XI. TIME. 101 



inches (140 mm ) an inverted funnel about 0-63 inches (16 mni ) long, 0'27 

 inches (7 mm ) wide at its base, and about 0-04 inches (l mm ) at the upper end. 

 The lower end of the upper syphon is supported at about 0-12 inch (3 min ) 

 above the top of the funnel carried by the pendulum when at rest. A tube of 

 about 0'08 inches (2 mm ) in diameter, and 0*4 inches (10 mm ) long, is 

 supported with its upper end about 0' 12 inches (3 mm ) below the lower end 

 of the funnel at rest. 



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 earned 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 second second of time by means of a timepiece 

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

 water clock. 



The figure exhibits the action of the water on the pendulum. No attempt 

 has been made to exhibit the counting of the seconds. 



488a. Model of Compensation Balance, applicable to 

 watches and chronometers. (With a drawing.) 



M. Winnerel, Paris. 



488b. Model of Escapement, applicable to the model 

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



M. Winnerel, Paris. 



488c. Model of Escapement, with simplified suspension, 

 applicable to clocks. (With a drawing.) 



M. Winnerel, Paris. 



488d. Drawings of a Simple Counter, and of a Registering 

 Counter. 



(See Report of Baron Seguier to the Society of Encouragement, 

 1844.) M. Winnerel Paris. 



489. Standing Pendulum Clock, in black wooden box with 

 silvered dial. Professor Buys-Ballot, Utrecht. 



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

 with cycloidal 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 topped-off wooden column covered 

 by a circular brass plate, by lifting which you see the dial. 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 you 

 withdraw your finger. In this manner very short lapses of time can be 

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

 specimens were used by Holland van Beek 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) . 



