5' 



Dictionary of 

 British Scientific Instruments. 



ISSUED BY 



The British Optical Instrument Manufacturers' 

 Association. 



The indzx numbers refer to the Manufacturers, see pages 2 and 3. 



Abacus. An ancient apparatus, consisting of beads sliding on 



wires, used for casting up accounts or performing arithmetical 



calculations. 



Abbe Condenser. See Condenser. [2, 3, 9, 17, 20, 21, 22, 26.] 

 Abbe Reiractometer. See Refractometer. [14.] 

 Abbot's Silver Disc Pyrheliometer. See Pyrhekometer. 

 Abel-Pensky's Flash-point Apparatus. See Flash-point Appar- 

 atus. [13, 15, 17, 21.] 

 Abel's Petroleum Test Apparatus. See Flash-point Apparatus. 



[13, 15, 17, 21.] 

 Abney's Clinometer. See Clinometer. [2, 5, 9, 10, 13, 15, 17, 



18, 20, 24, 25, 26, 27.] 

 Abney Level. See Level. [2, 5, 6, 9, 10, 13, 15, 17, 18, 20, 21, 



24, 25, 26, 27.] 



Abraham Projection Bheograph. See Bheograph. [4.] 

 Absorption Apparatus. An apparatus for observing the relative 



quantities of coloured rays absorbed by a medium of given 



in ckness. 

 Absorptionmeter. An instrument for measuring the absorption 



power of gases. 

 Accelerometer. An instrument for determining the acceleration 



of a moving body. [17.] 

 Accumulator. A cell or series of cells capable of being charged 



with electricity and of yielding electric current in turn, as 



the result of chemical action. Also called a storage or 



secondary cell. 

 Acetimeter. An instrument for estimating the amount of acetic 



acid in liquids. [5, 13, 15, 17, 21.] 

 Acetometer. A hydrometer (q.v.) graduated for determining the 



strength of acetic acid. See Hydrometer. [5,6,13,15,17,21, 



06.] 

 Achromatic Condenser. See Condenser. [2, 3, 9, 11, 17, 20, 22, 



26.] 

 Achromatic Lens. See Lens. [2, 3, 8, 9, 10, 11, 12, 13, 14, 15, 



17, 18, ZO, 21, 22, 23, 24, 26, 27.] 



Achromatic Prism. See Prism. [15.] 



D 2 



