Elements of Technology: Taken Chiefly from a Course of Lectures Delivered at Cambridge, on the Application of the Sciences to the Useful Arts : Now Published for the Use of Seminaries and Students

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Hilliard, Gray, Little and Wilkins, 1829 - Industrial arts - 507 pages


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Page ii - DISTRICT OF MASSACHUSETTS.— to wit: District Clerk's Office. BE IT REMEMBERED, That on the...
Page 85 - Eyes of a Portrait. — The influence which the association of contiguous objects has upon our ideas, is strikingly exemplified in the eyes of a portrait. We estimate the direction of the eyes, not only from the position of the ball in regard to the eyelids, but also from the relative position of the remaining features of the face.
Page 196 - ... are in the best possible condition to resist friction. In like manner, the common obstacles that present themselves in the public roads, are surmounted by a wheel with peculiar facility. As soon as the wheel strikes against a stone or similar hard body, it is converted into a lever for lifting the load over the resisting object. If an obstacle eight or ten inches in height were presented to the body of a carriage unprovided with wheels, it would stop its progress, or subject it to such violence...
Page 427 - Carmine, the most beautiful of all the reds, is an animal substance made from the cochineal insect, or coccus cacti. It is deposited from a decoction of powdered cochineal in water, to which alum, carbonate of soda, or oxide of tin is added ; but the preparation of the finest varieties is kept secret by the manufacturers, and probably depends much upon the delicacy of the manipulations. A fine color is said to be made by adding acetic acid to a solution of carmine in ammonia. Lakes of various shades...
Page 44 - The modulus of the elasticity of any substance is a column of the same substance, capable of producing a pressure on its base which is to the weight causing a certain degree of compression, as the length of the substance is to the diminution of its length.
Page 416 - The machine has a rapid reciprocating motion, and cuts off at every stroke a wedge shaped piece of iron, constituting a nail without a head. This is immediately caught near its largest end, and compressed between gripes. At the same time a strong force is applied to a die at the extremity, which spreads the iron sufficiently to form a head to the nail. Some nails are made of cast iron, but these are always brittle, unless afterwards converted into malleable iron by the requisite process.
Page 350 - ... made to pass slowly from one end to the other of the cones, and thus continually to alter their relative speed, and cause a uniform retardation of the velocity of the moving parts.* As the roving is not strong enough to bear any violence, the spindles which support the bobbins are geared to each other, so as to prevent any deviation from the proper velocity. A more simple form of the roving frame has been invented,!
Page 66 - The common old printing press derives its power from a screw, which is turned by a lever, and acts perpendicularly on the platten, or level part, which transmits the pressure. Various improvements have been made in the printing press, by lord Stanhope and other inventors, in most of which a cast iron frame is substituted for a wooden one, being more inflexible ; and a combination of levers is used, so arranged as to cause the platten to descend with decreasing rapidity, and consequently with increasing...
Page 481 - But when it is to be exposed to the vicissitudes of weather, and still more when it is to remain in a warm and moist atmosphere, its preservation often becomes extremely difficult. Numerous experiments have been made, and many volumes written, upon the preservation of timber, and the prevention of the dry rot ; but the subject is not yet brought to a satisfactory conclusion.
Page 128 - ... with lime, and sometimes with sand and gravel. — Styles of building. The architecture of different countries has been characterized by peculiarities in external form, and in modes of construction. These peculiarities, among ancient nations, were so distinct, that their structures may be identified even in the state of ruins ; and the origin and era of each may be conjectured with tolerable accuracy. Before we proceed to describe architectural objects, it is necessary to explain certain terms,...

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