99 



Graduated Glassware. The unit of capacity is the cubic centi- 

 metre volume of one gram of water weighed in vacua at 

 4 C. Volume marked corresponds to air and water 

 temperature of 15 C. Barometer pressure, 760 mm. [17, 

 21.] 



Graduating Machine. See Dividing Engine. 



Graduator. An instrument for dividing any line, straight or 

 curved, into equal parts. [10.} 



Granometer. An instrument for quickly counting seeds of corn, 

 etc. 



Granta Compression Instrument. See Extensometer. [19.] 



Granta Extensometer. See Extensometer. [8, 19.] 



Graphometer. A surveying instrument for taking angles. 

 Called also a demi-circle. [13, 17, 21.} 



Graphoscope. An optical instrument for magnifying engravings, 

 photographs, etc., usually having one large lens and two 

 smaller ones. [17, 20, 26} 



Graphostereoscope. A combined graphoscope and stereoscope 

 for viewing stereoscopic slides. [20, 26.] 



Grassot Fluxmeter. See Fluxmeter. [4.] 



Graticule. A cross-line or scale engraved on glass (or, some- 

 times, webs or platinum points), placed in the focal plane 

 of the eyepiece of an instrument for sighting or measuring 

 [1, 2, 3, 9, 10, 13, 14, 15, 16, 17, 18, 20, 22, 24, 25, 26, 27} 



Grating. See Diffraction Grating. Also Echelon and Etalon 

 Grating. [10, 14} 



Gravette Level. See Level. [13} 



Gravette Rule. See Slide-Rule. [21, 24} 



Gravimeter. An instrument for ascertaining the specific gravity 

 of bodies. See also Hydrometer. [13, 15, 17, 21} 



Gravitometer. An instrument for indicating and recording the 

 specific gravity of gas. 



Gravity Battery. See Battery. 



Gravity Bottle. See Specific Gravity Bottle. [21} 



Gravity Indicator. See Indicator. 



Gray's Flash-Point Apparatus. See Flash-Point Apparatus. [13, 

 15, 17} 



Great Circle Instrument. An instrument for giving the Great 

 Circle course and distance between any two places on the 

 earth's surface. [15, 27} 



Gregorian Telescope. See Telescope. 



Greenough's Binocular Microscope. See Microscope. [2, 3, 13, 

 26] 



Grisoumeter. A fire-damp detector invented by Mr. Coquillon. 



Growing-Cell. A form of trough for use in the miscroscope in 

 which minute living organisms can be kept alive for long 

 periods and examined continuously. [2} 



Grubb Miner's Dial. See Dial. [13, 21, 27} 



Gum-melting Thermometer. See Thermometer. [5, 21} 



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