i6o 



Spiral Compasses. A drawing compass for describing spirals. 



[13, 15, 20.] 



Spirit Compass. See Compass. 



Spirit Level. See Level. [13, 15, 16, 19, 21, 23, 24, 27.] 

 Spirit Level Tester. A device for calibrating a spirit level in 



terms of the amount of tilt corresponding to definite move- 

 ments of the bubble in the level. [21, 25, 27.] 

 Spirograph. An instrument for recording the respiratory 



movements. 

 Spirometer. An instrument for measuring the capacity ol the 



human lungs. [21.] 

 Spline Weights. An instrument for holding splines in position 



on the drawing-board. [13, 15, 17, 21, 24, 27.] 

 Splines. Flexible wooden rods of varying length and section, 



used for drawing curved lines. [2, 13, 15, 17, 21, 24, 27.] 

 Spot Lens. A condenser (q.v.) for illuminating objects on a black 



background for examination under a low-power microscope. 



[2, 3, 8, 10, 12, 20, 22, 26.] 



Spotting Telescope. See Telescope. [2, 3, 10, 13, 20, 26, 27.] 

 Sprengel Pump. A form of air-pump in which exhaustion is 



produced by a stream of mercury running down a narrow 



tube in the manner of an aspirator. [20, 21.] 

 Spring BOWS. Small compasses (q.v.) in which the head joint is 



dispensed with, the sides being tempered steel forming 



springs. 



Spy-Glass. A small telescope (q.v.). [3, 13, 16, 17, 26, 27, 28.] 

 Stactometer. A tube for measuring liquid in drops. 

 Stadimeter. A horizontal graduated bar on a staff used as a 



stadium or telemeter (q.v.) for measuring distances. [13, 



21.] 

 Stadiometer. An instrument designed to show at one reading 



the measure of any line of sight, curved or broken, on maps. 



[13, 21, 27.] 

 Stadiometer, Edgeworth's. A surveying instrument having a 



round disc plate on which a sheet of paper can be fastened, 



a divided scale with its edge passing over the centre of the 



plate enabling the observed distances around the instrument 



to be plotted to scale. [13.] 

 Stadiometer Telescope. A surveying or sighting telescope with 



an adjustable diaphragm for reading distance from the 



levelling staff. [13, 21.] 

 Stage Forceps. For holding unmounted objects on the stage of 



a microscope. [2, 3, 17, 20, 21, 22, 26.] 

 Stammer's Colorimeter. See Colorimeter. [17, 21.] 

 Standard Scale. A nickel plated divided steel scale, with certifi- 

 cate of accuracy from the National Physical Laboratory. 



[21, 25.] 



Stanhope Lens. See Lens. [2, 17, 20, 26.] 

 Star Diagonal. See Diagonal Eyepiece. [2, 3, 6, 21, 27.] 



