directory is a handy guide to the 114th congress, with color photos but every senator and house number plus bio and contact information, and twitter handles. plus, a foldout map of capitol hill, a look at congressional committees, the president's cabinet, local and state governments. order your copy today -- it is 13, 90 five dollars -- it is $13.95 on c-span.org. >> american history tv sits in on a lecture with one of the nation's college professors. you can join in every time it 8:00 and 9:00 eastern. iowa state professor thomas leslie talks about the changes in 19th-century architecture design and technology. new materials and foundation methods allowed buildings to be built to learn and incorporate more classic to let -- more

glass to let in more like an 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 still amount -- 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 shrill around its meet of masonry that may be self-supporting.

-- with a shell around it made of mtetal masonry. we won't see how that is developed in a particular place in a particularly robust way. this intersects with a robust economic progress in a location that is fairly new for us in this course -- that is the united states, the americas. american history at this point was one of westford 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 state where the first skyscraper is, chicago partisans will tell you that of course 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. almost anyone can tell you that chicago architecture, there skyscrapers in particular, related to this one quote from louis sullivan -- form follows function. we take this is one of our starting points and talk about the way that this doesn't get the whole picture, buildings are not only about function and performance. we look at louis sullivan's business partner until 1895, and his reaction to sullivan's quote. he pointed out that if it was as simple as form follows m

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 looked very different from the sears tower, or from the burj khalifa. even though their functions are the same and 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, he thinks about the available materials and techniques that one has to build with. 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 the piling floors on top of one another and the available material, relatively

simple brick. the skyscraper built in the late 19th century, when there is iron and glass, when there are elevators in particular, will look very different. in chicago's, we will see a particularly 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 tall commercial buildings in britain, we will look at bill construction in particular. --- mill construction. 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 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 are limited by the number of stairs people were willing to climb. it was less so in mill construction, where you sound worried about your worker's comfort. but when you print out a space you need that accessible easily. -- rent out a space. 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 elimination. these buildings up to the 1880's are mostly illuminated by daylight or bite eliminating -- or by iolluminating 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 not illuminated by daylight is in his words "non 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. you will see examples of what this means to planning and layout in a minute. the skyscraper is a new building type that relies on advances that have gone on in the early 19th century. 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 changes and impacts the

need to eliminate spaces by sunlight. -- illuminate spaces by sunlight. these mills that used cast iron beams whose shape follows the ideal shape, the ideal loading diagram of a structural member in bending. this is only possible in cast-iron, in wrought iron 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 remains 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 built in the 1870's and 1880's that 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 a 5-7 stories in manhattan. as you can see from the construction photo they are essentially cast-iron construction wrapped in a mastery jacket -- masonry jacket. the trading floor from the potus exchange, -- produce exchange, this has cast-iron beams which are then closed with a near classical dress. what is essentially happening is similar construction to that of the british mills cast-iron columns, rot iron beams, and masonry walls used to handle the lateral bracing.

with these proto-skyscrapers with mill construction already there, with most of the construction needed to build tall buildings, what happens to shaw cargo 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 drive or 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 end of making more money by piling floors on

one another and particularly making those forced 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 adventures -- technical advances in elevators that had cast-iron facades. there is a reason of that chicago becomes a world center for fireproof innovation in the 1870's. at that happens see that these masonry walls that surround these mills and proto-skyscrapers begin to become skeletalized. they begin to morph from walls into piers, morphing the outside to bring more daylight in. perhaps the greatest confirmation occurs in the late 1890's, when it still replaces wrought iron as -- 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 the building are no longer charged with supporting the structure against either wind or gravity and how does that free the exterior to bring in even more daylight? there are a couple of peculiar things that happen in chicago in the 1890's that influenced the way that skyscrapers develop. we look at those. and finally, we will talk about influence and how the model of those chicago skyscrapers influence technically inclined architecture in the 20th century. we'll start with the city itself. in particular, chicago's geography and how this impacted buildings in the loop and how the way people thought about buildings in particular. to do this, i will rely on an art with put forth by william

