298

THEORY AND PRACTICE

TRACT 37 '

172. There is another circumstance, which occasions thespace, at first occupied t>v the inflamed powder, to be largerthan that at which it has been taken, in the foregoing calcu-lations; and that is the difference between the content of asphere and cylinder. For, the space supposed to be occu-pied at first by the elastic fluid, was considered as the lengthof a cylinder measured to the hinder part of the curve sur-face of the hall, which is manifestly too little, by the differ-ence between the content of half the ball, and a cylinder ofthe same length and diameter, that is, by a cylinder whoselength is A of the semidiameter of the ball. Mow that dia-meter was 1‘96 inches ; the half of which is 0‘98, and d- of thisis nearly 0'33. Hence then it appears that the length of thecylinders, at first supposed to be filled by the dense fluid,viz, 3'45, and 5'99, and 11 -07, have been all taken too littleby 0'33; and hence it follows that, on this account also, alltire numbers before, found for the value of the first, force n,must be further increased in the ratios of 3*45 and 5 - 99 andn - 07, to the same numbers increased by 0-33, that is, to thenumbers 3-73 and 6 32 and 11-40. When this is done, thenumbers for the value of n, so increased, will be as in the.annexed tablet.

Powder.

The Guns.

OA

2

3

4

4

1359

1376

1427

1421

3

1457

1612

1793

1840

16

1660

1654

1SI 1

1826

173. Another source of diminution of the force, is thewaste of the fluid by the vent and the windage. These di-minutions, from the extreme rapidity of the fluid, must bevery considerable, though the effects are very difficult to becomputed with accuracy. This loss of force arises fromhence, that while the hall passes along the gun cylinder, theelastic fluid constantly escapes, not only at the vent or touch-hole, but also between the ball and the sidesof the cylinder;so that the elastic force must always be greater than those