This will continue to descend, unless the ground is very hard, or full of stones, when it becomes necessary to drive, and by changing its position occasionally it is made to revolve. After the first hole has been well opened, the chisel is changed for a cylindrical auger, which draws up the earth that the chisel has separated; the earth entering at the bottom fills the cavity of the auger, and, as it cannot escape, it is discharged at the top, and finally drawn up as occasion requires. There are many varieties

of instruments, all of which have a screw at the upper end, lapped to one thread, and therefore easily fitted into the various rods. The instruments vary in their form according to the material being pierced. The common tools consist of a pick, one end of which is used as a hammer, and called a pool; the gad, which has a steel wedge; and a shovel which usually has a pointed form, for penetrating hard and course rubbish. The borer is an iron bar, tipped with steel, formed like a chisel, and is used by one man, holding it straight in the hole made to receive it, and giving it a constant rotation on its axis, whilst another strikes the head with an iron mallet. The hole is constantly cleared out by a scraper, which is a flat iron rod, turned up at one end. In boring the well at the abattoir, at Grenelle, near Paris, the sounding-rod, which was composed of separate pieces connected together, soon became of great weight; every time the chisel was raised, and the shell or apparatus lowered to bring up the broken earth, it was necessary to take all the parts of the rod to pieces one by one, and bring them to the surface. This tedious process had to be gone through every time the chisel was detached, and the shell for removing the broken earth was lowered. During the latter part of the operation, the sounding rod of the well at Grenelle weighed upwards of 63 tons, and this enormous mass was obliged to be raised after each successive stroke at the bottom of the well.

I will now briefly refer to the various improvements made in well sinking up to the present time. The list of English patents which have been taken out for earth-boring machines contains the names of James Ryan, who took out a patent in 1805; John Goode, 1823; Robert Breart, 1844; Wm, and Colin Mather, 1845; Wm. G. Gard, 1847; Charles Gotthelf Kind and Charles Alexis de Wendel, 1850; Wm. Edw. Schottlander, 1852; Jno. Worthington and Fennel Allman, May, 1854; and Colin Mather, Oct., 1854. In addition to these may be mentioned well-known well borers, although their improvements are not patented in this country, and amongst them Easton and Amos, and D. Greenley, London, Fauvelle, Perpignan; J. F. Lane, Wilderz, Switzerland; Mulot and Son, Paris; and John Thompson, of Philadelphia.

Mr. Breart describes certain improvements, by which the earth cut by the boring tools at the bottom of the shaft, shall be immediately removed by a stream of water, in order to prevent the necessity for so frequently raising the boring rod. He proposes to pass water down a hollow syphon pipe from a small reservoir at the top, so that as the water ascends the other limb of the syphon, it may bring the particles of the earth to the top. There are evidently many difficulties to be overcome in this plan, and as it does not appear to have been much used, they have probably been found to be insurmountable.

Messrs. W. and C. Mather's improvements of 1845 consist of a new arrangement of cutting tools in a boring head. A shell pump, and a new method of giving a percussion motion to the boring instrument by means of a flattened rope round a winding drum, and actuated by the piston of a steam engine.

Mr. Gard's improvements consist in using a cylindrical shaft, with cutters attached, made with a single bevil, inclining inwards; above the cutters is ball valve, fitting into a circular aperture, and so

arranged that when the machine is worked, the borings are forced through apertures up the cylindrical shaft above the cutters, and past the ball valve, which brings the whole to the top. This machine is worked by a rope or chain, run round a fly-wheel. Messrs. Kind and de Wendel's improvements consist of-1. A novel construction of boring tool.—2. A method of withdrawing a clod of earth, to ascertain the nature of the soil at any required depth.-3. A compound boring tool for shafts of large diameter.— 4. A scraper for striking the soil to the centre of the tool.-5. Improvements in boring shafts of a cylindrical form, by the employment of oak cylinders and iron. The former are constructed like barrels, and retained in their proper position, one above the other, by broad rings or hoops of iron; and the latter have internal flanges, by which they are bolted together. By an ingenious arrangement of flanged teeth, solid cores of hard material are bored, and brought to the surface. This machine is extensively used on the Continent, and its use has effected a considerable reduction in the cost of boring for mining purposes and geological research.

Mr. W. E. Schottlander's patent (a communication) consists in the use of boring-rods, fitted inside hollow cylinders the boring tool being of a screw shape, and so attached to the machinery at the top of the well as to receive, by the turning of a winch handle, a rotary motion round its axis, at the same time as it is progressively forced downwards. Additional rods and hollow cylinders can be attached as the boring increases in depth. For the purpose of removing the core of earth from the interior of the boring-rods, a double set of pipes may be employed, the inner ones being cleansed and returned.

Messrs. Worthington and Allman's patent claims the use of any kind of drills; bits, or tools, for boring when they receive a rotary or reciprocating motion, and the making of bits, drills, and boring tools,

partly of iron and partly of steel, to prevent the necessity of frequent sharpening. The first and most important part of this patent is the same as Schottlander's.

M. Fauvelle's improvements were described in a paper written by M. Arago, and read by Mr. Vignoles, at the meeting of the British Association in 1846. The apparatus is composed of a hollow boring-rod, formed of wrought iron tubes screwed end to end. The lower end of the hollow rod is armed with a perforating tool, suited to the character of the strata. The upper end of the hollow rod is connected with a force pump by jointed or 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 1,300ft. has been made with these tools, and with a facility of which the old tools are not susceptible.

Mr. John Thompson's improvements consist of a

cylindrical iron bar, nearly filling the bore hole, and about 5t. long, to the bottom of which is attached a chisel for drilling. On the top of this cylinder is a swivel, with a square iron bar, about 4ft. long, and lin. each way passing through an elliptical steel spring, and fixed to a rope. The elliptical spring is of four strips, 18 or 20 inches long, and embraces the side of the bore hole. The lower disc has a round and the upper a square hole for the bar to work in ; the spring acts as a brace by pressing outwardly, and remains in a fixed position while the machine is at work.

Well-sinking and earth-boring will, under various circumstances, present many difficulties, and the engineer who has the direction of large works will, in all cases, require to bring to bear a large amount of practical knowledge, not only of the various kinds of strata through which he has to cut, but a practical adaptation of the most suitable boring tools to be used in each case. The subject is one of great and increasing importance, and if I have succeeded in presenting in a brief form a general view of the subject, and a condensed statement of some of the labours of those to whose ingenuity and skill we are indebted for the improvements which have been made in well-sinking and earth-boring, I shall have succeeded in some degree in the object I had in view.