Youth's Book of Natural Philosophy

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Reed and Barber, 1838 - 258 Seiten
 

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Seite 71 - ... 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...
Seite 253 - Tutor. (1.) A magnet attracts iron. (2.) When placed so as to be at liberty to move in any direction, its north end points to the north pole, and its south end to the south pole : that is called the polarity of the magnet.
Seite 72 - Now if this wheel has sixty teeth, as is common, it will just turn round once for sixty beats of the pendulum, or seconds, and a hand fixed on its axis projecting through the dial-plate, will be the second hand of the clock. The other wheels are so connected with the first, and the numbers of...
Seite 245 - But independent of the great fimilarity between the effects of lightning and thofe of electricity, what fully proves their identity, is, that the matter of lightning may be actually brought down from the clouds by means of infulated metallic rods, or of electrical kites, and with it any known electrical experiment may be performed.
Seite 58 - The actions and postures of animals, and particularly of man, illustrate beautifully the observations made above with respect to the centre of gravity. A body, we have seen, is tottering in proportion as it has great altitude .and narrow base — but it is the noble prerogative of man to be able to support his towering figure with great firmness, on a very narrow base, and under constant change of attitude.
Seite 209 - ... either side, the hand of the image will move towards the other ; so that whatever way the object moves, the image will move the contrary way.
Seite 60 - ... them steady. The habit of using the stilts is acquired early, and it appeared that the smaller the boy was, the longer it was necessary to have his stilts. By means of these odd additions to the natural leg, the feet are kept out of the water, which lies deep during winter on the sands, and from the heated sand during the summer: in addition to which, the sphere of vision over so perfect a flat is materially increased by the elevation, and the shepherd can see his sheep much farther on stilts...
Seite 66 - ... feet per second. Great charges of powder are, therefore, not only useless, but dangerous; for, though they give little additional force to the ball, they hazard the lives of many by their liability to burst the gun.
Seite 206 - One who looks into a concave mirror sees his own face varied in the following manner. When he holds the reflector near to his face, he sees his image distinct, because the rays come to the eye diverging (which is their natural state with respect to near objects,) and enlarged, because, as the rays diverge less than before, the image is thrown back to a greater distance behind the mirror than the object is before it, and the magnitude is as that distance by article 875.
Seite 256 - ... exude, it simply combines with the solution, making a mass much like red wax. I lay on the solution also for a little distance beyond the wound, and wait a few moments to allow for the evaporation of ether. Next I take from the wineglass the saturated cotton-wool with forceps, and lay a seam of it, half an inch wide and the eighth of an inch in thickness, over the line of incision. Finally, I coat the whole over with another layer of the solution, wait until the layer is nearly dry, cover with...

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