cowan in a 1992 book, "dangerous metropolis" that argued that chicago's importance had to do with the midwest position it existed in. chicago was founded in part because it existed near the sport near the end of the chicago river -- 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. i disestablished chicago as a streaking post. -- this established chicago at the trading post in 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 had even more to do

with this growth. if you are trying to get produce for iowa, for example, to new york, you have to go around the southern end of lake michigan. railroads from the west and 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 can sell to a market out east. you can make money in chicago based on what people are growing and i what, or what people are buying in new york. they were a sort of middle. -- middle man. as conan points out, the economic sphere includes the entire midwest. in iowa, you may have thought of yourself as a far western suburb of chicago.

most of what happened here economically had some thing to do with trading or banking or financing in the city. that huge area of land both profited from an controlled 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. the chicago river was just east of michigan, it has not 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 supportively, for our story, -- most importantly, this relatively cheap construction that first gave offices for bankers, traders speculators and later became a commodity itself. real estate was in office buildings that could be bought and traded just like coin 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 on the street as large as possible. therefore, to make the office spaces inside as attractive as possible and as lettable as possible. even through the routine 1870's and 1880's, chicago commercial real estate with generally 5-8 stories. nothing about that. in part because elevators are

still slow, but mostly because there are still structural problems with cast iron and timber framing. elevators in particular allowed offices on the fifth or sixth for it to be justifiable as offices on the first floor. -- just as valuable as offices on the first floor. in 1853, this is document it by a nestorian -- a historian --it 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 assistant is coming to court 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 unr uffled. this was a major advance. elevator disasters were fairly common, and they were used almost entirely for freight through the 1850's. otis'invention of this safety device makes it commercially viable. we see the first use for people in attendance in the 1850's. 00-- for tenants in the 1850's. this takes place in the crystal palace, built in 1854, the immediate area of the london crystal palace that we discussed earlier. chicago also imports cast iron from a new york. there are cast-iron facades that are built throughout the loop in the 1850's. there are advances from the post-fire area, including the berg off 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 how britain gives -- how bricks works as a facade material versus the advantages of cast-iron which is much stronger and lets you accomplish the same 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 and a daylight that you get. this will become a constant theme, replacing the heavy break 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, proved that this is completely untrue -- that cast iron is in fact entirely vulnerable to fire. in this image of the aftermath

of the 1871 fire, that the remains of cast-iron buildings are scattered throughout the loop. what happened here are two things -- firstly, the contents of the buildings themselves have burned. the cast iron hasn't ignited but certainly weakened and assaulted 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 a cast-iron buildings the sudden quenching of the red-hot cast-iron wood called the structural members to shatter, bringing down the building around. -- would cause the structural members to shatter. it destroys another 16 blocks of chicago. there is a real effort in the city to try and reforming 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 vanishing, -- for foundation, but fantastic if you are a brick maker. they start springing up as early as 1830. by the 1850's, brick as a technology has moved well beyond its medieval or ancient origins. we have a number of machines that not only make brick work quick 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 looked at the beginning as a brick as a building material, in egyptian and roman times.

we saw that there was a big distention between brick that was just mud drickbrick, with a compressive strength of 3500 180 kg /cm. pressed brick adds an order of magnitude to the strength of the material. with hydraulic pressing and a lengthy kiln firing, we have doubled or cost to build the strength of brick yet again. the machines that come online in 1860's allow us to achieve the same structural path 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 you find that there is a generation of buildings fairly early on that expresses the arrival of these break

pressing machines into the city. skyscraper height jumped noticeably on average you stories at a time. -- 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 attend stories right? -- than 10 stories right? it would not even be the tallest building on his block today. on montauk used cast iron and a wrought iron on its exteriors and floors. 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 -- if you are trying to open up large windows on the exterior, brick is heavy. it is not 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 or retail, the self weight of the brick demand larger and larger piers. the floors that have the most brick, the least glass of the once 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 cracking or swaying in the wind. 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 bricklayers have a particular reputation of being strkike-prone.

