there will be a push to try to take advantage of all of this newfound space on the building exteriors. and in fact, this is what we see. even in buildings that have a relatively conservative wind bracing scheme, like the pontiac of 1891. this is by the same architecture firm that designed the takoma. you can see there is a similar approach to wind bracing in up -down on the screen. actually east-west on site. that sheer wall takes all of the wind load in the short direction and the multiple number of columns into the other direction handle the wind load in that direction. all of the structure is pulled in from the exterior's skin.

you can see that they take advantage of this by developing these cantilevered windows made of brick and terra-cotta, so still relatively heavy to our eyes, but offering a huge amount of window glass and their late -- and daylight to the interior. more interestingly is this building, designed in 1885 construction continues until 1892. this is usually thought of as the paragon of brick construction. the tallest brick skyscraper in the world. and that is certainly true. you can see it presents some of the inherent problems in masonry construction. if you look closely, you can see that the walls get much thicker as you get closer to the base. six feet thick on the ground floor. this presents all source of problems too in terms of foundation. if you walk into the building

from the north end, you take a s -- is or two down. -- a step or two down. the clay sunk further into the ground that its engineers had planned on. while the building uses masonry for the gravity structure and certainly has these sheer walls that brace against wind laterally. if you look only at the masonry doing the actual structural work, what you find is that is monolithic brick skin offers help in two ways. some of the masonry is doing the work of holding the building up, staying the building against wind, and some of the masonry on these bay windows and between the windows that appear to be punched through the wall -- this is simply self-supporting brick. brick that is doing nothing structurally. all it is doing is cladding, maintaining the integrity of the exterior skin. john ruth, the designer, chose to detail the building which

causes us to read it as this monolithic brick mass. but as this student project shows, the brick is doing two things. there is some brick that is structural come, some that is cladding. or, in the terminology of the day, the near -- veneer. this was challenged by the improvement in the production of plate glass. we would like at the time to design a building that brings in as much daylight as possible, to have as little brick on the outside as we posit we can. through the 1880's, some production techniques lead to a really rapid implosion of glass prices through the 1890's. that is a kind of national trend. but there is a geographical peculiarity to chicago that

means that plate glass in chicago is much cheaper than anywhere else in the united states. in the 1880's, a very large glass field was discovered in a central indiana and central ohio. plate glass is incredibly energy intensive. it uses a tremendous amount of coal, and by the 1880's, natural gas. this is why so much of the industry had been located around pittsburgh. well, when the trenton gas field was discovered in the 1880's, two industrialists who had been working in pittsburgh sort of did the math. they looked at the surveys of the gas field and picked the corners which were closest to the most robust real estate market in the country, which was in chicago. they realized that they located a factory in indiana, they would have a monopoly on chicago's glass. the other close plate glass

plant was in crystal city, missouri, so about twice as far away. for about 10 years, the two largest plate glass firms in the world were located in kokomo just down the rail line in elwood, indiana. and these essentially produced plate glass exclusively for the chicago market. the opening coincided with a period of economic depression in the 1890's. they overproduced. they were a little optimistic of what the market would bear. for several years plate glass ended up in chicago being cheaper than brick. if you are trying to decrease the amount of brick in your facade, increase the amount of glass, what do you end up with russian mark -- with? you end up with a building very much like the reliance building, a steel frame on the inside that

takes all of the structural functions of the exterior and internalizes it into a a self-braced frame. draped with as minimal and as transparent a curtain wall as you can possibly get on the outside. and this of course is the reliance's great reputation, the first curtain wall building. the most glassy to date. there is a good functional reason for it. this contemporary post card from a tourist who knows that this building is almost all doctors offices. it was designed for suburban doctors to have a place to practice downtown. with electricity still expensive, daylight was paramount. this explains both from a functional point of view, but also a material and economically point of view, why the reliance would have these windows which are in some cases up to 6-8 feet square. again, a student project looking closely at this -- the reliance

