XI. TIME. 119 



460b. Wheatstone's 'Sympathetic Magneto-Electric 

 Clocks (4). The British Telegraph Manufactory, Limited. 



46Oc. 18-inch Wheatstone's Sympathetic Magneto- 

 Electric Clock. 



The British Telegraph Manufactory, Limited. 



461. New System of Electric Clocks. 



Prof. Osnaghi, Imperial Central Meteorological Institute, 

 Vienna. 



In these electric clocks the uncertainty of the action of the greater number 

 of electric pointers has been avoided by causing the electric current to flow 

 with almost unabated force, as if there were no other clocks present. This 

 is attained by giving the electro-magnets double coils of very unequal 

 resistance. The spirals with great resistance serve for the attraction of the 

 needle from a distance ; the spirals with little resistance for retaining the 

 already attracted needle. With every clock there is also a wire coil for the 

 general return current, through which the electric current can circulate until 

 the attraction of the needle is complete, when its course is diverted by certain 

 mechanism, and is forced to pass over to the next clock. 



464. Model of a Protomotive Clock. 



The Committee, Royal Museum, Peel Park, Salford. 



An apparatus consisting of a dial with hour and minute hands, and a gutta- 

 percha tube 100 feet in length, the object of which apparatus is to demonstrate 

 how a number of such dials in distant situations may be made, by means of a 

 column of air at natural pressure, to indicate the same time as the clock with 

 which they are connected. Invented and made by the late liichard Roberts, 

 C.E., Manchester, about the year 1848. 



465. Ley's Compensating Pendulum. Henry W. Ley. 



An inexpensive pendulum compensation is to be obtained by the employ- 

 ment of zinc and flint glass. 



466. Ley's Entirely Detached Gravity Escapement. 



Henry W. Ley. 



The object of this escapement is to cut off absolutely from the pendulum 

 the clock train with its variations, so that there may be nothing whatever to 

 disturb the arc of vibration. The arrangement of the escapement shown in 

 the Figs, permits the motions of the various parts to be clearly followed. 

 The scape wheel has six long teeth A, Figs. 1, 2, 3, and 4, by means of 

 which it is " locked," and six " impulse " pins B near its arbor. The arbor 

 carries a fly, not drawn. The pendulum receives its impulse at each alternate 

 beat ; at the beats from right to left in the Figures. The parts of the escape- 

 ment are : (1), a pallet C; (2), a lever D, having the same axis as C, and 

 resting normally against a fixed stop, from which it can lift, but below which 

 it cannot fall ; (it is in its normal position in Figs. 1, 3, and 4) ; (3), an arm 

 E, of which one end can turn on a pin in D, and the other end, which is free, 

 is lifted by the impulse pins, and rests on them successively ; (it is resting 

 on an impulse pin in Fig. 1) ; (4), a first detent F, against which C sets 

 when at the top of its lift; (C is thus set against F in Fig. 1); (5), a 

 second detent G ; and (6), set on a spring, a stop H, against which the scape 

 wheel locks. 



