BOM 



BOM 



SHELLS.— Their Dhnenfiom, Weight, is'c 



Mr. MuUer gives the fo'lowing proportions, from the 1 3 

 inch bombs, now commonly ufed, and obferves that they 

 may be eafily adjulled to any other calibre, by making the 

 diameter of the iliell to 30, as any part exprefied in inches, 

 to the fame part exprelfed in parts of the diameter divided 

 into 30 equal parts. 



Diameter of the bore 



Diameter of the (hell ... 



Diameter of the hollow fphere 



Thicknefs of the metal at the fufce hole 



Thicknefs at the oppofite part 



Diameter of the fulee-hole 



Weight of the Ihell unloaded, 



Weight of the powder contained in the Piiell 



236.5 



N.B. The letter d denotes the cube of the diameter of 

 the bore. 



But (hells have alfo been lately made with the metal 

 «very where of the fame thicknefs, and are found to 

 burft into a greater number of pieces by this condrudlion. 

 The Germans do not name their (hells from the diameter of 

 the bore which receives tlicm, but from the weight of a 

 ftone-ball that fits the fame bore as the (hell. Thus a jlb. 

 howitzer admits a ftone-ball of that weight: the (hell for 

 this weighs i5lbs. and cnrrefponds to the Englifh 5-^ inch. 

 The 3olbs. howitzer (hell weiphs 6o!bs., and is rather more 

 than 8 inches in diameter. At the fiege of Gibraltar, fmall 

 ihells, as \\ inches, and hand-ccranades, were quilted into 

 crape for 13-inch mortars. The fiifees were turned in. 

 wards next the iron-tampion, and leaders of quick-match 

 for communicating fire to the fufees were introduced 

 through holes made in the wond-bottoni, and placed as 

 near the fufees as poffible in tlie centre of the grape. 

 Thefe anfwercd very well for fnort ranges. In general, 

 the winlage, or difference between the diameter of the 

 (hell and mortar, is -irfi^ of the latter ; and the diameter of 

 the hollow part of the (hell is -,'eths of the fame. For finding 

 the wcioht of an iron-fhell, the following rule has been 

 given. Take ^ of the difference of the cubes of the ex- 

 Vernal aisd internal diameters, and this will be its weight , 



In order to find how much powder will fill a (hell ; divide 

 the cube of the internal diameter of the (licU in inches by 

 57.3, which will be the number of pounds of powder. To 

 find the fize of a (hell for containing a given weight of pow- 

 der; multiply the number of pounds of powder by 57.3, and 

 the cube root of the produdl will be the diameter in inches. 



Bombs only differ from granades, in that the latter are 

 much lefs ; and inftead of mortars are thrown out of the 

 hand. Bombs are thrown not only out of mortars and 

 howitzers, but out of cannon. The following (liells may 

 be fired from guns ; viz. hand-granades from 6-pounders ; 

 4y flitUs from i2-pounders ; 5!- (liells from 24-pour.ders } 

 and 8-inch (hells from 68-pr-carronade3. Shells may be 

 alfo thrown from guns to fiiort diftances, in cafe of neceffity, 

 though the bore be not of a diameter fufficient to admit the 

 flieil. For this purpofe the gun may be elevated to any 

 degree that will retain the (hell upon its muzzle, which may 

 be alTified by a fmall line pafTing from the lugs of the (hell- 

 round the neck of the gun. To produce a greater effeft, 

 the fpace between the (hell and the charge may be filled, 

 with wads, or fome other fubifance. 



Bombs may be ufed without mortar- pieces, in the manner 

 praclifed by the Venetians at Candia, when the Turks had 

 poffeffed themfelves of the ditch, roiling down bombs upon 

 them, along a plank fet doping towards their works, with. 

 ledges on the fides to keep the bomb right forwards. They 

 are fometimes alfo buried under ground to blow up. See 

 Caisson'. 



M. Blondel, whohas written on the artof throwing bombs, 

 obferves that the firft bombs were thofe thrown into the 

 city of Watchtendonch, in Guelderland, in 1588, though, 

 others pretend they were in ufe a century before, viz. at 

 the fiege of Naples by Charles VIII. in 1495. Stowe 

 fays (p. 584), that mortars and bombs were invented in 1544» 

 by foreigners, whom Heni-y VIII. employed. But they. 

 came not into common ufe before the year 1634, and then 

 only in the Dutch and Spiinifh armies. One Malthus, an 

 Englilh engineer, is faid to have firft earned them into 

 France, where they were put in ufe at the fiege of Collioure,. 

 in 1642. 



The art of throwing bombs makes a branch of gunnery, 

 founded on the theory of projeflilcs, and the laws and quan-, 

 tities of gun-powder, 



Mefl-.. 