they had these unrealistic demands like getting half a day off on saturday from working. [laughter] they tended to be reluctant to employ brick than usual. 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 take these walls and distill them to what we make think as piers. the same clay that the city builds itself out of is the worst soil to build a heavy skyscraper on. you see solutions to the problems of the foundations in the late 1880's. architecture engineers realized that to cope with the original settlement it is easier if you calculate foundations, if instead of bringing law foundations down to the ground, -- 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, heavy -- big heavy space pyramids. these are essentially slabs in reverse that take loads from individual column or pier and spread them out over soil below. we will see solution like friction pierse, where you are relying on the grip of this weyt 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 foundation to the weight skyscrapers are -- to the way skyscrapers are built above ground, is that this gets architects to think of structure not as walls, but as columns.

you are more likely to think of the structure above as a great instead of as a series of walls/ -- as a grid. 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 walls that have frustrated efforts int the montauk and turn those piers 90 degrees to the street. the brick here in the jewelers building reads more like a pier. these piers are 3-4 feet deep that go into the building to get the area needed to carry the load. you can see they allow very large windows. you are also getting to see these height brick 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. we have brick piers that respond to this before daylight and foundation. 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 as 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 airspace that takes 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, these are layered steel columns but the cte rra-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 dow was the structure with water. -- and douse the structure with water. this is from the "fireproof structure" from about 10 years ago. these all rely on it 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. the iron frame developing as a response to both concerns about structure, concerns about fireproofing, and concerns about adaylighting.

a well-known engineer from the time begins to develop this in a warehouse building, called the first later story. -- 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 held in their structural task by these iron columns behind them. they can be smaller and as a result the windows can be larger. you can see this upstanding from the four is very low. -- fromt he 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. he says 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 move it along one step. he has invented 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 one of 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 as we think of reinforced concrete today. you can see the blue is all caps oast iron, the blue isgreen 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. without an adequate lateral bracing system, the building will rack, 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 edge of the lot, he still has masonry sheer walls that are doing a lot of the work of resisting wind blows. this detailed the cast-iron columns embedded in masonry is also capable of bcarrying

a certain amount of wind load. that will assist the building in standing up against any lateral forces. very much a hybrid structure. mediates proto-skeleton frame but relying on it 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 across the street. this is still there, and actually can store. -- immaculately restored. it used iron and break in the structure. there is an exterior skin of all masonry. then and your 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. this is potentially valuable real estate in the middle of the rookery that has been 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. the jacket of iron in a way that has a much different feel than on the exterior, . also critical is that exterior skin of the masonry is the rookery's primary wind bracing. if the wind blows from left to right, there is enough stability to keep it stable. we have seen the masonry used as sheer walls to keep the building operator against wind.

the exterior of the building is still largely brick. because we need that much break to resist the wind load, we are still restricted in the amount of glass we can have. we would like to get more daylight into those exterior offices in particular. one step towards what we would call the modern skeleton structure and hung curtain wall happens in 1899. a man 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 wind bracing with a structure that is totally internal. you can see that the tacoma still relies on cast-iron columns and it has four massive sheer walls one going

north-west, one going east-south. they are particular to the street walls. they create a very lightweight the near of last -- veneer of glass and terra-cotta that hung from the outside. 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 another student project looking at the anatomy of the tacoma's skeleton. you can see there is cast-iron in a light green, wrought iron in a dark green. you can see the terra-cotta fireproofing along the joist beams. then you see this terra-cotta skin on the outside. that contrast would be massive sheer walls said 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. the tribune 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 with this glass on the facade, with much structure hidden. if we look at the plan of the tacoma the brick is still taking up a tremendous amount of space. it reduces the amount of flexibility we have in offices. more importantly, it is can't be rented out. you cannot rent out a recall, you can only rent out open for space. -- you cannot rent out a brick wall. they also wants 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. that is her 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 about the processes involved in making these two. cast iron is taking raw pig iron melting it and pouring it into a mold. it has a very high carbon content, relatively, which gives it great compressive strength and making it also 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 workable. 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 a refining process in the 1880's, later called the open hearth process, alleged to refine the amount of carbon you are producing. you are trying 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 the balance between compressive strength and tensile strength. lets you make very efficient beams. but it also gives you ductility nearly the strength of cast-iron with the workability of wrought iron. this makes it a brilliant material if you are trying to make very precise connection. bridge design in the 1880's

