E. Howard Watch Co. (Keystone) Series 0

The Model 1907 Series 0 was originally manufactured with a jeweled safety barrel, covered by U.S. Patent #886387 (Issued May 5, 1908). The initial model design featured a straight-finger train bridge for the 4th and escape wheel, reminiscent of the movements Waltham had produced for the E. Howard Watch Company prior to the introcution of the Model 1907. This design was altered c.1911 to a “hooked” finger profile, accommodating the newly-patented end stone caps for the escape wheel and pallet fork, an iconic feature throughout the remainder of the Series 0 production. When the train bridge design was updated, the jewels were changed from pressed raised gold settings to friction-set (with the exception of the escape, pallet, and balance jewels). Early examples are signed with “E. Howard Watch Co. Boston U.S.A.” in script with gilt or black enamel inlay. This signing style was updated to a black-inlay serif design around the time the jeweled safety barrel was retired, c.1912. When the company decided to transition to the from the jeweled safety barrel to the going barrel, jeweled banking pins were added to maintain the jewel count of 23. In addition to the absence of the jeweled barrel, most movements equipped with the going barrel are marked “Pat’d ’10” instead of “Pat’d ’08,” since the new barrel design was covered by U.S. Patent #978613 (Issued December 13, 1910). Around the time of this transition, the company also began marking “Series 0” on the barrel bridge in addition to the standard “Cross in Circle” arrow emblem on the center bridge.