earth, looking at one side of australia. eastern australia. watching a shooting star come in between me and the earth. at first, i had the standard reaction of wishing upon a star. that i had the sobering realization that that was a huge, dumb rock going 20 miles a second that missed us. if it had hit us, it was big enough you could see it, we would have been debt in an instant. >> sunday night at 8:00 eastern and pacific on q&a. >> each week, american history tv sits in on a lecture with a college professor. even watch these classes at 8:00 and midnight eastern. next, 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 collar and -- built taller and incorporate more more glass to let in more light in 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 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 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 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 ir skyscrapers in particular relate 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 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 means environment in terms of the kind of context in which 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. a 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, we will see a particularly robust example of this negotiation between a function and this palliative ate of 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 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 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 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 illunination. 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 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 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 masonry jacket. the trading floor from the 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, 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 shaw 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 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 end of making more money by piling floors on one another, and particularly making those 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 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. as that happens, we'll 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 transformation 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 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 influenced 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 argument 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 n the midwest. 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 from a 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 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 from 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 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 were

growing in iowa, or what people are buying in new york. 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 profit 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 ave, it has not

changed a bit since then. you can see that is iowa's forest, 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, traders, speculators, and later became a commodity itself. real estate was in office buildings that could be bought and traded just like corn from iowa that could be bought and traded. 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 was 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 floor to be 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 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. otis's invention of this safety device makes it commercially viable. we see the first use for people and for tenants in the 1850's. this takes place in the crystal palace, built in 1854, the immediate era 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 couple 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 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 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 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 a cast-iron buildings the sudden quenching of the cast-iron caused the structural members to shatter, bringing down the building around. 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 foundations, but fantastic if you are a brick maker. they start springing up as early as 1830. by the 1860'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 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 looked from the beginning as a brick as a building material in egyptian and roman times. we saw that there was a big distinction between brick that was just mud brick, 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 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 skyscrapers 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 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 his block today. the 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 demands 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 racking, 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

strike-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 1880's.

architects and 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 begins with solutions in stone around 1882. around then, surplus rail iron is used to replace these, take -- we will see solution like friction pierse, 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 foundation 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 id. 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 had frustrated efforts in 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 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 need for 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 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 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 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 daylighting. a well-known engineer from the time begins to develop this in a warehouse building, called the first 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 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 jenny'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 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 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 cast iron, 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. without an adequate lateral bracing system, the building will rack, doors will not open and over time 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 detail of the cast-iron columns embedded in masonry is also capable of carrying a certain amount of wind load. that will assist the building in standing up against any lateral forces. very much a hybrid structure. a 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 immaculately restored. it used iron and brick in the structure. there is an exterior skin of all masonry.

an 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. to 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

brick to keep it stable. we have seen the masonry used as sheer walls to keep the building up 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 1889. 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, two going north-west, two going east-south. they are perpendicular to the street walls. they create a very lightweight 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 light green, wrought iron in 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 set at 90 degrees from the street front that keeps the building of against wind storms. even though it seems advanced, at the time it 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 buildings 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 space that can't be rented out. you cannot rent out a brick

wall. 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. 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 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 makes 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 allow you 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 expand the span, 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't come back and drill precisely. you can't cut it after it is cool. you have to cast holes 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 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 d 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 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 to get a precise hole 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 iveted connections with steel, like 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. chicago is located in between a coalfield and southern indiana.

iron comes from minnesota by boat. chicago becomes the center of the steel industry in north america, along with pittsburgh. if you chart the heights of chicago buildings, you see this whole generation of structures that leaps up in 1890 after the refining process. because of legacy building codes. between 15-20 stories for a good number 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 here 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 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 -- steel 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 convenient 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 frame, 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 tacoma. you can see there is a similar approach to wind bracing in up-down on the screen. east-west on site. that sheer wall takes all of the wind load in one direction and the multiple number of columns in 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 window glass 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 sorts of problems too in terms of foundation. if you walk into the building from the north end, you take a 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 brace 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, 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 makes us read it as a 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. veneered, as it was negatively called in the day. there was 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 if we're trying 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 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 u.s. in the 1880's, a very large gas field was discovered in a central indiana and ohio. plate glass is incredibly energy intensive. it uses that 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.

when teh field was discovered in the 1880's, two industrialists who had been working is pittsburgh did the math. they looked at the surveys of the gas field and looked to the most robust real estate market in the country, which was in chicago. they realized that if 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. these essentially 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 amount of glass, what do you end 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 reputation. the first curtain wall building. 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. 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 projects 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 space. perhaps a more notable building is built in the same year. the fisher is also a framed building 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 bricks whatsoever. not totally true, there are some bricks. 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 cladding 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 up and down. they left 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 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 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. we got rid of bricks. we get rid of those pesky strike-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 almost universal trend in material and engineering technology, what happens next is peculiar 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 fireproofing 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 coincidental. these are bricklayers and the brick industry saying that if you're going to use these new

technologies, 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 wieth 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. it may shock you to find out alderman are so enthralled to the bricklayers union, but this is the way chicago has always worked. you can see the code's impact almost immediately. 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 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 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 then a double hung windows on either side for ventilation. [captioning performed by the national captioning institute, which is responsible for its caption content and accuracy. visit ncicap.org] [captions copyright national cable satellite corp. 2015]