starts looking at how we can exp and the stand, which rely on translation and fixed joints. these wind bracing 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 can come back and -- can't come back and drill precisely. you can't mold it after it is cool. you have to cast molds where you want them to be. when cast iron cools, it shrinks on predictably. it twists, and those booltlt holes never get where you want them. sot he bolt holes need to be oversized, so that you can get it in somewhere. that means that the connections are always lose. if you try to build a wind brace

structure out of iron, you find that it is rickety. eventually the connections loosen and the structure collapses. this was what happened in a bridge disaster in scotland, it makes engineers nervous about using cast-iron in any structure that is asked to take on the load of the wind. steel's great contribution to the chicago skyscraper and friends 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 to get a precise whole and then used a hot rivet to attach those two pieces of steel,. which as it cools draws the pieces together more tightly. if you look at related connections with steel, like

you're on the right, or these examples of ways of achieving wind bracigng 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 friends to be self braced against wind and eliminate need for masonry in a tall building auction. construction. chicago is located in between a coalfield and southern italy ndiana. iron comes from minnesota by both. chicago becomes the center of the steel industry in north america, along with pittsburgh.

if you chart tghehe heights of chicago buildings, you see this whole generation of structures that leavesps up in 1890 after the refining process. leaps up because of legacy building codes. it leaps up between 15-20 stories for a good henumber of years. this is the old colony building on south dearborn. it uses a technique called a portal frame. it literally makes a monolithic connection between the steel columns are and the steel girders there. can see on the plan at the left that this replaces very thick sheer walls with skinny steel elements. you can also see that these elements can be 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 realm road bridge -- 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 before plan. -- 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.

if we have solved the problem the self-raised rframe, iron can handle loads better than brick, steel can handle lateral loads much more efficiently than brick. we took the structural function away from the exterior skin of the building. what does this mean for our elevations? remember that the critical thing about building facades in the era is bringing in as much daylight as we can. we can imagine there will be a push to take advantage of all of this newfound space on the building exteriors. in fact, this is what we see. even in buildings that have a relatively conservative wind bracing, like the pontiac of 1891. this is 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. east-west ion site. that sheer wall takes all of the wind load in one direction and the multiple number of columns into the other direction handles 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 creating windows made of brick and terra-cotta, so still relatively heavy to our eyes, but offering amount of huge window glass and their late to the interior. -- 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. that is certainly true.

it presents some of the inherent problems in masonry construction. if you look closely, you can see 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 and, you take a s eparate step 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 bracing against wind laterally. if you look only at the masonry doing the actual structural work, what you find is that is monolithic skin skin options in two ways. some of the masonry is doing the work of holding the building up,s 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 a simply self-supporting brick. it is doing nothing structurally. all it is doing is maintaining the integrity of the exterior skin. john ruth, the designer, chose to detail the building which chose this monolithic brick mass. but as this student project shows, the brick is doing two things. there is some brick that is structural, some that is padding the floor. and veneered, as it was negatively called in the day. there wass a significant amount of steel in this building. the veneer gets challenged in the 1880's by 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

break 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 national trend. but there is a geographical peculiarity to chicago that means that plate gglass in chicago is much cheaper than anywhere else in the u.s. in the 1880's, a very large glass field was discovered in a central indiana and ohio. plate glass is incredibly energy intensive. it uses that in tremendous amount of coal, and by the 1880's, natural gas. this is why so much of the industry had been located around pittsburgh. wendy trent tengasco was discovered in the 1880's, two industrialists who had been working in thiss pittsburgh did the math.