is one of the first buildings to use moment connections. so convincing all of the -- condensing all of the lateral resistance of the cross bracing scheme into a single joint in which the column and the girder are both slightly oversized to achieve a really, really firm connection between one of the other using riveting. you can see that the exterior is mostly glass, with terra-cotta in between. there is a new material that comes into play called enamel ed terra-cotta. which has a glossy service that is supposed to be much easier to clean. this results in a building that projects this sanitary image perfect for the medical profession. but also, as you can see removes the structure from the outside, and gives a wind bracing structure that essentially gets out of the way

of the lovable space. -- lettable space. perhaps a more notable building is built in the same year. the fisher is also a framed bu ilding with a terra-cotta and glass curtain wall. it has the unique situation of striking a deal with its neighbor to the north that didn't require it to have a masonry firewall. the reliance, at the back, if i go back for a second, it has two brick curtain walls that separate it from its neighbors and give it some fire protection. the fisher did not need that for reasons that had to do with this negotiation. and therefore as inland architects said when the building opened this is the first tall building in human history to be built without any bricks whatsoever. not totally true, there are some bricks that hold up the span

drals. if you look at it today, this looks like it has plenty of walls. but what inland architect means is that it has no brick walls. this is the first tall structure we have looked at from egyptian times, from roman times, gothic, renaissance, enlightenment -- here we have the first buildings that gets rid of brick entirely right, as a structural material or as a cladding material. from the construction imagery, you can see there is a self braced steel frame. you can see right through it. there are no sheer walls, all of the wind bracing is taking up in these heavy connections between columns and girders. on the right, you can see the cladding, which is going on from the middle of the building up and down. they left the cladding off of the building so that trucks can move in and out. there are reports of people standing and gawking at this type of building, one that starts up and builds down. to us, this is normal. this is how a curtain wall gets

assembled on a self braced steel based frame. this is something definitively new. something that we recognize as contemporary skyscraper construction. a steel frame that takes all of the gravity load, the self brace d against lateral forces, and a light wall with no masonry in it that simply hung from the steel frame. if you have to argue for a building being the first skyscraper, this is my choice. the fact that it is in chicago instead of new york may be important, maybe not, but this is the first one that is definitively knew. -- new. we got rid of bricks. better daylighting, more efficient floors. we get rid of those pesky strike-prone bricklayers, what's not to like? who will not like these new formula? and the answer of course is bricklayers. and as much as what we have seen up to now reflects the national

trends, almost universal trend in material and engineering technology, what happens next is peculiar to chicago. it may surprise you that building regulations reflect not only what is good for the city but the economic interests of developers themselves. developers and well-connected unions. the bricklayers in chicago in 1890's are very well-connected. so connected, in fact, that even as these curtain wall buildings are being permitted, they get the alderman of chicago to pass a new set of requirements in the building code. that require all exterior walls right -- this is loaded terminology -- the fisher building gets rid of walls. here is a code element that requires exterior walls to be a minimum of 12 inches of brick.

-- 12 inches thick. it also requires any terra-cotta used for fireproofing to be a minimum of eight inches thick. well, how many of you have laid a brick before? how wide is a brick? eight inches by four inches. these dimensions are not coincidental. these are bricklayers and the brick industry fighting back, saying that if you're going to use these new buildings, you will not get the benefit out of them that you have for the past few years. there is a section that has less to do with the bricklayers and more to do with common sense the double span bay windows featured on the reliance in particular get restricted both in depth and with and in spacing. this makes some sense. you don't want fire jumping from one page when other.

whether eight inches of brick is better or worse than eight inches of terra-cotta is not tested. again it may shock you to find out the alderman are so enthralled to the bricklayers union, but this is the way chicago has always worked. you can see the code impact almost immediately. adler and sullivan design a building for the stock exchange, the first to be permitted under the new code. they try to play the game of the bay windows. cantilevered windows that bring in the light from the street. but they are forced to space them so widely apart that they have to come up with another way to bring daylight into the building in between. here you see some early examples of what would become to known as the chicago window. a piece of glass and iron ore would framing that expands as -- or wood framing that expands

