_GIN Triangle._—Length of arms of the gin 16 feet 4½ inches. Roller, 6 feet long. Tackle fall, 78 feet of 3 inch white rope. Sling, 6 inch white rope. For the different exercises of the gin, see the word _Exercise_. _GRAVITY.—Table of the Specific Gravity of several Solid and Fluid Bodies._ Platina 23400 Nitre 1900 Fine gold 19640 Ivory 1825 Standard gold 18888 Brimstone 1810 Quicksilver 11325 Solid gunpowder 1745 Fine silver 11091 Sand 1520 Standard silver 10535 Coal 1250 Copper 9000 Boxwood 1030 Copper halfpence 8915 Sea water 1030 Gun metal 8784 Common water 1000 Cast brass 8000 Oak 925 Steel 7850 Gunpowder, close stacken 937 Iron 7645 ” in loose heap 836 Cast iron 7425 Ash 800 Tin 7320 Maple 755 Crystal glass 3150 Elm 600 Marble 2700 Fir 550 Common green glass 2600 Charcoal Flint 2570 Cork 240 Common stone 2520 Air 1.232 Clay 2160 Brick 2000 Common earth 1984 The several sorts of wood are supposed dry. This table also contains the weight of a cubic foot of each body in avoirdupois ounces; from whence results the following rules: 1. _To find the Magnitude of any Body from its Weight._ As the tabular specific gravity of the body Is to its weight in avoirdupois ounces, So is one cubic foot, or 1728 cubic inches, To its content in feet or inches respectively. 2. _To find the Weight of a Body from its Magnitude._ As one cubic foot, or 1728 cubic inches, Is to the content of the body, So is the tabular specific gravity To the weight of the body. _GRAPE SHOT._—See the word _Shot_. _GRANADES._—Hand granades may be thrown to the distance of 13 fathoms. For their dimensions, see the word _Shell_. _GUNNERY._—By the assistance of good tables of practice, and the tables of amplitudes, sines, tangents, and secants, all the cases in gunnery in a nonresisting medium may be easily solved; and perhaps the solution may be sufficiently correct for practice, if the initial velocity of the projectile be not so great as to make the air’s resistance considerable. For the tables of ranges with ordnance, see the different natures, as _Gun_, _Mortar_, &c. and for the tables of amplitudes, sines, tangents, and secants, see pages 151 and 152.