Transactions, Τόμος 3

Εξώφυλλο
1842
 

Άλλες εκδόσεις - Προβολή όλων

Συχνά εμφανιζόμενοι όροι και φράσεις

Δημοφιλή αποσπάσματα

Σελίδα 350 - It was observed, that the character of the motion of the platform was not that of simple undulation, as had been anticipated, but the movement of the undulatory wave was oblique, both with respect to the lines of the bearers, and to the general direction of the bridge. It appeared that when the summit of the wave was at a given point on the windward side, it was not collateral with it on the leeward side, but, in relation to the flow of the wave, considerably behind it, and forming a diagonal line...
Σελίδα 418 - In framing a theory which shall render a rational account of any natural phenomenon, we have first to consider the agents on which it depends, or the causes to which we regard it as ultimately referable. These agents are not to be arbitrarily assumed; they must be such as we have good inductive grounds to believe do exist in nature...
Σελίδα 418 - ... independently, by direct induction, from experiments purposely instituted; or at least make such suppositions respecting them as shall not be contrary to our experience, and which will remain to be verified by the coincidence of the conclusions we shall deduce from them, with facts. For example, in the theory of gravitation, we suppose an agent— viz. force, or mechanical power— to act on any material body which is placed in the presence of any other, and to urge the two mutually towards each...
Σελίδα 423 - The surest and best characteristic of a wellfounded and extensive induction ... is when verifications of it spring up, as it were, spontaneously, into notice, from quarters where they might be least expected, or even among instances of that very kind which were at first considered hostile to them. Evidence of this kind is irresistible, and compels assent with a weight which scarcely any other possesses.
Σελίδα 353 - ... upon the pyramids, and all the principal parts of the bridge, were as perfect as when first constructed ; it was, however, recommended that " a greater degree of rigidity should be given to the roadways, so that they should not bend so easily under vertical pressure." The bridge remained in the same state until the hurricane of the 6th and 7th of January, 1839; during the night of the 6th, all approach to the bridge was impracticable ; the bridge-keeper, however, ascertained that the roadways...
Σελίδα 159 - ... as 200 Ibs. of coke. The peat coke would, weight for weight, occupy the same, very nearly, as common coke. CALORIFIC POWER. — The next point of investigation was the calorific power, as compared to coal, common coke, and charcoal. The usual method of making assays of this kind, is to burn weighed quantities of the respective fuels, and endeavour to ascertain how much water each respectively will raise a given number of degrees, or convert into vapour. But experiments of this sort, unless made...
Σελίδα 101 - ... feet a mile have practically but little disadvantage compared with a dead level, and that curves may be safely made with radii less than a mile; but that further experiments must be made to determine a safe minor limit for the radii of such curves, this principle being understood to be limited in its application to railways intended chiefly for rapid traffic.
Σελίδα 159 - ... these fuels. It is assumed, from the results of almost all experiments, that the absolute quantity of heat generated, during the combustion of any fuel, is in exact relation to the quantity of oxygen consumed on entering into combination : hence, in order to ascertain the relative calorific powers of fuels, it is only necessary to ascertain the quantity of oxygen each consumes in burning. The best mode of doing this, is to mix a weighed quantity of the fuel with a slight excess of litharge (oxide...
Σελίδα 351 - ... combined with the shrinking of the timber, had relaxed the stiffness of the platform, and permitted an increased degree of undulation. The gate-keeper described the extreme amount of rise and fall of the roadway in a heavy gale to be not less than sixteen feet ; the greatest amount of motion being about half way between the pyramids and the centre of the bridge. In consequence of the injuries sustained during this gale, the author and Mr. Rhodes were instructed to give in a report upon the state...
Σελίδα 418 - ... neutralizes force is force. And again, a plumb-line, which, when allowed to hang freely, always hangs perpendicularly ; is found to hang observably aside from the perpendicular when in the neighbourhood of a considerable mountain ; thereby proving that a force is exerted upon it, which draws it towards the mountain. Moreover, since it is a fact that the moon does circulate about the earth, it must be drawn towards the earth by a force ; for if there were no force acting upon it, it would go on...

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