Sweet’s indexed catalogue of building construction for the year 1906 (1906)
New York : Chicago : Architectural Record · leaf 470
fFidtli of back plate from4 to t;i. Requiresfrom i to 3 headroom above back plate. Fig. 6. Device for moving 2 or 3 doors in same direction at varying speed, so that ail are open, or all are closed at the same time Elevator Door Lock (Fig. 6). With this lock thereis no projection of the Latch…
Building materials
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