TRACT 34.

IN GUNNERY.

357

= 1706 for the velocity by that method. But the meanvelocity by the pendulum is 2030, which exceeds theformer by 324, or almost -£• of the whole velocity.

49. Thursday, July 17, 1783 ; from 12 till 3 P.M.Fine, clear, hot weather.

Barometer 30 23, Thermometer 72° at 9 o’clock'.

gun n* 1.

Weight - - - - 917

To centre of gravity 80'47To the tape - - - 110"2

It swung very freely, andwould have continued its vi-brations a long time; owingto the ends of the axis beingmade to turn or roll upon aconvex iron support, andkept from going backwardand forward, with the vibra-tions, by two upright ironpins, placed so as not quiteto touch the axis, but at avery small or,hair-breadthdistance from it.

PENDULUM.

W eight - - 657

To centre of gravity 77’26To the tape - - - 118

The pendulum would notvibrate longer than 1 minutebefore the arcs became im-perceptible, owing to thefriction of the upright pins,which touchedand bore hardagainst the sides of the axis,unlike those of the gun,though they had the samekind of round support torollon. The pendulum hadbeen well repaired, andstrengthened with iron bars,and straps going round itin several places, exceptover the face. Also thickf iron plates were let into,and across it, near the backpart, then over them waslaid a firm covering of rope,after which the rest of thehole was filled up with ablock of elm, and finallythe face covered ovgr with,sheet lead.