118 SEC. 3. MEASUREMENT. 



No. 16,175, gold, open face, 21 lines, keyless. 



No. 16,873, 18 



No. 16,144, Chronographs, 19 lines, keyless. 



No. 16,534, hunter, 21 lines, keyless. 



No. 16,576, 19 



No. 16,525, 18 



457. Regulator Clock, filled with the Exhibitor's new patent 

 gravity escapement, having no upward locking, and which cannot 

 trip or slip teeth. Alfred John Higham. 



On the escape wheel there are two sets of teeth, one set longer than the 

 other ; the teeth of each set are arranged, and the pallets are formed and 

 placed, so that the shorter set of teeth only is used, except in case of tam- 

 pering or other disturbance, when the longer set comes into action. This 

 secondary locking entirely prevents irregularity in the clock rate, but the clock 

 can be allowed to " run," if it is desired to be so set to time, by removing two 

 extra stops which are adjustable. The action of the escapement is ordinarily 

 exactly the same as that of the gravity escapements invented by Mr. Denison 

 (Sir Edmund Beckett, Bart.), and the secondary locking can be applied to 

 those escapements. For further description, see the Horological Journal, 

 April 1876. 



458. Regulator, with improved gravity escapement on the 

 Bloxamic principle, as arranged and patented by Mr. Higham ; 

 founded on the old pin- wheel escapement, and fitted with a gal- 

 vanic interrupter for chronographical and other astronomical 

 purposes. Charles Frodsham $ Co. 



459. Marine Chronometer, fitted with a galvanic inter- 

 rupter for chronographical and other astronomical purposes. 



Charles Frodsham fy Co. 



459a. Two-day Marine Chronometer, fitted complete for 

 ship's use. Charles Frodsham. 



460. Apparatus for demonstrating the application of the 

 pendulum to the clock, at the same time serving for audibly indi- 

 cating the minutes. 



The Secondary Government School, Assen (Netherlands). 



This apparatus is constructed by C. H. Van der Heydeu, watchmaker, at 

 Assen (Netherlands), in conjunction with Dr. A. Van Hasselt, teacher at 

 the school for middle-class education, Assen. Price about 4/. The escape- 

 ment may be pulled forward so as to allow the wheel to turn freely. In this 

 manner it may be demonstrated, that clockwork without a pendulum will 

 acquire an accelerated motion. 



The escapement must be kept in a forward position, until the weight has 

 reached the ground. 



The apparatus, as it audibly indicates the minutes, may also be used for 

 experiments to demonstrate the laws of the pendulum, the laws of hydro- 

 dynamics, &c. 



460a. Wheat stone's Motor Magneto-Electric Clock 



(in teak case). The British Telegraph Manufactory, Limited. 



