GON 



GR A 



GOLD LEAF ELECTROMETER. 

 An instrument for detecting the presence 

 of electricity by the divergence of two 

 slips of gold leaf. 



GOLDEN NUMBER. At the end of 

 every nineteen years, the new and full 

 moons happen at very nearly the same 

 times of the year. The ancients ascer- 

 tained this fact, and reckoned the nine- 

 teen years, or " cycle of the moon," as it 

 is called, so that it terminated the year 

 before the Christian era. This cycle was 

 marked by the Greeks with letters of 

 gold. Therefore, to find the golden 

 number, or number of the year in this 

 cycle, add 1 to the date ; divide by 19 ; 

 the quotient is the number of cycles of 

 the moon since the birth of Christ, and 

 the remainder is the golden number. 

 Thus, 1847 + 1 = 1848. Divide by 19, and 

 the quotient is 97 cycles, and 5 remain- 

 ing, which is the golden number for 

 1847. 



GOLDEN SULPHURET. A sulphu- 

 ret of antimony, also termed sulphanti- 

 monic acid, and prepared by precipitating 

 antimonic acid by sulphuretted hydro- 

 gen. See Kermes Mineral. 



GO'MPHOLITE (y^M^of, anail, X/^of, 

 a stone). A term applied by Brongniart 

 to conglomerate rocks of the tertiary 

 series, called by the Swiss Nagelflue. 



GONG. Tam-tam of the Chinese. A 

 highly sonorous species of cymbal, con- 

 sisting of an alloy of about 80 parts of 

 copper and 20 of tin. 



GO'NGYLI (yoYYuXo?, round). The 

 granules contained in the shields of 

 lichens, supposed to be the spores by 

 which the plants are propagated. The 

 term gongylus is also applied to a round 

 hard body, which falls off from the 

 mother plant in some of the algaceae, 

 producing a new individual, as in the 

 fuci. 



GO'NIATITES {fu>via, an angle) The 

 name of some spirally twisted species of 

 cephalopods which inhabited the seas 

 during the Carboniferous period, and are 

 characterized by the angular markings 

 made by the intersections of the walls of 

 the chambers and the outer shell. 



GONIO'METER. An instrument for 

 measuring angles, particularly those of 

 crystals. 



GONIO'METRY (yoji/m, an angle, jue- 

 Tpeo), to measure). " The measurement 

 of angles ; a name which should be sub- 

 stituted for trigonometry, if it were ad- 

 visable to alter established designations. 

 The latter science, beginning with the 

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measurement of triangles, made all that 

 was known of the analysis of angular 

 magnitude its own peculiar instrument. 

 The various accessions which real gonio- 

 metry received were, therefore, consi- 

 dered as additions to trigonometry; so 

 that, at this day, under a word which 

 imports measurement of triangles, we 

 have a science which wanders as far 

 from the etymology of its name as geo- 

 metry does." — Penny Cycl. 



GO'NOPHORE {ySvof, offspring, 0epa), 

 to bear). The name given by De Can- 

 dolle to a prolongation of the receptacle, 

 which elevates itself from the base of the 

 calyx of certain flowers, and bears the 

 numerous stamens peculiar to these 

 plants, as in Anonacea? and Magnoliaceae. 



GO'NOPLA'CIANS {yatvia, an angle, 

 n\a^, a plate). A tribe of brachyurous 

 crustaceans, named from the genus gono- 

 plax, and characterized by the square or 

 rhomboidal form of the carapace, or 

 upper crustaceous plate, and by the 

 length of the eye-stalks. Some species 

 of the gonoplax are fossil. 



GORGO'NIA NOBILIS. Red coral; 

 a substance consisting of an interior 

 stem of gelatinous matter and carbonate 

 of lime, and an external coating of mem- 

 brane, carbonate of lime, and colouring 

 matter. 



GOULARD'S EXTRACT. A satu- 

 rated solution of subacetate of lead, ob- 

 tained by boiling powdered litharge in 

 vinegar. 



GO'VERNOR. A piece of mechanism 

 applied to steam-engines and other ma- 

 chines, for the purpose of equalizing 

 their motion. 



GRACULFNiE [graculus, a jay). Gra- 

 culine birds, or Grackles ; a term adopted 

 by Macgillivray instead of that of 

 Thremmaphilince, and applied to a group 

 of birds, allied to the Crows on the one 

 hand, and the Thrushes on the other, in- 

 cluding the starling, the cow-bird, &c. 

 By several authors they are called stur- 

 nidcc. 



GRADUATION {gradus, a degree). 

 The process of dividing a mathematical 

 or astronomical instrument into degrees, 

 minutes, &c., either by copying a system 

 of divisions jdready existing, or by origi- 

 nal division, depending on the geometri- 

 cal properties of the circle. 



GRADUATOR. A contrivance for 

 accelerating spontaneous evaporation by 

 exposing large surfaces of liquids to a 

 current of air. This process of gradu- 

 ation is sometimes employed in salt 



