Practical Essays on Mill Work and Other Machinery, Volumes 1-2

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J. Taylor, 1823 - Machinery - 588 pages
 

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Page 123 - A circle is a plane figure contained by one line, which is called the circumference, and is such that all straight lines drawn from a certain point within the figure to the circumference, are equal to one another.
Page 124 - A diameter of a circle is a straight line drawn through the centre, and terminated both ways by the circumference.
Page 335 - By this form they become incomparably stronger and stifier, and give more room for the insertion of muscles, while they are lighter and therefore more agile ; and the same wisdom has made use of this hollow for other valuable purposes of the animal economy. In like manner, the quills in the wings of birds acquire by their thinness the very great strength which is necessary, while they are so light as to give sufficient buoyancy to the animal in the rare medium in which it must live and fly about....
Page 372 - All woods are more tenacious while green, and lose very considerably by drying after the trees are felled The only author who has put it in our power to judge of the propriety of his experiments is Muschenbroek. He has described his method of trial minutely, and it seems unexceptionable. The woods were all formed into slips fit for his apparatus, and part of the slip was cut away to a parallelepiped of one fifth of an inch square, and therefore one twenty-fifth of a square inch in section. The absolute...
Page 126 - Parallel straight lines are such as are in the same plane, and which being produced ever so far both ways, do not meet.
Page 203 - ... is driven by a wheel, the number of teeth in the pinion should not be less than eight. When a wheel is driven by a pinion, the number of teeth in the pinion should not be less than ten. The number of teeth in a wheel should...
Page 217 - The arms should become larger as they approach the centre of the wheel, (see Emerson, Prop. 119, Rule 8,) and the eye E, should be sufficiently strong to resist the driving of the wedges, by means of which it is to be fixed on the shaft. This cannot be brought easily to calculation. On the other hand, care must be taken not to make the eye so thick as to endanger unequal cooling. It should be somewhat broader than the breadth of the teeth, in order that it may be the firmer on the shaft: this breadth...
Page 111 - ... circle. It has been supposed by some of the best authors that the epicycloidal tooth has also the advantage of completely avoiding friction ; this is however by no means true, and it is even impracticable to invent any form for the teeth of a wheel, which will enable them to act on other teeth without friction. In order to diminish it as much as possible, the teeth must be as small and as numerous as is consistent with strength and durability ; for the effect of friction always increases with...
Page 140 - A rule, though not absolutely perfect, is better in all cases than to have no guide whatever. "And it is too evident to require proof, that it is essential to the beauty and utility of any machine, that the strength and bulk of its several parts be duly proportioned to the stress, or wear, to which the parts may be subject. "Some general observations on the wheel-work of mills, will serve greatly to simplify our inquiries on the subject.
Page 334 - Here we see the admirable wisdom of the author of nature in forming the bones of animal limbs hollow. The bones of the arms and legs have to perform the office of levers, and are thus opposed to very great transverse strains. By this form they become incomparably stronger and stiffer, and give more room for the insertion of muscles, while they are lighter and therefore more agile ; and the same wisdom has made use of this hollow for other .valuable purposes of the animal economy. In like manner,...

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