70 



precision intervals of time, usually up to 30 minutes. See 



also Electro-Chronograph. [4, 11, 13, 15, 16, 17, 21, 24, 25, 



26, 27.] 

 Chronometer. A specially accurate timepiece for use in nautical 



and astronomical observations. [13, 15, 16, 17, 20, 21, 24, 



25, 27, 28.] 

 Chronopher. An instrument for signalling by electricity the 



correct time to distant places. 

 Chronoscope. An instrument for measuring minute intervals of 



time, used in determining the velocity of projectiles, the 



duration of short-lived luminous phenomena, etc. [17, 27, 



28.] 

 Chronothermometer. Consists of a circular thermometer with a 



watch movement in the centre, with a hand which revolves 



over the thermometer scale at the rate of 20 Fah. in 15 



minutes. Used for testing petroleum by measuring the 



heating power of a flame. [13, 15.] 

 Chyometer. An instrument for measuring liquids. It consists 



of a piston moving in a tube in which is contained the liquid 



the quantity expelled being indicated by graduations upon 



the piston rod. 

 Cinematograph. An apparatus for rapidly projecting on a 



screen a series of consecutive instantaneous photograplis, in 



such a manner as to give the impression of a moving object. 



[2, 3, 8, 20.] 



Circuit-Breakers. See Mine-Explosion Apparatus. [4.] 

 Circular Micrometer. An annular form of the micrometer, first 



suggested by Boscovitch in 1740, and afterwards revived by 



Olbers in 1798. [8, 11] 



Circumferentor. A surveying instrument for measuring hori- 

 zontal and sometimes vertical angles. [2, 13, 15, 17, 18, 20, 



21, 24, 25, 26, 27.] 

 Cistula. See Catoptric Cistula. 

 Claude Lorraine Glass. A black glass convex mirror, used for 



sketching, to give a monochromatic view of scenery. [2, 3, 



17.] 

 Clepsydra. A kind of water-clock or an hour-glass serving to 



measure time by the fall of a certain quantity of water or 



other substance, commonly out of one vessel into another. 

 Clift Air-Speed Indicator. A speed instrument for aeroplanes. 

 Clift Petrol-Tank Gauge. See Petrol-Tank Gauge. 

 Climatometer. An instrument for indicating the fluctuations of 



temperature with special reference to its perception by 



the human body. [13.] 

 Climb Meter. An instrument to indicate and measure the rate 



of the rising of an aeroplane. [15, 17, 21.] 

 Clinical Thermometer. See Thermometer. [2, 5, 6, 9, 13, 15, 



16, 17, 20, 21, 24, 25, 26, 27, 28] 

 Clinograph. An adjustable set-square, useful when a number of 



lines are required at an angle to the base line other than 



