A System of Mechanical Philosophy, Volume 1 |
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ABFD abutment accelerating force action angle arch atoms attraction axis ball beam body carpentry centre of gravity change of motion circle cohesion compression consider corpuscular forces curvature curve deflection described diagonal diameter direction distance dome draw elastic employed equal equi equilibrio exerted experiments external force feet fibres fracture frame glass gonal greater hesion horizontal inch instant inversely James Bernoulli joints joist king-post length lever load manner measure mechanical mechanical philosophy mortise mortise and tenon moving force mutual observed ordinates parallel parallelogram particles perpendicular phenomena piece plane plates polygon pressure principles produced proportion proposition purlins radius rafters ratio repulsion resistance rest rhombus roof round shew side solid space square stone strain strength STRENGTH OF MATERIALS struts suppose surface thrust tie-beam timber tion transverse triangle truss uniformly velocity vertical weight whole
Popular passages
Page xi - Newcomen's engine, with a wooden cylinder six inches diameter, and twelve inches long in the stroke. 6th, I had measured the quantity of cold water required in every stroke to condense the steam in that cylinder, so as to give it a working power of about 7 lb.
Page 395 - According to Mr. Emerson, the load which may be safely suspended to an inch square, is as follows : Iron 76,400 Brass 35,600 Hempen rope ... 19,600 Ivory 15,700 Oak, box, yew, plumtree 7,850 Elm, ash, beech - - - 6,070 Walnut, plum - - - - 5,360 Red fir, holly, elder, plane, crab - - - - 5,000 Cherry, hazel • - - - 4,760 Alder, asp, birch, willow 4,290 Lead...
Page 597 - Two models were made 18 inches ^square ; one consisted of .single joists, the other framed with girders, binding, bridging, and ceiling joists; the single joists of the one contained the same quantity of timber with the girders alone of the other. They were placed in a wooden trunk 18 inches square within, with a strong projection on the inside for the floors to rest on, and small shot was gradually poured over. The single joisted floor broke down with 487 pounds ; the framed floor, with 32 7 pounds.
Page 524 - No. 1 and 2. If considered merely as two pieces of wood joined, it is plain that, as a tie, it has but half the strength of an entire piece, supposing that the bolts (which are the only connections) are fast in their holes. No. 2 requires a bolt in the middle of the scarf, to give it that strength ; and, in every other part, is weaker on one side or the other. But the bolts are very apt to bend by the violent strain, and require to be strengthened by uniting their ends by iron plates ; in which case...
Page 524 - This form, without a key, needs no bolts (although they strengthen it greatly) ; but, if worked very true and close, and with square abutments, will hold together, and will resist bending in any direction. But the key is an ingenious and a very great improvement, and will force the parts together with perfect tightness. The same precaution must be observed that we mentioned on another occasion, not to produce a constant internal strain on the parts by overdriving the key. The form of fig.
Page 566 - ... the point where the directions of the supports intersect each other. If the centre of gravity rises by this motion, the body will have a tendency to recover its former position, and it will require force to keep it away from it. In this case the equilibrium may be said to be stable, or the body to have stability. But if the centre of gravity descends when the body is moved from the position of equilibrium, it will tend to move still farther ; and so far will it be from recovering its former position,...
Page 590 - In this case, the rafter acts as a powerful lever, whose fulcrum is the inner angle of the shoulder, and then the strap never fails to cripple the rafter at the point. All this can be prevented only by making the strap very long and very oblique, and by making its outer end (the stirrup part) square with its length, and making a notch in the rafter foot to receive it. It cannot now cripple the rafter, for it will rise along with it, turning round the bolt at its inner end. We have been thus particular...
Page xi - I afterwards made in the engine. These improvements proceeded upon the old-established fact, that steam was condensed by the contact of cold bodies, and the later known one, that water boiled in vacuo at heats below 100", and consequently that a vacuum could not be obtained unless the cylinder and its contents were cooled every stroke to below that heat.
Page xi - Although Dr Black's theory of latent heat did not suggest my improvements on the steam-engine, yet the knowledge upon various subjects which he was pleased to communicate to me, and the correct modes of reasoning, and of making experiments of which he set me the example, certainly conduced very much to facilitate the progress of my inventions...
Page 600 - When carried so much higher that the distance of the ribs is one third of the original distance, every second rib, now consisting of two ribs very near each other, is in like manner discontinued, and the void is glazed. A little above this the heads of the ribs are framed into a circular ring of timber, which forms a wide opening in the middle ; over which is a glazed canopy or umbrella, with an opening between it and the dome for allowing the heated air to get out. All who have seen this dome say...