77 



Counter, Engine. An instrument for counting the number of 



revolutions or strokes of an engine or machine. [5, 13, 15, 



16, 17, 21, 28.] 

 Course-Corrector. An instrument of the Pelorus (q.v.) type for 



determining compass deviations. [13, 15, 16, 28.] 

 Course-Indicator. A combination of straight-edge and pro- 

 tractor for use with sea charts. [15.] 

 Course-Setter. Capt. Aamundsen's patent. An instrument 



designed for rapidly and accurately correcting courses, 



bearings, azimuths, etc. 

 Crack Micrometer. See Micrometer. [4.] 

 Craniometer. An instrument for measuring skulls and bones. 



[2, 21.] 



Creagh-Osborne Compass. See Compass. [13, 15, 16, 20, 26, 27.] 

 Creagh-Osborne Protractor. See Protractor. [13, 15, 20, 26, 27.] 

 Cremometer, Chevalier's. A graduated jar for the measurement 



of cream. 

 Crookes's Tube. A vacuum tube of glass fitted wth electrodes 



for the discharge of electric current. 

 Crosby Indicator. See Indicator. [13, 15, 16, 17.] 

 Cross-Head. A brass octagon with sights on each face, used 



by surveyors for setting out angles. [2, 3, 13, 15, 17, 20, 



21, 24, 25, 26, 27] 

 Cross-Staff. An ancient instrument consisting of a wooden bar 



with a divided scale, with a wooden cross-bar fitted to and 



moveable along the other, by means of which the navigator 



could measure the angle of altitude of the sun above the 



horizon. See also Fore-Staff. 

 Cryophorus. An instrument used to illustrate the freezing of 



water by its own evaporation. [21.] 

 C.S.I. Air-speed Indicator. A speed instrument for aeroplanes. 



See Speedometer. [21.] 



Cup Anemometer. See Anemometer. [15, 17, 20, 21, 24, 25.] 

 Cupel-Pyrometer. See Pyrometer. [4.] 

 Current-Meter. An instrument for measuring the velocity of 



currents of water, consisting of a screw geared to a divided 



dial, or other measuring device. [2, 6, 13, 15, 17, 21, 24, 



25, 27.] 

 Current-Regulator. An electrical device for regulating the 



intensity of the current allowed to pass a given point. [16.] 

 Current-Slide. A slide placed upon the stage of the microscope 



in which a current of fluid can be made to pass across the 



field of the microscope. [3, 13, 26.] 

 Curvature of Spherical Surfaces Apparatus. For determining 



the curvature of spherical surfaces. Designed by Dr. Searle, 



Mr. Aldis, and Mr. Dobson. [1, 3, 19.] 



Curve Pen. A pen used by draughtsmen in the drawing of 

 curves. [2, 5, 6, 9, 13, 15, 17, 20, 21, 24, 27.] 



