XI. TIME. 127 



The pendulum being made to vibrate through a small arc before reaching 

 the upper syphon takes up a drop, and on arriving near its lowest point 

 delivers a drop to be carried off. The time is thus measured without allowing 

 the pendulum to come in contact with any solid body except the agate plane 

 on which it is supported. 



The drop given off by the lower tube at the end of every two seconds, may 

 be used to record every alternate second of time by means of a timepiece 

 having a very light pendulum timed in accordance with the pendulum the 

 water clock. 



No attempt has been made to exhibit the mechanism for counting the 

 seconds. 



48 8a. Model of Compensation Balance, applicable to 

 watches and chronometers. (With a drawing.) 



M. Winner -cl, Paris. 



488b. Model of Escapement, applicable to the model 

 clock at the Paris Observatory. (With a drawing.) 



M. lYinnerel, Paris. 



488c. Model of Escapement, with simplified suspension, 

 applicable to clocks. (With a drawing.) 



M. Winner el) Paris. 



483e. Two Movements for Chronometers, one eight days 

 and one two days. Victor Kullbcrg. 



489. Standing Pendulum Clock, in black wooden box with 

 silvered dial. Professor Buys-Ballot. Utrecht. 



This is one of the first clocks made after Huygen's principle (i.e., provided 

 with cyeloidal pendulum). This peculiarity may be seen by opening the 

 door. 



490. Two Conical Pendulum Clocks, for determining short 

 time intervals. Professor Buys-Ballot, Utrecht. 



Each of these clocks is contained in a truncated wooden column covered 

 by a circular brass plate, by lifting which the dial may be seen. The foremost 

 part of the box can be removed to put the pendulum in motion, the spring 

 being woundup. In this condition only one hand moves. By pressing on the 

 button at the foremost part of the dial, the two other hands move until the 

 finger is withdrawn. In this manner very short lapses of time can be 

 measured. The instruments must be placed accurately horizontal. These two 

 specimens were used by Moll and van Beelt on the heath near Amersfoort 

 for determining the velocity of sound. They are constructed for the decimal 

 division of time, and indicate the ten millionth part of a day (24 hours). 



491a. Very curious Timepiece, designed by Mudge. 



E. Dent and Co. 



The escapement is a true remoutoire ; two small pendulum springs are 

 wound up at every beat of the scape wheel, and these give impulse to the 

 balance. The balance is controlled by two pendulum springs, one above and 

 the other beneath it ; the first of these receives the action of the " compen- 

 " sation curb," the second is for ordinary regulation. TJie action of the 



