9 8 



Gimbal (Gimbol). A form of universal joint for securing free 



motion in suspension, or for suspending anything, as a 



lamp, a compass, a chronometer, etc., so that it may always 



retain a certain position or be in equilibrium. [13, 15, 16, 28.] 

 Girthing Strap. A strap used for measuring the girth or 



dimensions of timber. [17, 21, 24, 27.] 

 Girt Tape. A broad strong tape for measuring the perimeter 



or girth of timber. [5, 21, 24, 27.] 

 Glass. See Optical Glass. 

 Glass Hydrometer Jars. Glass jars used in oil-testing and for 



other purposes. [5, 13, 15, 17, 21, 28.] 

 Glaucometer. See Gleucometer. 

 Gleucometer. An instrument for measuring the sp. gr. and 



ascertaining the quantity of sugar contained in must 



(the expressed juice of the grape or other fruit before 



fermentation). [13, 21.] 

 Globulimeter. An instrument for measuring the number of 



red corpuscles in the blood. The method depends on the 



differences of tint obtained by mixing a sample of blood 



with sodium carbonate solution. [21.] 

 Glue Viscoraeter. See Viscometer. [21.] 

 Glycerine Barometer. See Barometer. 

 Glyphoscope. A stereoscopic hand camera invented by Jules 



Richard. 

 Gnomon. The index or style of a sundial. Formerly a style 



or column erected perpendicularly to the horizon, used in 



astronomical observations by observing the length of its 



shadow. 

 Goggle. A special form of spectacles for preserving the eyes 



from wind, dust, and exposure to strong light. [2, 9, 13, 15, 



17, 18, 20, 21, 26, 27, 28.] 

 Goniometer. An instrument for measuring angles and especially 



those of crystals : the reflecting goniometer and the double 



image goniometer. [1, 2, 3, 13, 14, 17, 19, 20, 21, 22, 25, 26.] 

 Goodman's Averaging Instrument. See Averaging Instrument. 



[1ft,] 



Goodman's Planimeter. See Planimeter. 

 Gradient Indicator. See Indicator. [6, 15, 16, 17.] 

 Gradient Telemeter Level. See Level. [13, 17, 18, 21, 24, 25, 



27] 

 Gradienter Screw. A micrometer screw (q.v.) fitted to a tangent 



arm which can be clamped to the trunnion of a telescope or 



theodolite. [6, 18, 24, 25, 27] 



Gradimeter. A special form of surveying level (q.v.). [18. 25.] 

 Gradiometer. An instrument which, while performing all the 



duties of a first-class level, is designed also for taking vertical 



inclines at small fixed angles ; for railways, drainage works, 



etc. [13, 17, 18, 21, 25] 

 Gradioplane. An instrument specially designed for very accurate 



underground surveying. [13, 21.] 



