BOEING. Whether the vertical cavity for an Artesian Well is made, or the cavity of a cannon formed, or the cavity of a cylinder or barrel perfected, or a hole simply made in wood—the term boring is equally applied to all these operations.
Cannon are usually cast solid, and bored by machinery; and in an accommodated sense the term is applied to the similar operations by which musket-barrels, the cylinders of steam-engines, and other articles which are originally made hollow, have their inner sur faces turned to a perfectly smooth surface and cylindrical shape. The boring instruments of the carpenter consist of awls, which are put into soft wood, with a rotatory motion, with out removing or bringing away its substance ; gimlets and augers, which are supplied with cutting edges, and are partially hollowed, to allow of the escape from the hole of the de tached particles of wood ; and bits of various kinds, which also remove the wood, and are applied with greater power and precision by means of a crank-shaped instrument called a brace. Small holes in metals are usually bored with drills, which are formed with scraping rather than cutting edges, and are used either in a brace, a drill-stock capable of imparting an 'alternating rotatory motion by means of a bow worked by hand, or some other contrivance, or in a lathe Boring ma chines of the lathe character are too various and complex to be described here. Suffice it to say, that the perfection to which they have been brought has rendered most essential ser vice to science and manufactures, and removed one of the greatest difficulties experienced by early improvers of the steam-engine.
Of the various boring operations of the miner, that of boring Artesian wells is unques tionably the most interesting. It is performed with various kinds of chisels or jumpers, augers, and instruments suitable for extracting the detached fragments, attached to the lower end of an iron rod formed of manylengths screwed into one another ; theseinstruments are either turned round, or jumped up and down, or worked with a combination of these two mo tions by suitable mechanism, the kind of tool employed, and the mode of working, being va ried from time to time as the several strata are met with. By such means the interesting works noticed in ARTESIAN WELLS were com pleted.
Beart's boring tools, patented in 1844, are intended to be used in circumstances where the hole made by the borer can be kept con stantly full of water. The borer itself is at tached to a hollow tube instead of a solid rod, and acts as one leg of a syphon ; the other leg being an excavated channel prepared for the purpose, and kept full of water. The ar
rangement of the several parts is such, that as fast as the fragments of rock or soil are loosened by the borer, they are drawn up with the water by which they become saturated, through the tube which forms the stem or vertical rod of the borer : this, at least, is the theory on which the inventor has founded his patent.
At the meeting of the British Association in 1846, Mr.17ignolles communicated an account of a method of boring Artesian wells, invented by M. Fauvel of Perpignan. M. Fauvel had observed that in several cases of success in boring for water with solid iron rods, so soon as the spring was tapped all the triturated parti cles were brought up without the use of the auger. He inferred that if the boring could be effected by a hollow tube about two inches less in diameter than the width of the auger, communicating with an injecting force-pump by a flexible tube from the surface, a result would follow similar to that which resulted from the natural power of the rising column of water. Having tested the hypothesis, he found that the well could be bored in much less time than by the former method. The plan has since been largely adqpted, in some cases to very great depths.
An attempt was made by Mr. Gard, of Cal stock, in 1848, to produce an improved boring machine, to effect in another way the objects intended by Mr. Beart in England, and M. Fauvel in France. His boring machine con sists of a hollow cylinder to the bottom of which the boring-bit is attached in a peculiar way ; and as the rock or earth is bored, the fragments force themselves up into the cylin der, where they are retained by a valve. The cylinder does not reach to the top of the bore, but requires to be raised when full, in order that it may be emptied; it however will con tarn so large a quantity, that the necessity of raising it will occur much less frequentlythan under the usual system. Instead of joining successive lengths of rod to the boring tool, the latter is raised and lowered by a chain.
At a meeting of the Cornwall Polytechnic Society, a few years ago, Mr. Prideaux pro posed the adoption of a chemical means of facilitating the process of boring. He found. that a stream of hydro-oxygen gas applied to a piece of granite stone produced heat; and that on the application of cold water the stone became soft, and yielded to the tool. Oxygen might be superseded by common air from a pair of double bellows ; and common coal-gas might be used instead of hydrogen.
A very instructive illustration of the appa ratus employed in well-boring may be studied at the Museum of Economic Geology.