Sweet’s indexed catalogue of building construction for the year 1906 (1906)
New York : Chicago : Architectural Record · leaf 357
^^r 3 Metal for wear, Soft needed, and is the best material ^^^^-^^Jr^^J^J^J^^Jm^ Metal to hold the foot known for repairs. It is used upon outer and inner stairs of granite, marble, cement, slate, iron and wood; upon the thresholds of doors and elevators, fire doors, inclined passages, vaultlight… … Fig. 2. MASON SAFETY TREAD SHOWING NOSING EDGE
Building materials
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