as far as possible to fill the void of the column bay. it has a fixed, six foot by six foot panel that is fixed glass double windows on either side for ventilation. adler and sullivan play around with this and it becomes the formula for the classic chicago frame that among other things is the essential recipe for louis sullivan's buildings and now, target, where the glass actually seems to sort of push against the limits of the still -- steel structure, the cast iron structure, in some parts behind it. whatever the code requires, the formula, sullivan is one of these people that masters what was the definition of true style. taking and ideal and making it manifest and being rigorous about it. this is the steel structure, the last skin, confined in this case

somewhat by the chicago code but raised to an art form. after just a few years of being mandated by the chicago code -- and these are the buildings that people look at as the true chicago style. right? the fact that it is in part informed by this work in the -- this quirk in the code goes largely unmentioned. it is a style, a way of building that makes sense and it is easy to express and makes itself invisible in the facade. there are a couple of things that happened that changed that very strong stylistic impulse. one of them was the plateglass gradually creeps up in price. world war i in particular, glass becomes an expensive commodity again. the indiana gas fields that have s fueled the glass industry is a completely exhausted by the turn of the century. the glass industry literally

used up the natural gas in the state and the glass industry moves elsewhere. so chicago no longer has its own sort of custom source of plate glass. and the other thing that happens is another, better way to illuminate buildings comes online. if you think about the structures that we have looked at, all of them rely on gigantic windows which is single glazed. 50 years before we have insulated glass. chicago gets hot in the summer cold in the winter. ' windows may be a desk and single glazed windows may be a great way -- and single glazed windows may be a great way to illuminate interiors, but they are a bad way to insulate. throughout the buildings you get reports of bookkeepers working with gloves on their hands. the chicago public library was too hot in the summer to sit and read. environment problems argue

against the large windows as a way to illuminate the interiors. at the same time, chicago around the turn-of-the-century, it begins to form a monopoly. they start to undercut their competitors and offer reduced wiring and fixtures if you sign up with them. they cut their prices and by 1910, electricity is as cheap in chicago as it is basically ever going to get. about the same time the advances in manufacturing electric light bulbs in particular take place that make the fixtures themselves economical. throughout the 1880's and 1890's, most of the buildings are wired for electric lighting, but electric lighting only used at night. the reason is that carbon filament lightbulbs last about 4-5 weeks and they have to be changed.

you want to be parsimonious about how you use them. you don't want to leave it burning all day, only bring them when you need to. it extends the lives of the difficult to replace bulbs. on 1910, the tungsten filament is perfected and it leads to bulbs with lives of up to 10,000 hours and it is not such a big deal to turn the lights on even during the daytime. you would certainly use them at night, but the efficient bulbs give off more light combined with the cheap electricity that suddenly is available in chicago, to provide a viable alternative for interior illumination. if you do not have to have big, heat conducting windows you wouldn't want to have them. therefore we start to see changes in the building skins of the skyscraper right around 1910. suddenly we start to see buildings where the windows are no longer as large as they

possibly can be, but they are small as they can be and still provide views out. they become less about the quantity of daylight coming in and more about the quality of what you see outside. here are two buildings around that era. you can see that in both -- well, in the case of people's gas, the construction remains the same. it is a narrow steel framed building. these are never proportions of columns. it has a very thin curtain wall skin on the exterior. that curtainwall skin is no longer made of terra-cotta and glass, it is made of terra-cotta and stone and glass. and instead of trying to make the windows as large as possible, the curtain wall in this case is about making the skin as insulating as possible. and making the windows as kind of comfortable as you can.

a place to view out, not necessarily a place to put light on your desk. you can see the same principle at work in the insurance exchange of 1911. both buildings interestingly still have light courts, which seems counterintuitive. if you can illuminate the interiors with electricity, why have all of that perimeter, why would you scoop out all that rentable area? and the answer is that this is -- these are buildings that are post electric lighting, but pre-air-conditioning. in the summer, these office buildings, the way they are ventilated, it was to open the windows, transoms above the doors and core doors and let cross ventilation flow from the exterior to the light court. so the light court you see here, the light courts that are in the insurance exchange, probably more better described as ventilation courts then light

courts. the other thing happens around this time which is rarely credited but has a huge change in the way that the buildings are constructed is the development of pneumatic tools. all of the buildings we looked at so far are essentially handmade. the riveted joints are created by physically hammering red hot rivets into these holes in those of steel beams. around 1910, the other technology that comes online is pneumatic power. a compressor that you can put on the ground and you can power with an internal combustion engine. air hoses that can be strung throughout the job site and can be brought to relatively small handheld tools that now have greater power than a human that swung it hammer -- human swung hammer. greater power than a swan

