159 



parallel beam of the light to be examined, a prism to produce 

 a spectrum, and a telescope to view the spectrum. [2, 3, 

 11, 13, 14, 19, 20, 22, 25, 26.] 



Spectroscope, Beck-Thorp Pocket Diffraction. A pocket spectro- 

 scope in which a diffraction grating is employed to produce 

 the spectrum. 



Spectroscope, Direct Vision. A spectroscope, with direct vision 

 prism (q.v.) giving an undeviated spectrum. 



Spectroscope, Evershed. A spectroscope invented by Evershed 

 for the examination of the spectra of star prominences. 



Spectroscope Stand. For small spectroscopes. [14, 26.] 



Spectroscope Table. The rotating table on which the prism 

 stands. [14.] 



Speculum. (i) A mirror or looking-glass ; especially a metal 

 mirror. (2) A reflector of polished metal used in astronom- 

 ical telescopes. (3) In surgery, an instrument for dilating 

 certain of the passages, in order to admit of examinations or 

 access of instruments for operation. [1, 2, 3, 11, 14.] 



Speed Recorder. An instrument for recording the speed of a 

 motor-car, etc. [5, 6, 13, 15, 17.] 



Speedometer. See Speed Recorder. [5, 6, 13, 15, 17.] 



Spherograph. An instrument invented for the mechanical 

 application of spherics in navigation. By its aid with a 

 ruler and index the position of a ship at any place and the 

 distance sailed may be readily and accurately determined. 

 [13, 15.] 



Spherometer. A delicate instrument for measuring the diameter 

 of spherical bodies, and the curvature of spherical surfaces, 

 as of lenses. [1, 2, 3, 4, 17, 19, 22, 25, 26.] 



Spherometer, Aldis. An improved form of spherometer, designed 

 by Mr. A. C. W. Aldis, for the determination of the radius 

 of curvature of a lens. [1.] 



Spheroscppe. A large model for illustrating and teaching 

 nautical astronomy. [15.] 



Sphygmograph. An instrument used for recording on a chart 

 the character of the movements of the pulse. [21, 26.] 



Sphygmometer. The name for any instrument for measuring 

 and recording the movements of the pulse. [21, 26.] 



Sphygmomanometer. See Sphygmometer. [26.] 



Sphygmophpne. An instrument devised to enable a person to 

 determine the rhythms, etc., of the pulse at a distance by 

 means of an electric wire. 



Sphygmoscope. An instrument for rendering the movements of 

 the pulse visible. [26.] 



Spinney's Rapid Viewer. An instrument for repetition examina- 

 tion of interchangeable parts for measuring thickness of 

 material to o-ooi inch. 



Spinthariscope. An instrument for making radium emanations 

 visible to the eye. [2, 3, 17, 21, 26.] 



