163 



Suncap. A tinted glass used between the eye and eyepiece of 

 a telescope when viewing brilliant objects. [2, 3, 10, 13, 

 21, 26.] 



Sun-Dial. An hour-dial with gnomon, the shadow of which, 

 falling on the dial, indicates the time. [2, 6, 9. 10, 13, 15, 



16, 17, 18, 20, 21, 24, 26, 27.] 



Sun-Dial, Universal. A form of sun-dial which can be set for use 

 in all latitudes. [13, 15, 17.] 



Sunglass. A convex lens of glass for producing heat by con- 

 verging the sun's rays to a focus. [3, 6, 13, 15, 21, 26.] 



Sunshine-Recorder. An optical instrument for recording the 

 duration of sunshine by a burning-glass or by a simple form 

 of photographic camera. [2, 4, 5, 6, 9, 10, 13, 15, 17, 20, 21, 



24, 25, 26, 27.] 



Sunshine-Recorder, Campbell Stokes's. A standard form of 



sunshine-recorder of the burning-glass type. [6, 10, 13, 17, 



20, 21, 26, 27.] 

 Sunshine-Recorder, Whipple-Casella. A universal instrument of 



the burning-glass type, using only one size of card instead 



of three. [<?.] 

 Superheater Thermometer. See Thermometer. [5, 13, 15, 16, 



17, 21.] 



Surface Gauge. An instrument for testing the trueness of a 

 surface. 



Surveying Level. See Level. 



Sutcliffe Keratometer. See Keratometer. [26.] 



Sutherland's Protractor. See Protractor. [13.] 



Switch. A mechanical device for passing an electric current to 

 another circuit. [16, 26.] 



Switch Scale. A transparent scale divided to 6,000 yards, on 

 scale of 1/10,000 with a pinhole of scale ; for pivoting over 

 gun position ; used for gunnery work. Also a boxwood 

 scale for use with radian arcs. [2.] 



Sygmograph. See Cardiosygmograph. [21.] 



Sympalmograph. An instrument for making Lissajou's sound- 

 curves. 



Sympiesometer. An instrument for measuring the weight of 

 the atmosphere by the compression of a column of gas. 

 See also Barometer, Boylean Mariotte. [13, 27, 28.] 



Syphon Barometer. See Barometer. [6, 10, 13, 17, 21, 26, 27, 

 28.] 



Tabor Indicator. See Indicator, Engine. [13, 15, 16, 24.] 

 Tacheometer. A transit theodolite (q.v.) having a distance- 

 reading device in the telescope. [2, 13, 15, 17, 18, 21, 24, 



25, 26, 27.] 



Tachograph. A recording tachometer. [13.] 



Tachometer. (i) An instrument for measuring the velocity of 



machines. (2) An instrument for measuring speeds without 



timing. [5, 13, 15, 17.] 



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