flexible tubes, which will follow the descending movement of the boring tube for an extent of some yards: the boring tube is worked by a rotary movement, with a turning angle, or by percussion with a jumper; the frame or tackle for lifting, lowering, and sustaining the boring-rod are of the common kind; a column of water is sent down by the pump to the bottom of the bore hole, the water rising in the annular space between the exterior of the hollow boring-rod and the sides of the bore hole creates an ascending current, which carries up the triturated soil. The boring tube is worked like an ordinary boring-rod; there is, consequently, no occasion to draw up the boring tube to remove the debris, and the boring tool never gets clogged by the soil.

The jurors of the Great Exhibition of 1851 drew particular attention to the boring tools of Mr. J. F. Lane, of Wilderz, Switzerland. Water is introduced by means of hollow rods, and mixing with the powder or small dust formed in boring, is discharged through the tool by the blow of the latter in descending, keeping the bottom clear, and ready to receive the full effect of the tool. A boring of 1,300 feet has been made with these tools, and with a facility of which the old tools are not susceptible.

The chief improvements in boring appear to have been made during the last thirty years, and although the art has been known in China during many centuries, and used to an extent which, for depth of workings, has not been exceeded in other countries, yet but one stereotyped system was invariably followed for all descriptions of rock.

The most simple method now employed is that by means of a tool similar in its actions to the common carpenter's auger: this tool is termed a wimble. It has, however, the evident fault of being only applicable to soft or yielding ground; its use is therefore extremely limited. Where great depths have to be attained, or hard ground passed through, a percussion arrangement is made use of. Under ordinary circumstances, this consists of a chisel-edged tool, similar to the common borer of the miner, attached to a series of iron rods, which, by means of male and female screws, are fitted into one another. These are lifted a certain height by a spring pole, to the end of which they are attached by a swivel joint. This arrangement may be worked by manual or other power, and is first raised and then allowed to fall against the bottom of the hole, whilst at each blow the whole set of rods are turned a certain portion of a revolution by means of a cross-head lever fitting tightly on the top rod. By a repetition of these blows, and gradually turning the boring bit in the hole, so that it shall strike various radii on the surface of the bottom, a certain portion of rock is reduced to powder; this mixes with water, forming a kind of paste. When it has accumulated to such an extent as to impede the action of the cutting tool, the rods are removed, by separately unscrewing them, and a sludge bucket to remove the powdered material is introduced in its stead. This consists of a short cylinder of the size of the hole, with a valve in its bottom opening inwards, which, being lowered to the bottom of the hole, the valve opens and the sludge or pul verized rock enters the cylinder, which is then drawn up; the valve, of course, closing on the bucket being elevated. The rods are subsequently re-introduced, and a similar series of operations again carried on.

Within a few years great advances have been made in the art of boring by the talent brought to bear upon it by Messrs. Kind, D'Eynhausen, Degousée, and Fauvelle, who have been eminently successful even where they have met with difficulties of such a nature as to entirely prevent the use of the common chisel-edged tool and iron rods.

To the use of continuous iron rods there are two great objections: first, their liability to break, from repeated percussions and vibrations through their entire length, which produce a molecular change in the iron, similar to that which takes place

in railway axles, and which has been termed the "Fatigue of metals;" and secondly, this constant percussion and tremulous action of the rod lashes it against the side of the hole. When it is remembered that this action is repeated as often as 15,000 times in a day, and continued for many months without intermission, it will be readily understood that the softer portions of the strata through which the hole has passed will be liable to crumble and give way this takes place in some instances to a considerable extent. Sometimes, also, portions of the rock get jammed between the rods and the sides of the hole, and thus entirely prevent their extraction.

To obviate this, M. D'Eynhausen has invented a slide on the rods. This is inserted at a height of five or six lengths of rod above the tool, so that it confines the shock of the fall to that portion of the arrangement. The weight of the upper rods is also counterbalanced, and they thus only serve as a support to the lower ones. The upper rods are also, for the sake of lightness, often made of wood, jointed together by male and female

screws.

