An Introduction to the Theory and Practice of Mechanics: In Five Books ...

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J. Hellaby, 1810 - Mechanics - 455 pages

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Page 264 - ... 2. The load at the maximum is nearly, but somewhat less than, as the square of the velocity of the wind, the shape and position of the sails being the same.
Page 264 - ... when the velocities compared are more than double of that where the given load produces a maximum, the effects increase nearly in a simple ratio of the velocity of the wind.
Page 265 - ... horizontal windmill, little more than one sail can be acting at once : whereas, in the common windmill, all the four act together : and, therefore, supposing each vane of a horizontal windmill, of the same dimensions as each vane of the vertical, it is...
Page 41 - Centre of gravity of any body, or system of bodies, is that point upon which the body or system of bodies...
Page 6 - Every body continues in its state of rest, or uniform motion in a straight line, unless it is compelled to change that state by forces impressed on it (inertia).
Page 264 - ... 7. The load at a maximum that sails of a similar figure and position will overcome, at a given distance from the centre of motion, will be as the cube of the radius.
Page 41 - The centre of gravity of a body is not always within the body itself : thus the centre of gravity of a ring is not in the substance of the ring, but in the axis of its circumscribing cylinder ; and the centre of gravity of a hollow staff, or of a bone, is not in the matter of which it is constituted, but somewhere in its imaginary axis ; every body, however, has a centre of gravity, and so has every system of bodies.
Page 261 - Were nothing more requisite than to cause the sails to acquire a certain degree of velocity by the wind, the position recommended by M. Parent would be the best. But if the sails are intended with given dimensions to produce the greatest effects possible in a given time, we must, if planes are made use of, confine our angle within the limits of 72 and 75 degrees.
Page 6 - To every action there is always opposed an equal reaction: or, the mutual actions of two bodies upon each other are always equal and directed to contrary pans.
Page 80 - ... exactly adapted to the above series, (the line itself being supposed inelastic, and of no magnitude) the necessity of using several pulleys in each frame will be obviated, and with that some of the inconveniences to which the use of the pulley is liable. In the figure referred to, the coils of rope, by which the Weight is supported, are represented by the lines a, b, c, &c.

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