As pilot well expert in perilous wave

That to a steadfast star his course hath bent,
When foggy mists or cloudy tempests have
The faithful light of that fair lamp yblent,
And covered heaven with hideous dreriment;
Upon his card and compas firms his eye,

The maysters of his long experiment,
And to them does the steddy helm apply,
Bidding his winged vessel fairly forward fly.

SPENSER, Faerie Queen, b. ii. c. 7.

BOOK VI.

THE MECHANICAL SCIENCES.

HISTORY OF MECHANICS,

INCLUDING

FLUID MECHANICS.

ΚΡΑΤΟΣ ΒΙΑ ΤΕ, σφῶν μὲν ἐντολὴ Διὸς
Ἔχει τέλος δὴ, κ' ουδὲν ἐμποδὼν ἔτι.

ESCHYLUS. Prom. Vinct. 13.

You, Fonce and PowER, have done your destined task ; And nought impedes the work of other hands.

INTRODUCTION.

WE enter now upon a new region of the human mind. In passing from Astronomy to Mechanics we make a transition from the formal to the physical sciences; from time and space to force and matter;-from phenomena to causes. Hitherto we have been concerned only with the paths and orbits, the periods and cycles, the angles and distances, of the objects to which our sciences applied; namely, the heavenly bodies. How these motions are produced; -by what agencies, impulses, powers, they are determined to be what they are;-of what nature are the objects themselves;-are speculations which we have hitherto not dwelt upon. The history of such speculations now comes before us; but, in the first place, we must consider the history of speculations concerning motion in general, terrestrial as well as celestial. We must first attend to Mechanics, and afterwards return to Physical Astronomy.

In the same way in which the developement of pure mathematics, which began with the Greeks, was a necessary condition of the progress of formal astronomy, the creation of the science of mechanics now became necessary to the formation and progress of physical astronomy. Geometry and mechanics