177 



Vernier Model. A model used in navigation schools for teaching 



the reading of the vernier. [15.] 

 Vernier Reading Theodolite. A theodolite (q.v.) with vernier 



reading device. [21, 24, 25.] 



Vertical Drawing Compasses. See Compasses. [15, 21.] 

 Vertical Illuminator. An apparatus for illuminating metal 



surfaces for examination with the microscope by throwing 



the light down through the objective. [2, 3, 20, 21, 22, 26.] 

 Viameter. An odometer (q.v.), called also a viatometer. [21.] 

 Viatometer. See Viameter. 



Vibration Recorder. See Seismograph. [4, 13, 17, 21, 26, 27.] 

 Vibrometer. A special form of vibration table used for testing 



compasses and instruments for the effects of vibration. [16.] 

 Vibrometer, Tuned-Reed Pattern. An instrument fitted with 



vibrating reeds of adjustable natural frequencies and 



arranged to show the extent of, and the plane in which, 



vibration is present in a turbine or other machine. 

 Vibroscope. An instrument for graphically recording the 



vibrations of a tuning-fork. 

 Vicat Needle. An accurate instrument for determining the time 



taken by cement in setting. See Cement Needle Apparatus. 



[17, 21.] 



View-Finder. See Finder. 

 Vignetter. An apparatus for printing photographs with a margin 



gradually fading away. [3, 20.] 

 Vinometer. A form of hydrometer (q.v.) for measuring the 



strength of wine. [13, 21.] 

 Viscometer. An instrument for measuring the viscosity of 



liquids. [13, 15, 17.] 

 Viscometer, Boverton Redwood's. A viscometer for determining 



the viscosity of oils. [15.] 

 Viscometer, Engler's. A standard form of viscometer designed 



by the Petroleum Congress. [15.] 

 Viscometer, Glue. A viscometer for testing the viscosity of glue. 



[21.] 



Viscometer, Redwood's Standard. Admiralty pattern. A visco- 

 meter for the determination of the viscosity of lubricating 



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

 Viscosimeter. See Viscometer. [13, 17.] 

 Visiometer. An instrument by which to determine the power 



of lenses (spectacles). 



Vitrographine Ink. Ink for writing on glass with steel pen. 

 Vivascope. A telescope for viewing objects at close ranges. [8, 



13.] 



Voltaic Battery. A galvanic battery. See Battery. [26.] 

 Voltameter. An instrument for measuring the strength of a 



current by means of electrolysis. 

 Voltameter, Silver. A voltameter in which the current strength 



is measured from the deposition of silver from an electrolyte 



M 



