GB262571A - Improvements in and relating to means for the protection of jewellers' windows and the like - Google Patents

Abstract

262,571. O'Brien, M. C. M. June 10, 1925. Burglar and like alarms. -To prevent burglary a jeweller's or like window has display shelves supported by cords 31 which are released by breakage of the glass &c. the contents of the shelves being precipitated into a cotton-wool-lined box 39 which is automatically closed and locked. An electric alarm circuit is closed at the same time as the release of the shelves. The catch 33<a> which retains the cords 31 is connected to the cover 16 of one compartment of an air-tight receptacle 11, Fig. 3. Two additional compartments 9, 10 of this receptacle are exhausted by connection to the receiver 2 of a motor driven pump 1. The compartment 9 is also connected to the exhausted space between the double panes 22, 23 or like exhausted space liable to attack and has an airtight pouch 13 connected to a valve 15 between the spaces 10, 11. The break down of the vacuum in the space 9 through the breakage of the glass &c. by releasing the valve 15 leads to the partial exhaustion and collapse of the bellows-like compartment 11 and release of the cords 31. The circuit of an alarm 20 is also closed at 18, 19. The vacuum devices according to this invention may be combined with the pressure controlled system described in Specification 231,851. The break down of the vacuum may be caused for example by breakage of a connected glass tube by a spring-controlled hammer, said hammer being normally held by a catch which is released by mechanical or electrical means as described in the Specification referred to.