Proceedings of the American Association for the Advancement of Science, Volumen 9

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Página xv - The objects of the Association are, by periodical and migratory meetings, to promote intercourse between those who are cultivating science In different parts of America, to give a stronger and more general impulse and more systematic direction to scientific research, and to procure for the labors of scientific men increased facilities and a wider usefulness.
Página 42 - Each candidate is to send his exercise privately: each is to have some motto prefixed; and to be accompanied by a paper sealed up, with the same motto on the outside; which paper is to enclose another, folded up, having the candidate's name and college written within. The papers containing the names of those persons who do not succeed are destroyed unopened.
Página 79 - This interesting fact was verified in a series of experiments embracing samples of nearly all the marbles under trial, and in no case did a single exception occur to vary the result. " The explanation of this remarkable phenomenon (now that the fact is known) is not difficult.
Página 41 - PRIZE," be awarded every two years to the author of the best Essay on some subject of Pure Mathematics, Astronomy, or other branch of Natural Philosophy. 2. That the...
Página 185 - ... least. Whenever a garnet or a lump of quartz was imbedded in compact feldspar, and favorably presented to the action of the sand, the feldspar was cut away around the hard mineral, which was thus left standing in relief above the general surface.
Página 79 - ... of least resistance, and the remaining pressure must be sustained by the central portions around the vertical axis of the cube. After this important fact was clearly determined, lead and all other interposed substances were discarded, and a method devised by which the upper and lower surfaces of the cube could be ground into perfect parellelism.
Página 75 - Though the art of building has been practised from the earliest times, and constant demands have been made, in every age, for the means of determining the best materials, yet the process of ascertaining the strength and durability of stone appears to have received but little definite scientific attention, and the commission, who...
Página xxvii - Silurian, for much of the lowest granite cannot be excluded. no fossils ; and moreover, the beds on this continent were uplifted and folded, and, to a great extent, crystallized, on a vast scale, before the first Silurian layers were deposited. A grand revolution is here indicated, apparently the closing event of the early physical history of the globe. As plants may live in water too hot or impure for animals, and moreover, since all nature exemplifies the principle that the earth's surface was...
Página 174 - ... abundant with some galena and carbonate; a little lower down the phosphate was less, and the carbonate more abundant. Wulfenite and anglesite began to appear at 120 feet, the phosphate and carbonate still continued with the galena, with fine large crystals of anglesite and considerable wulfenite : at 180 feet, phosphate very much diminished, carbonate and sulphate in fine crystals ; arsenate was found here ; at 240 feet, blende, calamine and fluor spar appear with considerable dolomite and but...
Página 84 - Another effect of the lateral motion of the atoms of a soft heavy body, when acted upon by a percussive force with a hammer of small dimensions in comparison with the mass of metal, — for example, if a large shaft of iron be hammered with an ordinary sledge, — is a tendency to expand the surface so as to make it separate from the middle portions. The interior of the mass by its own inertia becomes as it were an anvil, between which and the hammer the exterior portions are stretched longitudinally...

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