Calibre of Moulds.

TABLE III.

Of the Calibre of Moulds from 1 to 57 Pounds Ball.

Pounds.Calibre.Pounds.Calibre.Pounds.Calibre.
11002027139339
21262127540341
31442228241344
41582328442347
51712428843350
61812529244353
71912629645355
82002730046358
92082830447361
102152930748363
112223031049366
122283121450368
132353231751371
142413332052373
152473432353376
162523532654378
172573633055380
182623733356382
192673833657385

By this Table, the weight of the ball being given, the size of the mould may be found after the following manner: suppose it be 18 pounds; opposite to it, in the column of calibres, is 262; then say by the rule of proportion, as 100 is to 19 and a half, so is 262 to a fourth term, viz. 51.09 which is the number of lines of the calibre required; therefore, the Calibre of a Rocket of 18 pounds, will be 52 lines nearly, or 4 inches and 4 lines. The calibre may be also found by multiplying the number answering to the pounds by 19½, and cutting off from the product the two last figures; thus suppose the number be 252, which multiply by 19½, the product 4914 separated by the decimal point will give 49.14, or four inches a line and one-eighth.

Now suppose the calibre to be given in lines, the weight of the ball may be found with equal ease, e. g. if the calibre given be 36 lines, then as 19½ : 100 :: 36 : 184; the nearest number in the table to this is 181, which shews that the weight of the ball will be rather more than six pounds; therefore a Rocket, the calibre of which is 36 lines, is a Rocket of a six pound ball.

Remarks on the foregoing Tables.

REMARKS ON THE FOREGOING TABLES.

Table I gives the dimensions of Rocket moulds when the Rockets are rammed solid; it was calculated, as its Author informs us, from repeated experiments; we insert it for the information of our readers, but we would advise none to practise the method of solid ramming.