Sweet’s indexed catalogue of building construction for the year 1906 (1906)
New York : Chicago : Architectural Record · leaf 537
rt, frostand snow in winter, when they are placedoutside the building. The Perfect FreshAir Inlet Valve removes all those objectionsby being placed inside of the building. Theseal of The Perfect Fresh Air Inlet Valveis made by liquid mercury which insures apositive and permanent seal against… … THE PERFECT FRESH AIR INLET VALVEDetail Showing Construction
Building materials
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