I [Christopher Gray] forward this from Christopher Taverner, apparently not a
BP member.  He originally wrote me:

"I was interested to learn from your article that the AT&T building was
designed by Welles Bosworth, as I recently studied problems on the Main
Group buildings at MIT. Am curious if he used the self balanced double-hung
steel windows that he used there (top sash connected to the bottom via the
pulley mounted parallel at the top of the jamb), or whether that was a one
time design responding to the fresh-air and light gospel which John Freeman
laid down for the college. "  [That must be about 1920 - CG]


Then he responded to my query about these windows with the following:

"There were "front" windows (huge, 2 story plus intermediate glazed spandrels
and sidelights), facing Mass Ave and the Charles, and "back", (large, single
story, punched openings) in the courtyards.

Most of the failure has been rusting at the spandrels, where the detailing
doesn't work, and at the bottom rails which tend to rust when paintwork
isn't maintained. The operating mechanism is typically fine.
If a window doesn't operate, it is more likely to have been painted shut or
rusted. I can't say that the mechanism has directly impacted the longevity
of the window type. However, where a painter was casual about the upper sash
(which is common, since people rarely use them, especially  monumental
ones), the lower sash becomes too heavy to lift and the users blame the
system.  But I suppose this says something for redundant design as better
suited to homo sapiens.

Unfortunately the back windows came complete in their frame, so it is
impossible to remove sash for repair without cutting the sash! The front
windows are dis-assemblable and can be renovated.  What has worn out is the
track, which was a sherardized insert, since painting would have gummed up
the works.

The galvanization is almost gone at this point.  Modern galvanization
techniques aren't really suitable for long skinny, thin stuff that has to be
smooth, so we experimented with a Teflon coating designed for surgical
wires. It seems to do the trick. MIT are now thinking about fundraising to
carry out the renovation."