These were introduced in 1945 and continued in production (at their Braintree, MA facility) until the late 1950s when solid-state controls superceded. The latter were much simpler and had a twistlock receptacle. "Bell Jar" glass-covered photocontrols as shown were rather commonplace for street lighting applications here in Massachusetts, especially within New England Electric service territories, notably the former Massachusetts Electric Company who serviced many towns and cities north and south of Boston. Adaptor kits offered by Fisher-Pierce around 1960 allowed quick upgrading/socket-conversion to the then-new solid-state photoelectric twist-lock controls. Most were changed out during fixture servicing. Between that and upgrading to newer light sources since 1960 make the photographed controls rare nowadays. The "seeing-eye" element was an IP-39 tube, just fyi. Click "Previous" for an internal view of this controller. Units as shown mostly were rated at 5 amperes and operated individual mercury vapor lights. These controls sometimes were mounted atop utility poles and really stood out as I fondly remember! In other instances they were mounted on crossarms or adjacent (lower on the pole), thus not quite so vividly seen...