A System of Natural Philosophy: Designed for the Use of Schools and Academies, on the Basis of The Book of Science by J.M. Moffat ... with Emendations, Notes, Questions for Examination, Lists of Works for Reference, Some Additional Illustrations, and an IndexE.C. Biddle, 1842 - 473 من الصفحات |
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action angle appear applied ascertained atmosphere attraction axle ball cause centre of gravity centrifugal force circumstances colours common concave consequence construction convex convex lens cord cylinder degree density depend descend described diameter direction distance earth effect elastic electricity equal equilibrium estimated exhibited experiments Fahrenheit falling bodies feet fluid friction fulcrum glass glottis heat Hence inches inclined plane instrument kind latter length lens lever light liquid machine magnetic manner mass means mechanical mercury metal mirror motion moving body Natural Philosophy object observed oscillation parallelogram of forces passing peculiar pendulum phenomena philosophers piston plate pole pounds pressure principle produced properties proportion pulley purpose rays reflected refraction relative resistance retina screw side simple machines solid sound space specific gravity square substances Suppose surface takes place temperature thermometer tion tube valve velocity vertical vessel vibrations voltaic pile weight wheel wire
مقاطع مشهورة
الصفحة 28 - Every body continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it.
الصفحة 63 - The time of one' vibration is to the time of the descent, through half the length of the pendulum, as the circumference of a circle to its diameter.
الصفحة 427 - Electricity is usually developed, in order to show its effects, by the friction of glass. The earlier electricians, in the prosecution of their researches, merely used glass tubes or other nonconductors, held in one hand and rubbed with silk or flannel.
الصفحة 452 - It consists of a bar of soft iron, bent into the form of a horse-shoe, and wound with twenty-six strands of copper bell-wire, covered with cotton threads, each thirtyone feet long; about eighteen inches of the ends are left projecting, so that only twenty-eight feet of each actually surround the iron. The aggregate length of the coils is therefore 728 feet. Each strand...
الصفحة 235 - ... perceives them may be said to possess another sense, agreeing with our own solely in the medium by which it is excited, and possibly wholly unaffected by those slower vibrations of which we are sensible."* 21.
الصفحة 156 - The method of communicating buoyancy to solids of greater specific gravity than water, and enabling them to float in that fluid, by inclosing within them air or gas, is susceptible of application to a variety of useful purposes. It has accordingly been adopted in the construction of swimming-girdles, life-preserving belts, and air-jackets, which like the bladders noticed above, are merely bags of different shapes contrived so as to be inflated with air, and worn round the upper part of the body....
الصفحة 204 - What two different arrangements of parts are occasionally applied for retaining the condensed air r earth, sustain a pressure from the superincumbent atmosphere equal to the weight of a column of water, about 34 feet in height, with a base corresponding in extent to that of the body or bodies pressed upon. This pressure may be estimated at from 14 to 15 pounds on every square inch of surface, being the weight of a column of mercury 30 inches high, and 1 inch square at the base.
الصفحة 175 - Montgolfier, distinguished for his share in in the invention of the air-balloon. The hydraulic ram operates chiefly from the momentum of a current of water, suddenly stopped in its course, and made to act in another direction ; and as it produces a kind of intermitting motion, owing to the alternate retreat and access of the stream, accompanied with a noise arising from the shock, its action has been compared to the butting of rams ; and hence the name of the machine.
الصفحة 367 - CG, passing through the centre of the lens, do not alter their direction. C G' is termed the "focal distance" of the lens; and in a double convex lens, formed of equal spherical surfaces, its length will be that of the radius of the sphere of which those surfaces form portions. In...