-- so you see a much smaller labor force putting together these riveted connections. these connections are more reliable and they go together more quickly. what this means is the frames are more efficient, they are faster to put together, and you see almost immediately a rise in building height once again. does it pain me a little bit that this is obviously a shot of a skyscraper going up in new york, yes it is. by 1914, chicago is still working under a relatively outdated code that has a strict height limit at about 260 feet on buildings. new york is more progressive, in 1914 they allow the woolworth building to rise to more than 700 feet using pneumatic riveted frames. you can see from the thickness it relies on moment connections throughout. as you can see a relatively quick construction process. this is just a few months worth of work on the right.

and a height that beat every height record in the world for an occupied building. it certainly beat chicago which was still laboring along with the 260 foot height limit. the other thing that makes these buildings possible is a similar revolution in elevator technology. the traction elevator and the electrically controlled elevator come around in the early 1900s. they allow faster speeds for elevator cabs. they can reach higher floors more quickly. and they allow electric programming, so that you begin to embody intelligence in how elevators pick people up. this is also roughly the time that we see the pushbutton elevators. elevators until this point, they are operated by people who are literally in the cabs driving them, all day. right around 1914 11915, you

get the first reports of elevators at night, not during the day, but at night that allow the occupants to push buttons. there is controversy on whether this allows more accidents or not. but it becomes a regular technology. this height would not be possible without the structural advances of riveted frames or the parallel advances in the electrically controlled and operated traction elevators. chicago i think in part stung by the success of the woolworth building, begins to sort of backtrack and the influence of the developers on the city is profound. the code is quickly scrapped in 1922, after the economic slowdown of world war i, and you begin to see buildings that take advantage of a loophole in the original code that allowed spires to rise beyond this 260 foot limit. the spires were meant for

churches, but here is doma magnate g -- gum magnate wrigley saying that this is a spire as well. the new code allows greater height, first of all based on a pyramid massing. past that hundred 60 -- cool hundred and 60 -- 260 foot line, you strike diagonals from the building edges and he can build in that envelope. this is the strauss building. the first building to put occupied space in that new area in the code. by the 1930's, architects and engineers are exploiting the code to make buildings well and -- and access best in excess -- in excess of 400 feet. this is the board of trade, they have a massing within the prescribed ability limit. also, as you can see, the board of trade is h shaped. they turned the light court in its inside out. everybody has an exterior view and every piece of the building

has -- is thin enough to allow cross ventilation. the light court proves not to be the greatest shape for ventilation, but by turning it inside out you can cross ventilate the entire structure. so chicago's code response to the needs of developers, but it also responds directly to the available technology. right? developers push the technology by their desire for greater height, more floors. engineers, architects, manufactures respond and what you see is this final burst of height. once the lid gets taken off by the city, these buildings that are 45, even 50 stories, by the 1930's. the story sort of ends around 1944. the depression that takes hold in 1929, comes in the midst of the greatest building boom the city has ever seen. there is a run on.

there are a few projects that are finished up during the early depression. some in the 1930's, the field building and merchandise mart. they are taking advantage of the cheap labor and very low materialistic prices. -- material prices to build buildings that developers hope will pay off when things up. you can see that by world war ii everything stops. construction in chicago comes to a complete halt and it will almost be 20 years before there is another skyscraper in the loop. that is a convenient cut off point to talk about the history of skyscrapers in the city, but it also makes it a pretty coherent group of buildings that historians have always looked back on, sort of wondering, what happened here? there is a sort of traditional story that got told in the 1950's that looks at these buildings really as the father figures for international style modernism in the 1920's.