they looked at the surveys of the gap field and looked 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 plant was in crystal city missouri, so about twice as far away. for about 10 years, the two largest plateglass firms in the world were located in kokomo, just down the rail line in elwood, indiana. this essentially policed plate -- produced plate glass exclusively for the chicago market. it coincided with the economic depression in the 1890's. they overproduced. they were a little more optimistic of what the market would bear. plate glass ended up being cheaper than brick.

if you are trying to increase the knot of -- the amount of glass, what do you and upendend up 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. this is the reliance's regurgitation, the first curtain wall building. -- reputation. there is a good functional reason for it. this contemporary ports card -- 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. the was expensive.

-- electricity was expensive. both from a functional point of view but also a material and economically to view, why the reliance would have these windows which are up to 6-8 feet square. again, a student project looking closely at this -- the reliance was one of the first buildings to use moment connections. 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 very firm connection between one of the other using riveting. you can see that the exterior is mostly glass, with terra-cotta in between. it is a new material that comes into play called enamel terra-cotta. it has a glossy service that is supposed to be much easier to clean. this results in a building that

rprojects this sanitary image, perfect for the medical profession. it removes the structure from the outside, and gives a wind bracing structure that gets out of the way of the lettable spo ace. 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 neighbors to the north that didn't require it to have a masonry firewall. the reliance, 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.

this is the first all building in human history to be built without any breaks whatsoever. -- any bricks whatsoever. not totally true, there are some bricks that hold up the struc ture. if you look at it today this looks like it has plenty of walls. but what he 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 as a structural material or a padding material. from the construction imagery you can see there is a self braced steel frame. there are no sheer walls all of the wind bracing is taking up in these heady connections between columns and girders. on the right, you can see the cladding which is going on from the middle of the building of

and down. the looped the cladding off of the building so that trucks can move in and out. people are 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 normal skill-based frame. -- steel based frame. this is something definitively knew. something that we recognize as contemporary skyscraper construction. a steel frame that takes all of the gravity load, the self brace against lateral forces, and a light wall with no masonry simply, 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. we got rid of bricks.

we get rid of those pesky striekke-prone bricklayers what's not to like? who will not like these new formula? and of course the answer is bricklayers. as much as what we have seen up to now reflects the national trend, and a most universal trend in material and engineering technology, what happens next is sillier to chicago. -- silliepeculiar to chicago. it reflects very closely the economic interests of developers themselves. developers were well-connected. 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. they require all exterior walls -- 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. it also requires any terra-cotta used for fire to be a minimum of eight inches thick. well, how many of you have laid a break before? how wide is a brick? eight inches by four inches. these dimensions are not quintessential. -- qcoincidental. these are bricklayers and the brick industry saying that if you're going to use these new buildings, you will not get the same benefits out of them. 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. your quantifier jumping from one bay to another, -- you don't want fire jumping from one page when other. weather eight inches of brick is better or worse than eight inches of terra-cotta is not tested. it may shock you to find out alderman or so enthralled to the bricklayers union but this is the way chicago has always worked. you can see the code impact almost immediately. amber and sullivan -- adler and sullivan designed the stock exchange, first to be permitted under the new code. they tried to play the game of the bay windows. bringing in a borrowed 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 a light 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 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, 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 pushes against the limits of the still structure, the cast iron structure, in some parts behind it. whatever the code requires, the formula, sullivan is one of

those people that masters what was the definition of true style. taking ideal and making it manifest and being rigorous about it. this is the steel structure, the glass skin confined 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. the fact that it is informed by this work 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 it -- makes itself invisible. 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, glass becomes an expensive commodity again. the indiana gas fields that have 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 custom source of plateglass. and the other thing, and other better way to eliminate buildings comes. 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. and single glazed windows are a quick -- great way to eliminate 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 eliminate the interiors. at the same time chicago around the turn-of-the-century, it begins to form a monopoly. edison undercuts competitors and offers reduced wiring. they cut their prices and by 1910, electricity is as cheap in chicago as it is going to get. about the same time the advances in manufacturing electric light bulbs in particular, take place that make the fixtures themselves economical.

