Telltale Switch
Description:
Patent for switch that indicates when a vacuum fails. Used for systems in "which it is desired to keep a ... uniform vacuum such as in fruit dryers, creosoting plants, surgace and jet condensing for steam plants and the like" (lines 21-25).
Date:
March 23, 1915
Creator:
Howland, John
Item Type:
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Partner:
UNT Libraries Government Documents Department