Watchmen's Time Detectors Operated by Batteries or Magneto Generators
A trade catalogue issued about 1900 by the Holtzer-Cabot Electric Company of Boston, listing watchmen's time detectors, annunciators, electric bells and gongs for building owners, contractors and electricians. Wood-engraved and halftone cuts show apparatus head-on against plain grounds: numbered contact dials, exposed coil pairs on cast frames, domed gongs, and boxed push buttons, with dense ruled hatching that suits diagram borrowing, silhouette cutouts and mechanical spot illustration.