drop the 1880's and 1890's, most of the buildings are wired for electric lighting, but it is only used at night. the reason is that carbon filament lightbulbs last about 4-5 weeks and then they are changed. you want to be parsimonious about how you use them. you don't want to leave it running all day, only bring them when you need to. it extends the lives of the difficult to replace faults. around 1910 this new 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 wouldn't 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 to interior illumination. if you do not need big he conducting windows you wouldn't

want to have them. you start to see changes in the building skins of the sky capers around -- skyscrapers around this time. you 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. they are less about the quality -- less about the quantity, but more about the quality of what you see outside. here are two buildings around that era. you can see it in both, in this first one, this is a moment -- a still frame building. these are never proportions of columns. it has a very thin curtain wall skin on the exterior. at curtainwall skin is no longer

made of terra-cotta and glass it is made of terra-cotta and stone and glass. instead of making 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 comfortable as you can. a place to view out, not a place to put light on your desk. you can see the same printable at work in the insurance exchange of 1911. both buildings interestingly still have liked courts, which seems counter intuitive if you can illuminate the interiors with electricity, why have all that parameter, why would you scoop out all that printable 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, transcends above the

doors and core doors and let cross ventilation flow from the exterior to the light court. the light court you see here, in the insurance exchange, probably more better described as ventilation courts. the other thing happens around this time which israeli credited, but it 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 our handmade. the riveted joints we sought to instill connections were 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 you can put on the ground and you can power with the internal combustion engine.

air hoses that can be strung throughout the job site and can be brought to relatively small handheld tools, now they have greater power than a swan hammer. 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 immediately a rise in building height once again. does it pay me that this is obviously a shot of a stack favor going up in new york, yes it is. by 1914, chicago is still working under a relatively outdated code with strict height limits, about 260 feet on buildings. new york is more progressive, in 1914 they allow the woolworth building to rise more than 170 feet using pneumatic riveted

frames. you can see from the thickness this relies on connections throughout. he can see a relatively quick construction process. this is just a few months worth of work on the right. and a height that be every height record in the world for an occupied building. it beat chicago which was still laboring along with the 250 foot height limit. the other thing that makes these buildings possible is similar revolution in elevator technology. the traction elevator and politically controlled elevator around in the early 1900s. they allow faster speeds for elevator cabs. he can reach higher floors more quickly. and they allow electric programming, so that you begin to embody intelligence and how elevators pick people up. this is also roughly the time that we see the pushbutton

elevators. until this point, they are operated by people who are literally in the cabs driving them, all day. around 1914, you get the first reports of elevators at night not during the day, but at night that allow the occupants to push buttons. this is -- there is controversy on whether this allows to more accidents or not. but it becomes a regular technology. this height would not be possible without 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 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 the 260 foot limit. the spires were meant for churches but 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 200 60 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 access 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 best for ventilation, but by turning it inside out you can cross mid-to-late the entire structure. chicago's code response to the needs of developers, but also responds directly to the available technology. developers push the technology by their desire for greater height, more floors. engineers and manufactures respond and what you see is this final burst of height. once the lid is taken off by the city, these buildings that are 45, even 50 stories, by the

1930's. these stories and around 1944. the depression that takes hold in 1929, comes in the midst of the biggest building boom. there is a run on. a few products that are finished 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. and the buildings are things that the builders hope will pay off. i will work to, everything stops. construction in chicago comes to a 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 sky craves -- a sky strippers in a city, but it also makes it

a pretty coherent group of buildings that historians look back on, sort of wondering, what happened here? there is a traditional story that got told in the 1950's that looks at these buildings as the father figures for international style modernism in the 1920's. this is from the book " space, time, and architecture" where you see this project for an all glass skyscraper in germany, on the right. the argument here is that burn him -- burnham 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. there was presidents for technical advances that married glass and steel. in this case, glass and concrete. when we talk about concrete, it thinks -- and talk about glass there are factors in 1921 that made this impossible to build. not least of which we have seen with the environmental impact, that single glaze glass. rather than tell this grand narrative or this 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 technical history, construction history, at that moment. to understand that a later generation would look back on these buildings and be inspired. to think of the buildings not as

