Mechanical Systems

A Difference Between Structural and Systems Technology

by Don Friedman on February 19, 2019


That’s a picture I took in a church attic some time ago. The wood members in deep shadow are the purlins and plank deck of the roof, and are fairly ordinary structure for a building constructed circa 1900. The brightly-lit piece of wood is a support for the electric wiring, and the wiring is of course the point of the photo.

The wiring is a great example of the knob and tube system. Bare or almost-bare wires were strung taut through void spaces (for example within stud walls, or within the joist space of floors), supported mostly by porcelain spools. The stubby white cylinders in the photo are those spools. There were different types of spool: sometimes the conducting wires wrapped around the spools, sometimes (as here) they passed through a hole in the spool. The tubes were porcelain tubes put into holes drilled though studs or joists to keep the wire separate from the wood as it passed through. In this particular case, it looks like might be remnants of some wrapping on the wires, but they’re generally bare.

Note also, the large number of parallel wires. Each goes to a different light fixture in the ceiling of the sanctuary (the ceiling was the floor of the attic space I was standing in). Early bulbs had short lifespans, and if the lights were wired in series they’d all be out all the time as one bulb or another burned out. Since each light had its own circuit, only the burned-out bulbs were out.

Here’s the punchline: the structural technology is not actually obsolete, although wood framing used today would have some minor differences, but the wiring technology here is no longer allowed in ordinary buildings, as it’s unsafe. To put that in context, the vast majority of obsolete structural technologies that we encounter are grandfathered, as they are not so far from modern standards that they can’t remain in use, while mechanical systems have much shorter lifespans and the older tech is most often ripped out and replaced when a building is rehabbed.

Adaptations For Use

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New York Hospital has a nice long history, dating back to a royal charter before the American Revolution. In 1932, after affiliation with the Cornell University Medical School and a number of other institutions, it moved to the building in the photo above, a skyscraper with a whole bunch of low-rise wings connected at the […]

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Thousands of Years of Western Architecture

November 5, 2017

The management is redoing the hallways in our apartment house. They’ve decided to hide the cable TV co-axial cables within a plastic crown molding. The installation is, as seen above, in progress. The original wood crown moldings were based on classical forms and were a way to hide the cracks that often develop in plaster-covered […]

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An Unseemly But Necessary Growth

November 3, 2017

There’s no mystery as to what that big thing sticking up above the roof of this building* is: it’s the top of an elevator shaft. The windows in line with the thing are all marked “SHAFT WAY,” which is a not-so-subtle hint; the fact that this is a mid-1800s commercial building that is still in […]

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Peeking Through Unsubtly

August 13, 2017

Another example of a visible piece of ordinarily hidden infrastructure. This one is as easy to spot as the bags of garbage waiting for pick-up.

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Vermiform Squared Off

June 27, 2017

If you have good eyesight, or if you click on the picture above to expand it, you’ll see three odd appendages running up the side of the building. They’re maybe two feet square in plan and go from about the fifth floor level all the way to the top. The two that flank the narrow […]

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More Than A Drop To Drink

June 19, 2017

Via David Goehring, the Ashokan Reservoir in Ulster County: Stanley Greenberg, writing for The Architectural League, took a photo of a nondescript tunnel entrance and did a nice job explaining how that concrete and steel protrusion shows our water supply system. The very short version: after a long period of New Yorkers drinking water that […]

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Shaft Drive

February 2, 2017

In a modern factory, nearly all of the machinery is powered by electric motors. It’s a clean* and almost silent way to make the machines run.** All well and good, but this is a post-1900 phenomenon. How did factories run in the nineteenth century? Shaft drive connected to steam engines. Steam engines, unlike electric motors, cannot be […]

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Creeping Systemization

September 13, 2016

Broadway and 38th Street, cut open for construction of the BMT Broadway line. Note the collection of pipes and conduits. This New York Times article on the condition of our streets and our under-street infrastructure, Why Are New York’s Streets Always Under Construction?, is a good basic explanation of the topic. There’s an interesting sidelight […]

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Clocks Now and Then

July 12, 2016

First, a truly amazing thesis project from a design student: a wooden clock that writes the time. Bad jokes aside, the big difference between structural engineering and mechanical engineering is that structural engineers working on buildings assume the objects they study are not moving (static) or move slowly enough that the effects of movement can be […]

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