heated by an electrical explosion as much as iron. In accordance with this fact, it was found that wires drawn from some foreign gold coins, said to be very pure, were much worse conductors of electricity, than when drawn from the same previously refined.

I did not find the conducting power to be influenced by any new disposition or arrangement of the quantity of metal; thus, whether the metallic wire was perfectly cylindrical, flattened into a ribbon, or separated into four smaller wires, the effect produced was in each case alike.

The influence of a small portion of alloy on the conducting power renders it necessary to have the metals pure, and I have reason to believe that the specimens, which were in these instance's made the subjects of experiment, were as nearly so as possible.

The alloys were prepared by fusing the metals together with a common blow-pipe on a charcoal support, having previously weighed the relative proportions; after which the small button of metal was again weighed and drawn into wire. I am not aware that this method of forming alloys with small quantities of metal is liable to any material error.

The wires operated on in the course of this investigation varied from theth to theth of an inch in diameter, below which it was not found desirable to reduce them.

EXPLANATION OF PLATE II.

abcd The glass bulb.

ab The wire.

d The brass caps and screws which unite the ball to the

glass cup.

e The glass cup.

c A small valve.

ab The flanches and balls.

gfe The glass tube.

gf The scale.

s The stand.

Pa. bN The connecting wires.

III. On the expediency of assigning specific names to all such functions of simple elements as represent definite physical properties; with the suggestion of a new term in mechanics; illustrated by an investigation of the machine moved by recoil,

and also by some observations on the Steam Engine. By DAVIES GILBERT, Esq. M. P. V. P. R. S. &c.

Read January 25, 1827.

THE expediency of distinguishing by separate appellations,

all such functions of simple elements as measure the intensity of physical properties, will be rendered obvious by referring to the well known controversy respecting motion.

Scarcely had the principles which regulate the action of bodies in motion become subjected to mathematical calculation, when a dispute arose as to the measure of motion itself; a dispute conducted with much more vehemence and acrimony than might be supposed incident to the nature of an abstract subject.

Several individuals of the greatest learning and reputation contended that weight, multiplied by velocity, (w xv) gave a product always proportionate to the motion of bodies, as was proved by a comparison of their inertia, by all the properties relative to the common centre of gravity in planetary systems, &c. &c. &c.; while other persons, scarcely inferior to the former, adverting to the collision of elastic bodies, and to the extremely curious property of motion, the conservatio virium vivarum, contended with equal confidence, that the true measure of motion was weight multiplied into