introduction to another era, but as important in themselves. there's a sense that we can look at these buildings and say that they are good expressions of what the laws of nature, what we might call more material high polities or material truths these material influences. how smart people look at what is available in terms of technique materials, and understand how those might applied to consultative problems. i think also there is a sense that we can look at adler, to close out with him. he wrote that being an architect in chicago at this time, the architect is not only an artist or engineer, but a man of science and affairs. these buildings are all embedded

in the economics, the industry the labor, politics, in the technology, etc. of the day. they respond quickly to technological change. they respond quickly to political change. two industrial change. all of these talk about buildings, 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 the point of the course, looking at any large building at any moment, what we see is a snapshot of all of these influences around and rather than read future generations 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 in and around it. what the economy was like, the politics, laborer at -- labor

relations, etc.. buildings are more than style, these buildings in chicago are examples of what designers and builders can do by engaging messy negotiations between what we want to do, functions, and of the resources we have to make that happen. thank you very much. [applause] we have time for questions. >> the construction after war were to -- world war ii, was it -- who inspired the buildings after that? >> the revival that happened after world war ii, it was in spidered -- inspired by -- in chicago. it is interesting.

you will probably get different answers from different historians. the cultural impact is huge. -- designed his first buildings in the early 1940's, partly as a result from the funding he got from the government. the economy though weight to pick up until after world war ii. that was in 1945 it was the early 1950's until there was a significant skyscraper downtown the prudential building. and that wasn't designed by nice. his come later and they come secondhand through s l m, the firm that showed his influence. nice, as we will see later is profoundly influence of 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 they got higher, you talked about how the building code had cap it later. how did the building code respond to the early ones? at what point did they say, no that is too tall? >> 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. nobody wanted to go higher than 5-6 stories. the first time you start to see the building heights discussed after the fire, is when the city realized part of the reason

buildings are dangerous is because if you buy -- if you build high, you have to run lower to get out. and firefighters need to access upper floors. so there are moments where the building codes offer different heights and there is a negotiation between three parties, the city who is concerned about fire safety, developers that are not unconcerned but they are concerned with making money, and interestingly, maybe the most influential, but it was building owners who were out of the loop. 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 they take advantage of that loophole where they take advantage of spires. and that makes things crumble. there are better fire proofing systems, better elevators, also better fire escape systems. the city backs way off and allows those tall buildings to go up. >> chicago 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 in urban planning, to combat things like fire? >> the question is, what affects did the fire have on urban planning code, in addition to individual components of buildings? one thing that becomes apparent, not after 1871 when the rush to build tramples any effort to put a working building code in place, but in another fire, it is a near mess -- miss they do not lose the whole city. what happens is, there is a code that outlaws something called lightweight construction. where there is real density light timber framing which is

particularly flammable, that gets outlawed. heavy timber framing actually proves to be resilient and a fire. sick heavy timbers chart 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 allowed in chicago, but not allowed downtown. slow burning construction is not something that people get enthusiastic about. if you are building a new building or moving it in, you would much rather have fireproof van slow burning. but it affects where you can build and what type of construction. light temper construction is banned to the suburbs. and then bungalow construction happens in it the suburbs, but no longer downtown after 1874.

>> what about the idea of the loop? >> did the code have an effect on at the loop or what is considered.com? i don't think the code data. -- code did. in chicago, it was the psychology of teen on one side of the river rather than the other. you need john somewhere, where you could build light timber or not. that helped define downtown. with such a strong geographical definition of the rail lines and the river, 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 21 height, or another, or in one material or another. chicken and the egg. ok, we will see you in a week and we will talk about the material that replaces iron and steel in the construction palette in the u.s. -- concrete. it is fireproof, and it takes place -- takes off in other places other than the steel capital. we will see you then.