52 



Achromatic Telescope. See Telescope. [2, 3, 8, 9, 10, 11, 13, 15, 



17, 18, 20, 21, 22, 23, 25, 26, 27, 28.] 

 Acidimeter. An instrument for determining acidity in cheese or 



butter. [6, 8, 13, 15, 17. 21.] 

 Acidimeter. See Hydrometer. 

 Ackermann's Calculating Disc. For the rapid determination of 



alcohol and extract contained in beer. 

 Acoumeter. An instrument for measuring the acuteness of the 



sense of hearing. 

 Acousimeter. An acoumeter. 

 Actinograph. An instrument for recording the variations of 



chemical influence of the solar rays. 

 Actinometer. An instrument for measuring the actinic powers 



of the sun's rays. In photography for determining the 



sensitivity of a photographic plate or paper. [17, 20, 21, 26.] 

 Acu-puncturator. An instrument used in the examination and 



treatment of the skin. 

 Acutometer. An instrument for determining the degree of 



vision with exactness and rapidity. It consists essentially 



ol a device whereby a straight black line can be gradually 



widened, [2, 9.] 

 Adding Machine (Burrough's). A machine which prints a 



column of figures in s. d. and automatically their sum. 



[15, 20.] 

 Adeney's Apparatus. For experiment with and analysis of 



dissolved gases. 

 Adeney's Apparatus. For recording the rate of absorption of 



oxygen by polluted water, and generally for the extraction 



and collection of gases dissolved in water. 

 Adjusting Cone. An instrumenc for measuring the distance 



between the axes of the eyes. 



Adjusting Dial. See Dial and Pelorus. [13, 15, 16, 17, 28.] 

 Admiralty Chart Table. The special form used on ships of the 



Royal Navy. [13, 15, 16, 17.] 



Admiralty Clinometer. See Clinometer. [13, 15, 16, 17, 21.] 

 Aero Clinimeter. See Clinometer. [6, 9, 15, 16, 17, 21.] 

 Aero Compass. See Compass. [13, 15, 16, 20.] 

 Aerodynamic Balance. See Balance. [4.] 

 Aerograph. (i) A general term for any instrument recording 



any of the properties of the air. (2) An instrument or tool 



for spraying with colour, enamel, CLC., a surface or object 



by means of air pressure. Termed also an Aerograph Brush 



or Pencil. [16, 17, 21, 27.] 

 Aerometer. Any instrument for measuring the weight and 



density of air and gases. [15, 17, 21.] 

 Aerophone. An invention of Edison for amplifying sound. 

 Aeroplane Instrument Board. A light and compact aluminium 



frame or board carrying the various instruments used on 



the aeroplane. [4, 6, 15, 16, 17, 19.] 

 Aeroplane Revolution Indicator. See Indicator. [4, 6, 9, 15, 17 n 



