[MassHistPres] 1848 iron roof structure

[Dennis De Witt]

Paul

Your query about iron leads me to ask if your group would be  
knowledgeable in anything as "new" and semi-industrialized as an 1848  
wrought iron roof system?

Somewhat to our surprise, we may have stumbled upon the oldest  
surviving, wholly-wrought-iron-trussed, roof structural system in the  
US.

It is the Brookline Gatehouse of the Cochituate Aqueduct.  This roof  
structure is most likely associated with the chief consulting  
engineer John B. Jervis or his immediate subordinates.  (Before that,  
Jervis had designed and engineered the NY Croton Aqueduct and various  
RR and canal projects.)   The engineers under Jervis, both with RR  
backgrounds, were Ellis Sylvester Chesbrough (who later reversed the  
flow of the Chicago River) &  Wm. S. Whitwell.  The architect was  
Chas. E. Parker -- at the very beginning of his career.

The roof structure consists of twenty-one, 25 ft span, four-panel  
Howe roof trusses, 24" O.C., assembled from wrought iron rectangular  
bar stock, with all riveted connections.  They support a single  
continuous structural roof deck of wrought iron plates, stitch  
riveted to each other around all four sides.  Its ridge is formed of  
a row of bent plates and the plates on either side are lapped as one  
would to exclude water run off.  They also appear to have been  
tarred.  We believe the eve edge is integral with a built-in gutter  
(now failed) above the walls and behind the granite eves.  There is  
presently a standing seam roof over it and, except at the walls,  
there seems to be little leakage.  The trusses definitely have their  
problems, but so far none have fallen and the assemblage remains  
standing.

Originally, the trusses supported a plaster ceiling, which also made  
them invisible.  It is now gone.

Although this "iron roof" is mentioned in official reports of the  
time, we thus far have found no evidence that it was ever published  
in any professional or technical publications.   The gatehouse at the  
upper end of the aqueduct at lake Cochituate also reportedly had an  
iron roof of a somewhat different design (hipped).  But it was  
replaced in the 19th c. — possibly in 1859.

The only built US wrought iron predecessor roof trusses that we can  
identify were said to be in the first retort house of the  
Philadelphia Gas Works ca. 1837 -- now long lost.  Strickland's 1841  
book, Public Works says they immediately suffered corrosion  
problems.  It has a plate which purports to show them, but close  
examination of the drawing raises some questions.  Rightly or wrongly  
and without explanation, Condit discounts them.  Talbot Hamlin  
praises Stickland's book but curiously doesn't mention the trusses  
nor the startling Greek Revival building [project?] which contained  
them.

There are references to earlier "iron roofs" in Peterson and  
elsewhere but either they are too vague to verify or, more often,  
close reading seems to suggest that they were only non-self- 
supporting sheet metal roof coverings.

This small building also contains a mirror image pair of delicately  
pierced cast iron stairs.  Thus far, we have not identified any other  
cast iron staircases of this date in the US, other than in more  
functionally explicable settings — specifically in two or three  
penitentiaries in Pa. & NJ and in a few lighthouses.  It has been  
suggested that these stairs might have been imported from the UK.

We would be interested in connecting with any additional experts in  
early industrialized wrought iron technology or anyone who might shed  
any light on any of the above.  Thus far we have not found much  
documentation in the MWRA archives.  (Sara Wermiel an historian of  
early iron fireproof construction at MIT has been through the building.)

Best regards,

Dennis De Witt