Turning and Mechanical Manipulation: Intended as a Work of General Reference and Practical Instruction, on the Lathe, and the Various Mechanical Pursuits Followed by Amateurs. Vol. I. Materials, Their Differences, Choice and Preparation, Band 1

Holtzapffel, 1843 - 462 Seiten

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Seite 460 - The fracture of railway axles, by which some of the most lamentable accidents have occurred, arises from this molecular change in the structure of iron, by which the axles lose a vast proportion of their strength. The principal causes which produce this change are percussion, heat, and magnetism, and the author traces through a great number of practical cases of ordinary occurrence the joint, as well as the separate effect of these three causes ; showing that the rapidity of the change is proportional...
Seite 136 - The general colour of whalebone is a dusky greyish black, intermixed with thin strips, or layers of a paler colour, which are often almost white — very rarely the entire flake is milk-white. The preparation of the whalebone for use is very simple. It is boiled in water for several hours, by which it becomes soft enough to be cut up, while hot, in lengths of different dimensions, according to the use to which it is to be applied...
Seite 138 - The Mammoth or Elephant's bones and tusks, are found throughout Russia, and more particularly in Eastern Siberia and the Arctic marshes. The tusks are found in great quantities, and are collected for the sake of profit, being sold to the turners in the place of the living ivory of Africa, and the warmer parts of Asia, to which it is not at all inferior.
Seite 146 - The substance of the ivory is not in all cases thus injured by the balls, and Mr. Combe (Philos. Trans. 1801, p. 165,) explains in a very satisfactory manner, how a bullet may enter the tusk of an elephant and become embedded in the ivory without any opening for its admission being perceptible. This he elucidates on the supposition of the ball entering at the root, descending into the hollow, and being covered up by the growth of the layers, which are...
Seite 74 - ... birch-tree is remarkable for being harder and more durable than the wood itself, amongst the Northern nations it is used for tiles for roofs, for shoes, hats, &c., and in Canada for boats. The Russians employ the tan of one of the birch-trees to impart the scent to Russia leather, which is thereby rendered remarkably durable. The inner bark is used for making the Russia mats.
Seite 144 - After the most careful scrutiny on the outside of the tooth, however, the first cut is alviayt one of a little anxious expectation, as the prognostics are far from certain ; and, before proceeding to describe the preparation of ivory, I will say a few words of its internal appearance when exposed by the saw. " The African ivory, when in the most perfect condition, should appear, when recently cut, of a mellow, warm, transparent tint, almost as if soaked in oil, and with very little appearance of...
Seite 92 - Mahogany, (Swietenia senegalensis,) from Gambia, is a more recent importation ; it twists much more than either of the above, and is decidedly inferior to them in all respects except hardness. It is a good wood for mangles, curriers' tables, and other uses where a hard and cheap wood of great size is required : it admits of being turned equally as well as the others. African mahogany is the wood of Khaya senegalensit, a genus very closely allied to the Swietenia.
Seite 105 - The bark of the sandal-wood gives a most beautiful red or light claret-coloured dye, but it fades almost immediately when used as a simple infusion ; in the hands of the experienced dyer it might, it is supposed, be> very useful. There are woods described in the French works as red sandal-woods, and one specimen is so marked in Baker's collection ; probably they are varieties of red saunders or sapan woods.
Seite 82 - Gymnocladus canadensis ; the wood is compact, of a rosy hue, and used by cabinetmakers. CORAL-WOOD, says Bergeron, is so named from its colour. When first cut it is yellow, but soon changes to a fine red or superb coral ; it is hard, and receives a fine polish : he also speaks of a damasked coral-wood. It is difficult to associate these with the red woods ; they are perhaps, from the descriptions, nearest to the cam-wood from Africa. The...
Seite 446 - I" the coprer-bit have not been previously tinned, it is heated in a small charcoal stove or otherwise to a dull red, and hastily filed to a clean metallic surface ; it is then rubbed immediately, first upon a lump of sal-ammoniac, and next upon a copper or tin plate. upon which a few drops of solder have been placed ; this will completely coat the tool ; it is then wiped clean with a piece of tow, and is ready for use. In soldering coarse works, when their edges are brought together, they are slightly...

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