Sweet’s indexed catalogue of building construction for the year 1906 (1906)
New York : Chicago : Architectural Record · leaf 554
Fig. 3. NORWALL AIR AND VACUUM VALVE, ACTUAL SIZE (Pat. Feb. 9, 1904) Fig. 4. 77ic fhrau// Si^femtbamiTv Secant JB:atinff A SINGLE-PIPE SYSTEM OF VACUUMSTEAM HEATING that the entire system can be operated either under pressure or under vacuum at willby the operator. This system is designed for use…
Building materials
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