Tbact 37.

OF GUNNERY.

259

99. Corollary. In the same manner hasbeen computed the annexed table of theinitial velocities, of any cast iron balls, asprojected from the usual length of guns,by all the charges of powder, from ^ theweight of the shot, up to the full weightof the same ; the strength of the powderbeing supposed uniform, and of the bestkind used by government, or such as willshow 40 or upwards, on the line of chordsof my powder eprouvette, by the explo-sion of 2 ounces of the powder.

The first column of the table show's howoften the wt. or charge of powder c, iscontained in the weight of the ball b, beingthe quotient of the ball divided by thecharge of powder, or the ratio of the for-mer to the latter. And the latter columncontains the correspondentvelocitiesgivento the ball by those charges, being the

several values of the theorem IGOOy— in

0

feet.

Propor-tion ofhall topowder,b

viz. — —c

Veloc.of ballin fept, <viz,

2c

1600VX

20

506

19

519

18

533

17

549

16

566

15

5 84

14

605

13

628

12

653

11

682

10 .

716

9

755

8

800

7

855

6

924

5

1012

4

1131

3

1306

2

1600

1

2263

100. This table will be useful on many occasions, thevelocity being taken out by inspection : So, if it be desiredto know what velocity will be given to a ball by ^ of itsweight of powder, the table shows between 1100 and 1200feet. Or, reversewise, it show's what proportion of chargewill give the ball any proposed velocity. For numbersintermediate to those in the table, proportion or an allow-ance may be made ; so, if it be desired to know what chargewill give any ball a velocity of 1500 feet per second, the ta-ble shows that the requisite charge of powder must be nearlya medium between \ and -J- the weight of the ball. But ifthe exact quantity of charge be desired, it will be easily ob-tained by using the general theorem leoOy'y, viz, in the