M. Fauvelle has introduced improvements in this art of a remarkably novel and ingenious nature. They consist in boring with hollow rods of a size considerably less than that of the hole; down these tubes is forced a stream of water, and by this means the loss of time consequent upon taking out the rods and introducing the sludge bucket is altogether obviated; since the downward current in the tubes, striking the bottom of the hole, forces to the surface the particles of rock removed by the cutter. There is also a great advantage gained by always having a clean surface for the tool to act upon. When boring in ordinary strata, this current is forced down the tubes; but when boring through sand or gravel, the current is forced down the outside, whilst the debris ascends through the interior of the tubes. By this means stones of the size of 2 inches by 1 inch have been brought to the surface.

In point of saving of time some extraordinary results have been obtained by M. Fauvelle. A boring was made by this system at Perpignan, to a spring 186 yards from the surface, in July, 1846; the time occupied in reaching this distance was 140 hours of actual work, extending over a period of 23 days. A

similar boring at the same place, carried on by a different system, occupied 11 months.

There are, however, objections to this plan, which have prevented its more general adoption; the first is the porosity of some kinds of rock, which causes the absorption of more water than the tube is capable of supplying; another is the action of large quantities of water entering the hole from between certain beds of rock. The first would prevent the debris from being carried to the surface, from the fact of the non-existence of the means; whilst the second would so far interfere with the current as to render its action only partial. In deep borings this system appears to be very inefficient.

The next system which we shall notice is that of M. Kind, who has introduced a number of most valuable improvements and has brought the art to greater perfection than any other engineer. Among M. Kind's improvements we may notice threeFirst, the use of light wooden rods; secondly, the employment of a "free fall" percussion tool; and thirdly, the method of obtaining a core or piece of rock of the size of the bore hole, and of considerable length, which enables the operator to form a correct idea of the character and dip of the strata.

The advantage of the use of wood over iron rods is obviously their light weight, more especially when we consider that the bore-holes are usually filled with water; the wood itself soon gets saturated with moisture, and the iron screws and ferrules at the end of each render the whole mass of a greater specific gravity. than the water in which it is immersed, only to such an extent as to allow of their falling freely through the liquid by which they are surrounded.

The free fall tool consists of an ingenious arrangement by which the bit is detached from the rods when they are lifted to the height necessary for the proper fall; it then drops by its own weight, whilst the rods follow separately, and when they have been again lowered to the neck of the tool, an opposite action to that which detached it causes it to be caught and held firmly while it is being again raised to the requisite height.

The "free fall" of the tool, with a length of rod attached to it, effects, in a more perfect manner, the object of D'Eynhausen's slide in removing from the wooden rods the injurious vi

brations caused by the shock of the tool. The mode of action is

explained by figs. 1 and 4, the first showing the manner in which the upper end of the piece (A D) is taken hold of by means

of the fangs (C D), which work on the centres; the latter figure exhibiting the position of the various parts at the moment the tool is released. The tool is not shown, it is screwed into the bottom of (D). The fangs are made to bite by means of the ring and wedge (A B) being forced downwards. As this ring (B) is drawn up it immediately opens the fangs. The ring and wedge are attached to a leather piston (K), made about half an inch less in diameter than the borehole. The rods are moved

up and down in the usual way. At the end of the upward stroke a sudden motion is communicated in the opposite direction; this causes the pressure of the water against the under side of the piston to lift the ring and open the fangs. The tool falls and the rods follow at a slower speed. Having descended to the proper point, a slight upward motion producing pressure against the upper side of the piston causes it to descend with the arm and ring and close the fangs. The tool is then lifted to its position for the second fall. The fall is from 1 to 3 feet; the number of strokes per minute, with manual labor, from 8 to 16, which can be increased by the application of machinery to 20 or 25. The weight of the falling tool from 8 to 10 cwt.; the rods are about 45 feet in length, made of wood 3 inches in diameter, with iron male and female screws to unite them.

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