A treatise on mechanics, applied to the arts; including statics and hydrostatics / By the Rev. H. Moseley ... Published under the direction of the committee of General Literature and Education, appointed by the Society for Promoting Christian Knowledge.

  • Moseley, Henry, 1801-1872.
Date:
1847
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on mechanics, applied to the arts; including statics and hydrostatics / By the Rev. H. Moseley ... Published under the direction of the committee of General Literature and Education, appointed by the Society for Promoting Christian Knowledge. Source: Wellcome Collection.

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    opposite to tliis resistance. Draw d a and d b, perpendicular to the surfaces of the two wings; then d a and d b are the direc¬ tions of the forces by which the bird impels itself forward with each wing. Take the lines d e and d f to represent these forces in magnitude, and complete the parallelogram e g f; their resultant d g (Art. 19), thus determined, is in the direc¬ tion in which the bird is made to move. If the wings he similarly extended, and the force which the bird exerts with each the same; the lines a d and b d, will make equal angles with the line p d passing through the centre of the bird’s body, and e d and f d being equal, d g will coincide with that line. So that the motion of the bird will be directly forward. 29. The forces by which a swimmer impels himself, are in directions perpendicular to the soles of his feet, and the palms of his hands. If these be equal on either side of his body, his motion is in the direction of its length, the result- c ants of both forces lying in a line passing through the centre of his body. If the force with which he moves one foot be greater than that with which he moves the other, one of the adjacent sides of the parallelogram, a'b'c'd', being greater than the other, the diagonal will tend towards the greater side, and the motion of the lower part of the body will be in that direction. If he use greater force with that hand which is on the same side the body, the resultant of the forces on the hands will, on the contrary, be from that side; and the head will move towards that side, and thus his body will be turned round. 30. The rowing of a boat presents another case of a body impelled by forces applied ob¬ liquely on either side; but having their resultant in the direction of its length. 31. The sails of a ship, may so placed, as to cause it to move in a direction greatly