this is a page spread from siegfried's book "space, time, and architecture" where you see the reliance building on the left juxtaposed with this project for an all glass skyscraper in germany, on the right. gideon's argument here is that burned him -- burnham was prescient, that he was striving for something, this modernist ideal of a glass box. i think it is more accurate to say that the reliance was a number of innovations that this generation looked back on as a proof of concept. that there were precedents for technical advances that married glass and steel. in this case, marion glass -- marrying glass and concrete. when we talk about concrete, it

and talk about glass, there are factors in 1921 that made this impossible to build. not least of which we have seen would be the environmental impact, that single glaze glass. rather than trying to tell this grand narrative, this art historical story about 20th-century modernism and how the 19th century chicago led into it, i would argue that actually what we might better do is look at chicago's skyscrapers as a barometer of american history, technical history construction history, at that moment. to understand that a later generation would look back on these buildings and be inspired. but to think of the buildings not as just the kind of introduction to another era, but as important in themselves. there's a sense that we can look at this family of buildings as "the tribune" dudeid and say that

they are good expressions of what the laws of nature, what we might call more material high polities or material truths, at least material influences. how smart people look at what is available in terms of technique, in terms of materials, and understand how those might get applied to complicated problems. i think also there is a sense that we can look at adler, to close out with him. adler wrote of being an architect in chicago at this time, the architect is not only an artist or engineer, but a man of science and of affairs. in other words, all of these buildings are all embedded in the economics, the industry, the labor, politics, in the technology, etc. of the day. they respond very, very quickly to technological change. they respond, as we have seen, very very quickly to political change. to industrial change. all of these talk about

buildings, architecture, sure, but buildings in a larger sense as being directly connected to all of these influences. as a result, when we look at the history of these buildings in chicago, or of course the point of the course, when we look at any large building at any moment, what we see is a snapshot of all of these influences around and rather than trying to read a future generation in these buildings, we can also read that time, that moment, and find out about what the city was like and the country was like around it. what the economy was like, the politics labor relations, etc. buildings are more than style, these buildings in chicago are examples of what designers and builders can do by engaging the really, really difficult often messy negotiations between what we want to do, functions, and the resources we have to

make that happen. thank you very much. [applause] >> we have time for questions. >> the construction after war -- world war ii, was it the arrival of the man who inspired the buildings after that? >> good question. the question is that the revival that happened after world war ii, was it inspired by his arrival in chicago. it is interesting. you will probably get different answers from different historians. he arrived and the cultural impact is huge. he designed his first buildings in the early 1940's, partly as a result from the funding he got from the government. trying to research materials for

the war effort. it was the economy that waits to pick up until after world war ii. world war ii ends in 1945 it was the early 1950's until there was a significant skyscraper downtown, the prudential building. and that was not designed by him. his skyscrapers come later and they come secondhand, through s l m, the firm that showed his influence. most importantly, as we will see later, he is profoundly influential on the ways that chicago buildings get built. but there has to be economics and that desire on the part of developers to build. and he had to wait like everyone else for that to happen. >> for those first material explorations as buildings start to get higher, you talked about how the building code had cap it

ped it later. how did the building code respond to the early ones? at what point did they say, no that is too tall? how did the building code respond to the initial prizes? -- initial rises? >> the question is how did the chicago building code respond to the initial efforts to build tall? if you look you can -- and there were no buildings -- building heights in the 1870's, or before the fire. there was no need to. nobody wanted to go higher than 5-6 stories. the first time you start to see building heights discussed during the aftermath of the 1874 fire, is when the city realized part of the reason buildings are dangerous is that if you build high, you have to run lower to get out. and firefighters of course need to access upper floors. so there are moments where the building codes offer different heights and there is a negotiation between three

parties, really. the city who is concerned about fire safety, developers that are not unconcerned about fire safety but are also concerned with making money, and interestingly, maybe the most influential, but it was building owners who were out of the loop. there is no blowhard but -- there is no to go hide but -- there is no urge to go hide but they all realized that if the height of the loop is cap then the real estate market if it can't go up, it will spread out. the discussion is really about fire safety, but it is also about this turf battle between downtown owners and surrounding owners. the building height, you can see long. here where it is capped at maybe 160 feet and it bounces back up to 260 feet when it is realized that 260 feet doesn't let you get 17 stories, it changes to 265 feet.

