Comentarios de la gente - Escribir un comentario
No encontramos ningún comentario en los lugares habituales.
angles of incidence aperture arms atmosphere axis ball barometer body called cause centre of gravity centrifugal force centripetal force circle circular coloured convex lens cord crystal crystalline lens curve diameter diminished direction distance double refraction earth effect elastic equal fall feet per second fire balloon fluid friction given glass greater Hence inches inclined plane increased index of refraction inversely last acquired velocity latter length lens less lever light mass mercury mirror momentum moon motion movable move multiplied nearly number of revolutions object opposite parallel particles passes pendulum perpendicular pinion pipe piston placed plate polarized portion pressure principal focus principle produced pulley pump quantity radius rays reflected refraction represented resistance revolutions per minute revolve round screw side sound space specific gravity square substance surface teeth tion triangle tube valve vessel vibration weight
Página 295 - School," affords a striking example of the successful manner in which some of the most important truths of Revelation are blended with secular instruction in the Irish National School Books. THIRD BOOK OF LESSONS, 12mo, 288 pages, Price Eight Pence.
Página 274 - It may also be defined as the sine of the angle of incidence divided by the sine of the angle of refraction, as light passes from air into the substance.
Página 54 - Buchanan that the same quantity of human labour employed in working a pump, turning a winch, ringing a bell, and rowing a boat, are as the numbers 100, 167, 227, and 248. The most advantageous manner of applying human strength is in the act of rowing.
Página 224 - ... that the ratio of the sines of the angles of incidence and refraction is constant for refraction in the same medium, was effected by Snell and Descartes.
Página 293 - An inspection of the Irish National School Books will show, that, whilst they are replete with instruction in every branch of literature and science with which it is necessary that the children of all classes should be familiar, the elementary works for reading are penetrated with the spirit of religion and morality. They may be read with safety by the members of every religious persuasion, and with equal advantage by the rich and the poor— by adults as well as by children.
Página 70 - In the wheel and axle, an equilibrium takes pl.ice when the power multiplied by the radius of the wheel, is equal to the weight multiplied by the radius of the axle ; or P : W : : CA : CB.
Página 167 - ... volume of water required to pass a boat up or down is termed the prism of lift. The calculation, therefore, for the quantity of water requisite for the service of the navigation, will be simply that of the number of prisms of lift...
Página 168 - Rule. — Measure the depth from the surface of the water to the centre of the orifice of discharge, in feet, and extract the square root of that depth ; multiply it by...
Página 247 - ... from, the eye, till they seem exactly to cover the small circle viewed through the telescope. The quotient obtained by dividing the distance of the paper circle by the distance of the parallel lines from the eye, will be the magnifying power of the telescope.