Boston School Compendium of Natural and Experimental Philosophy

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Thomas H. Webb & Company, 1844 - 237 pages

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Page 176 - Mars a rather large pin's head, on a circle of 654 feet; Juno, Ceres, Vesta, and Pallas, grains of sand, in orbits of from...
Page 34 - ... to counteract the retarding effects of friction and the resistance of the air. The wheels show how many swings or beats of the pendulum have taken place, because at every beat, a tooth of the last wheel is allowed to pass. Now, if this wheel...
Page 109 - ... the angle of reflection is always equal to the angle of incidence, the image for any point can be seen only in the reflected ray prolonged.
Page 41 - ... that the axle describes a small one ; therefore the power is increased in the same proportion as the circumference of the wheel is greater than that of the axle. If the velocity of the wheel be...
Page 122 - ... common heat of the sun as the area of the glass is to the area of the focus. Thus, if a lens, four inches in diameter, collect the sun's rays into a focus at the distance of twelve inches, the image will not be more than one-tenth of an inch in diameter ; the surface of this little circle is 1600 times less than the surface of the lens, and consequently the heat will be 1600 times greater at the focus than at the lens.
Page 3 - If some water be put into a tube closed at one end, and a piece of wood be inserted that fits the inside of the tube very accurately, it will be impossible by any force to get the wooden piston to the bottom of the tube, unless the water is taken away.
Page 176 - Venus a pea, on a circle of 284 feet in diameter ; the Earth also a pea, on a circle of 430 feet ; Mars a rather large pin's head, on a circle of 654 feet ; the Asteroids, grains of sand, in orbits of from 1000 to 1200 feet; Jupiter a moderate-sized orange, in a circle nearly half a mile across...
Page 88 - Soond, like light, after it has been reflected from several places, may be collected into one point, as a focus, where it will be more audible than in any other part ; and on this principle whispering galleries may be constructed.
Page 121 - In order to estimate the effect of a lens, we must consider the situation of the perpendicular, with respect to the surface of the lens. Now, a perpendicular, to any convex or concave surface, must always...
Page 119 - Let a piece of money be put into a cup or a bowl, and the cup and the eye be placed in such a position that the side, of the cup will just hide the money from the sight; then, keeping the eye directed to the same spot, let the cup be filled with water,— the money will become distinctly visible.

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