and then finally when architects begin taking advantage of this loophole that allows spires and towers. evidently that pressure makes things crumble. there are better fire proofing systems, better elevators, also better fire escape systems. by this point. and the city as you can see finally after the 20's backs way off and allows those tall buildings provided they get smaller as go up. >> chicago in its place in the 19th century obviously had, with the fire, it had effects on individual components in buildings. from your knowledge, do you have -- do you know syndicate changes -- significant changes in urban planning, where materials are placed in cities to combat things like fire? >> great question. the question is, what affects -- affects -- effects did the

fire have on urban planning code, in addition to individual components of the buildings? one thing that becomes apparent, not so much after 1871 when the rush to build tramples any effort to put a working building code in place, but in another -- but after 1874 which is a very near miss. the city loses 16 blocks but they do not lose the whole city. what happens is, there is a code that outlaws something called lightweight construction. so where there is real density light timber framing which is particularly flammable gets outlawed. heavy timber framing actually proves to be pretty resilient in a fire. click -- thick, heavy timbers

char on the exterior, they do not burn through. it represents a good way to build against fire. there is a code provision for slow burning construction. that is allowed in chicago, but not allowed downtown. as you can imagine, slow burning construction is not something that people get enthusiastic about. if you are building a new building or moving into a new building, you would much rather have a fireproof then slow burning. but it affects where you can build and what type of construction. light temper construction is banned to the suburbs. where, of course, it takes off. bungalow construction happens in the suburbs, but no longer downtown after 1874. >> what about the idea of the loop? and the concentric city? >> did the code have an effect on at the loop or what is considered the downtown. i do not think the code necessarily did.

in chicago, it was the psychology of being on one side of the river or the other. if there had been a demarcation drawn, that might have helped to define what the downtown area is. but with such a strong geographical definition of the rivers and to the south the rail lines, the loop has always been the loop. that has always been in downtown and is -- the codes very often call out that 49 blocks as where you can build to one height, or another, or in one material or another. chicken and the egg. the sense of the loop determines the code more than the other way around.

ok well, we will see you in a week's time when we will talk about the material that replaces iron and steel in the construction palette in particular in the united states -- concrete. a material that is fireproof and it takes place -- takes off in other places other than the steel capital. ok, we will see you then. [captions copyright national cable satellite corp. 2014] [captioning performed by the national captioning institute, which is responsible for its caption content and accuracy. visit ncicap.org] >> monday night at 10:00 p.m. eastern, and nbc news special report. "communist saigon" from 1975.

it details events in the weeks following the end of the vietnam war. and nbc news of a report from 19 74, "communist saigon." >> my name is dr. malcolm beach and i am president of the living history association and i am from north carolina. today we are having a reenactment called the grand review parade. this, in fact, is a reenactment of the victory parade held at the end of the civil war 50 -- 150 years ago. down pennsylvania avenue. however, in that particular parade, the united states colored troops were not allowed to march in this victory parade. so what we are doing today is we are correcting that oversight. end of the-- and the uscts will

march in victory today down pennsylvania avenue. officers are going to march today. >> i am from a small town about 20-25 miles east of memphis. well, today i am here honoring my great great grandfather. he was from tennessee, macon tennessee. he enlisted in the u.s. colored troops regiment in 1863. so i will be walking down pennsylvania avenue for my great-grandfather. it will be a great adventure. [drumming] >> free at last! >> 1, 2! >> it is a matter of historical fact that president lincoln issued the emancipation proclamation.

as a matter of military strategy. prior to that, the south was winning most of the battles. with the emancipation proclamation, it allowed african american forces to fight with the armed forces of the union. over 2000 of them joined with the navy, the infantry, and the cavalry. you have fresh recruits coming in in 1853. after 1863, the north begin to win more battles. we think the colored troops had a major role in the overall union victory. [trumpets] [battle hymn of the republic playing]

>> ♪ glory glory, hallelujah glory, glory hallelujah glory, glory, hallelujah his truth is marching on ♪ [drumming] [trumpets] >> ♪ his truth is marching on ♪ [applause]