ON RAIL-ROADS.

197

Having thus ascertained the friction relativeto the weight, the following experiments weremade with the dynamometer, to ascertain thefriction or resistance of carriages moving atdifferent velocities.

EXPERIMENT XI.

No

DESCRIPTION OF CARRIAGES, AND VELOCITIES AT WHICHTHEY MOVED.

Resistance 1

in lbs, [

leaded carriage, weighing 22 J cwt. with cast-ironbearings, four inches broad, case-hardened wheelsthirty-four inches diameter, and wrought-iron axles twoand three quarter inches diameter, containing 53 cwt.of coals, moved at a slow rate of motion

56

2

Moved at the rate of 134 feet in a minute

56

3

Ditto 307 Ditto

56

4

Ditto 397 Ditto

56

5

Ditto 140 Ditto

56

In prosecuting the above experiments, thecarriage and dynamometer were first put intothe required velocity, and that velocity wasuniformly kept up during their passage alongthe plane. Numerous trials were made, to becertain that the result was correct; the dynamo-meter was pushed along by several men, andthe variation from a uniform resistance, indi-cated by the index, was so trifling, that no otherrecord than those in the table could be made.This experiment was made, in conjunctionwith Mr. Stephenson, in 1819.

To determine this question by a method dif-ferent from the preceding, and where, perhaps,