64 



Clemens Riefler, Miinchen and Nessehvang. 



The essentiality of the escapement of this entirely new chrono- 

 metric system, which has also been applied to watches and tower clocks, 

 consists in the manner in which the pendulum, which is absolutely 

 free, is impelled. This is not effected, as is usually the case, by the 

 fork (this is entirely absent), but by the pendulum spring. The 

 latter is, by the action of the wheel work, slightly 

 deflected, the center of t*he deflection coinciding with 

 the axis of oscillation of the pendulum. 



The impulse is, moreover, given nearly at 

 the moment, in which the pendulum passes the 

 position of rest and the supplementary arc of 

 the pendulum is 3 or 4 times as large as the 

 arc of elevation; besides, the number of moving 

 parts is less than with any other escapement. 



The advantages resulting from the whole arran- 

 gement are these: Changes in the magnitude of the 

 transmitted force and the resistance of the pallet action 

 have no practical influence upon the uniformity of the 

 movement, and the chronometer is in a high degree 

 insensible to extraneous disturbances. 



The Mercurial Compensating Pendulum, 

 shown in the annexed figure, has also been devised 

 by Mr. S. Riefler. Its main body consists of a heavy 

 metal disc of such a lenticular form as to freely cut 

 through the air. A Mannesmann steel tube of 16 mm- 

 ? bore and 1 mm thickness constitutes the pendulum rod. 

 | Nearly two thirds of the tube are filled with mercury. 

 ^ In consequence of this distribution of a small quantity 

 e of mercury over a great length, inequalities of the 

 ! temperatures of the upper and lower layers of air and 

 ^ also sudden changes of temperature have only a slight 

 influence upon the pendulum and the movement. 



Unlike all other pendulums, it does not necessi- 

 tate a subsequent correction of compensation, as in 

 this case the latter can be calculated with greatest 

 possible precision. 



Every pendulum made by this firm is, there- 

 fore, warranted to have in no case an error 01 

 Riefler's Mercurial compensation exceeding ^ o,oo5 seconds per 



Compensation-Pendulum. ,. , _i_ n /~ 



diem and per ; i C. 



The principal | advantage of this system, i. e. the escapement in 

 conjunction with thejpendulum, consists in the increased uniformity 'of 

 the movement thereby obtained and in that the latter does no more 

 depend upon fortuitous circumstances but admits of strict computation. 



With the astronomical clocks supplied by the firm the warrant- 

 ed degree of accuracy is i second per week, and with chronometers 

 intended for use as standard clocks for private establishments or for- 



