176 



Tubular Compasses. Compasses with pen and pencil mounted 

 on a tube. [2, 5, 13, 15, 17, 21, 24, 26, 27, 28.] 



Turbidimeter. An instrument for measuring the turbidity of 

 water. [2.] 



Turn-Table. A revolving table used in mounting microscopic 

 objects. [2, 26.] 



TwaddeU's Hydrometer. See Hydrometer. [5, 13, 15, 17, 21, 28.] 



Udometer. A rain-gauge (q.v.). [13, 15, 17.] 



Ullage Rod. A rod for determining the quantity of liquid 



required to fill a cask partly filled. [5, 13, 15, 17.] 

 Ullage Rule. A rule for use with the Ullage Rod (q.v.). [5, 13, 



15. 17.] 



Unifilar Magnetometer. See Magnetometer. [13, 15, 17.] 

 Universal Portable Electrometer. See Electrometer. [4.] 

 Universal Sun Dial. See Sun Dial. 



Vaccine Apparatus. Apparatus for the preparation of vaccines 



for injection in the treatment of diseases. 

 Vacuum Gauge. See Gauge. [5, 13, 15, 16, 17, 21, 28.] 

 Vacuum Tube. See Geissler's Tube and Crookes's Tube. 

 Valentine Knife. A two-bladed knife for making at a single 



stroke a thin section of a tissue, for microscopic examination. 



[20, 26.] 



Valvograph. A simple instrument, made in transparent cellu- 

 loid, for solving without calculation various problems relating 



to valve diagrams. [13, 15, 21.] 

 Vaporimeter. An instrument for measuring the volume or the 



tension of any vapour. [13.] 

 Vaporimeter, Archbutts'. An instrument for determining the 



vapour-tension of oils. [13.] 

 Variable Power Telescope. See Telescope. 

 Variable Speed Recorder. A type of recording drum which can 



be connected to a machine to enable the speed of rotation to 



be determined. See also Revolution Counter. [4, 5, 13, 16, 



17, 19, 21, 25, 26.] 

 Varnish-Maker's Thermometer. See Thermometer. [5, 13, 15, 



16, 17, 21.] 



Velocimeter. An apparatus for measuring and ascertaining the 

 speed of machines, etc. See also Revolution Counter. 



Velometer. An air-speed indicator for aeroplanes. [15, 17.] 



Verascppe. A stereoscopic hand camera invented by Jules 

 Richard. 



Verner Rapid Sketcher. A combination instrument for military 

 work, designed by Major W. Verner ; combining a clino- 

 meter, compass, sighting rule, protractor, and plotter. 



Vernier Calliper. See Calliper. [25.] 



Vernier Compass. A Service pattern marching compass (q.v.). 

 [16, 20. 21, 27.] 



