Cyclopedia of architecture, carpentry, and building : a general reference work (1912)
American Technical Society · Chicago : American Technical Society · leaf 401
Fig. 20. Heavy Bronze SpringBiitt. … Fig. 21. Common Type of Spiral Spring for Doors. Double=Acting Butts. The function of the double-acting buttis to allow the door to swing to both sides of the jamb. It is neces-sarily of the spring-butt type, above mentioned, but is double and is soset as to leave the door shut when at rest. There…
Architecture · Building
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