TRACT 36.

THE WHIRLING-MACHINE.

197

EXPERIMENTS IN 1788 WITH THE WHIRLING-MACHINE.

July 23, 1788.

46. Prepared the machine to make experiments withfigures of shapes different from the foregoing ones. Pro-viding a thin rectangular plate of brass, to fix on the armof the machine; its weight 11 oz 0|- dr, or ll^V oz, and itsdimensions 8 inches by 4, consequently its area was 32square inches, the same as the plane surface of the cone andlarge hemisphere, before employed. It was adapted for fit-ting on the end of the arm in both directions, viz, in the di-rection both of the length and of the breadth, to try the ef-fect of the same surface in both positions. It was also con-trived to incline the surface in any degree to the directionof motion, to try the resistance at all angles of inclination.When fitted on with its length in the direction of the arm,the distance of its centre, from the axis of motion, -was 531-inches ; and the same distance also when fitted on the otherway.

July 24, 1788.

Barometer 30'0 ; Thermometer 70|.

47. Tried the experiments this day with the plane fittedon with its length in the direction of the arm, its centre be-ing distant 53 J inches from the axis of motion. The planewas inclined in various angles, as expressed below; and theactuating weight was 32 oz or 2lb each time.

Table of the Times of Revolution, the Plane lengthwise.

0° orhori-zontal

5°

10°

O

o

30°

o

O

45°

50° j 60°

' O

O

00

o

o

90°or ver-tical

POO"

P17"

P34"

P67"

GO

2-lT

2-40"

2'54" 2-78"

2-94"

5-00"

3'02"

In the first line of this table, are the angles in which theplane was inclined to tlie horizon, or to its path, sometimesat 5 degrees, and sometimes at 10 °, difference from each