Popular Lectures on Science and Art: Delivered in the Principal Cities and Towns of the United States, Volum 1

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Greeley & McElrath, 1846
 

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Passatges populars

Pàgina 121 - I say, if these things are so, may not the knowledge of this power of points be of use to mankind, in preserving houses, churches, ships, &c., from the stroke of lightning, by directing us to fix, on the highest parts of those edifices, upright rods of iron made sharp as a needle, and gilt to prevent rusting, and from the foot of those rods a wire down the outside of the building into the ground, or down round one of the shrouds of a ship, and down her side till it reaches the water?
Pàgina 121 - If any danger to the man should be apprehended (though I think there would be none), let him stand on the floor of his box, and now and then bring near to the rod the loop of a wire that has one end fastened to the leads, he holding it by a wax handle ; so the sparks, if the rod is electrified, will strike from the rod to the wire, and not affect him.
Pàgina 121 - To determine the question, whether the clouds that contain lightning are electrified or not, I would propose an experiment to be tried where it may be done conveniently.
Pàgina 25 - The square of the hypotenuse of a right-angled triangle is equal to the sum of the squares of the other two sides.
Pàgina 122 - With this apparatus, on the appearance of a thunder-gust approaching, he went out into the commons, accompanied by his son," to whom alone he communicated his intentions, well knowing the ridicule which, too generally for the interest of science, awaits unsuccessful experiments in philosophy.
Pàgina 248 - Saturn, yet micrometrical measurements of extreme delicacy" have demonstrated that the coincidence is not mathematically exact, but that the centre of gravity of the rings oscillates round that of the body, describing a very minute orbit, probably under laws of much complexity.
Pàgina 114 - Electricity, which was more generally read and admired in all parts of Europe than these letters. There is hardly any European language into which they have not been translated...
Pàgina 121 - ... feet, pointed very sharp at the end. If the electrical stand be kept clean and dry, a man standing on it, when such clouds are passing low, might be electrified and afford sparks, the rod drawing fire to him from a cloud.
Pàgina 171 - ... domain of physical science, and clothes the natural philosopher with powers denied to the political and moral inquirer, yet foreknowledge is eminently the privilege of the astronomer. Nature has raised the curtain of futurity, and displayed before him the succession of her decrees, so far as they...

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