200

EXPERIMENTS WITH

TRACT 36.

Here, the numbers in the 6th column, in thousandth partsof an ounce, are equal to the resistance of the plane, placedat the angle on the same line in the first column, whenmaking one revolution, or describing the space 28-f feet, inthe time or number of seconds in the 2nd column, or whenmoving at the rate denoted by the numbers in the 7th co-lumn.

From what has been done, in the last two days, it appears,that there is no sensible difference between the two differentways of putting on the plane, viz, the length or breadth indirection of the length of the arm ; provided its centre bebut at the same distance from the axis, in both cases.

But now to obtain the law of resistance, for the severalangles of inclination, with one and the same velocity, it wasproper to institute a fresh set of experiments, as they herefollow. '

July 31, 1788.

Barometer 29'91; Thermometer 72.

51. The object of this day’s experiments was, to find theresistance on the same plane, at,every angle of elevation,when the velocity, as for example, is 20 feet per second. Itherefore began as follows, putting on different weights, tobring the velocity to about 20 feet in a second.