Description of the Engraving.

L, Lever. W, Water level. F, Friction wheel. D, Dynamometer. a, Main axle of the machine.

bb, Pipe which incloses it.

cc, Disk of the turbine fixed on the main axle.

ee, Curves or disks let into the platform PP.

dd, Curves on disks fixed round the circumference of the turbine, on which the water issuing out of the curves of platform PP, impinges.

ff, Bolts and screws for raising or lowering the circular sluice gg. Operation. To set the machine in motion the sluice gg is drawn up by means of the screws and bolts ff.

The water, which is continually resting on the platform PP, with the pressure of the whole fall,immediately issues out between the curve disks, and, impinging on the exterior curves of the turbine, causes it and the main axle, with all its machinery, to revolve rapidly.

In the annexed engraving, a friction wheel and friction break are attached to a lever, the vibration of which, and consequent power of the machine, are ascertained by the dynamometer.

The advantages of these machines are their simplicity and economy; they occupy very little room and can be placed in situations where a common vertical water wheel could not. The facility with which their velocities can be increased or diminished renders them well calculated for spinning, or for any mechanical operation which requires uniformity in changes of velocity ad libitum, and whereby increase or diminution of velocity may be obtained without the intervention of a train of wheels and their consequent friction and loss of power. To use the words of the commission appointed to examine the report of M. Morin, "The turbine is, of all the hydraulic machines in use, the most effective that has yet been compressed in the smallest form."* GEORGE REnnie.

New Source of Light.

M. Seguin has communicated to the Académie des Sciences, at Paris, a memoir on the distillation of animal substances, in which he states, that he has reduced the process to such a degree of simplicity, as to render it profitable for the sake of the products of the distillation. Thus, from the carcase of a horse he obtained, by destructive distillation, 700 cubic feet of gas, suitable for purposes of illumination, 24 lb. of sal ammoniac, and 33 lb. of animal black. The gas obtained was found to be composed of one part of olefiant gas and four of carburetted hydrogen, and might be preserved for months, in contact with water, without being in any way injured, or its brilliancy, as a combustible, impaired. M. Seguin found that 3,234 cubic inches of this gas, when burnt for one hour, gave twice and a half as much light as a Carcel lamp.

Atheænum.

The Clinometer.

Sir,-This instrument takes its name from two Greek words, signifying a

* Expériences sur les Roues Hydrauliques a arbre vertical appelée turbine, par Arthur Morin, Capitaine d'Artillerie, &c. &c., Metz.

bed, or strata, and a measure; it is therefore intended for the purpose of ascertaining the depth of soft mineral, or earthy, strata.

Explanation.-A, a cross piece for working the instrument; B, a strong pole graduated to feet, &c. for fixing to T a stout iron tube with an opening equivalent to one-third the circumference as shown at P. P, an inner tube to work freely upon the interior of T, of similar shape. K, K, projections for opening and shutting the instrument; S, a suitable screw for working the instrument into the ground.

A simple and efficient instrument for this purpose has long been a desideratum. If a landed proprietor or surveyor is desirous of ascertaining the nature of the subsoil of an estate, or an engineer the subsoil of the bed of a river (as in the case of the Thames Tunnel,) with the means generally em

ployed for such purposes, it becomes an operation of considerable time, trouble and expense. The landed proprietor or surveyor, goes to work by taking with him one or two men with pick, shovel, &c., who commence operations (perhaps in the centre of a fine meadow) by digging an unsightly pit some three or four feet square, and so reach the required depths. The engineer on the other hand, will, supposing him to go about the job sans cérémonie, in the method at present employed, bring with him augers, borers, &c., and by abstracting the earth by little and little, arrive at the required information. But with my instrument, the surveyor will soon accomplish his task. Throwing it over his shoulder as he would his gun, off he goes, and having fixed upon a spot, takes the cross piece, passes it through the hole at the top of the instrument, introduces the same into the ground, and works it down screw-fashion, from left to right, (the inner tube remaining shut.) After working it to the required depth, as indicated upon the stalk of the instru ment, the motion is reversed, when the resistance of the projections upon the inner tube to the surrounding earth will cause the instrument to open and to charge itself with the soil at such depth. The motion being again reversed, will cause the tube to close; when the instrument, being withdrawn, will be found to contain, pure unmixed soil, taken from the required depth, that is, the soil through which the tube was passing, when the motion of the instrument was reversed.

S

Trusting that this invention will be of considerable utility,
I am, yours, &c.

WM. JONES.

Manchester, Dec. 16, 1839.

Analysis of a piece of iron converted, by the action of Sea water, into a substance resembling Plumbago. By D. MUSHET.

In this communication Mr. Mushet gives the result of his analysis of a piece of the iron heel-post of a vessel, called the John Bull, which, by the effect of salt water, was converted into a substance resembling plumbago. This substance was of a dark brown color, and easily cut by a knife; on being exposed to a red heat, in a crucible, it lost about 20 per cent. in weight, and on being exposed to a white heat for four hours, it lost about 60 per cent. and came out a light mass of very brilliant carburet. This shining carburet was then used as a carbonaceous substance for the reduction of an oxide of iron, but was less efficacious than the same quantity of the charcoal of wood. From these and other experiments, Mr. Mushet considers 100 parts to be composed as follows:

Report, by ANDREW URE, M.D., F.R.S., &c., upon the asphalte rocks of Val-de-Travers, Seyssel, Pyrimont, &c., and their application as a mastich, in fool-pavements, roofs, aqueducts, cisterns, &c.

It is a very remarkable fact, in the history of the useful arts, that asphalte which was so generally employed as a solid and durable cement in the earliest constructions upon record, as in the walls of Babylon, should, for so many thousand years, have fallen well nigh into disuse among civilized nations. For there is certainly no class of mineral substance so well fitted as the bituminous, by their plasticity, fusibility, tenacity, adhesiveness to surfaces, impenetrability by water, and unchangeableness in the atmosphere, to enter into the composition of terraces, foot-pavements, roots, and every kind of hydraulic work. Bitumen, combined with calcareous earth, forms a compact, semi-elastic solid, which is not liable to suffer injury by the greatest alternations of frost and thaw, which often disintegrate, in a few years, the hardest stones; nor can it be ground to dust and worn away by the attrition of the feet of men and animals, as sandstone, flags, and even blocks of granite are. An asphalte pavement, rightly tempered in tenacity, solidity, and elasticity, seems to be incapable of suffering abrasion in the most crowded thoroughfares; a fact exemplified of late in a few places in London, but much more extensively, and for a much longer time, in Paris.

The great Place de la Concorde, (formerly Place Louis Quinze) is covered with a beautiful mosaic pavement of asphalte; many of the promenades on the Boulevards, formerly so filthy in wet weather, are now covered with a thin bed of bituminous mastich; free alike from dust and mud, the foot VOL. XXV.-No. 6.-JUNE, 1840. 35

paths of the Pont Royal and Pont Carousel, and the areas of the great public slaughter houses, have been for several years paved in a similar manner, with perfect success. It is much to be regretted that the Asphalte Companies of London made the ill-judged, and nearly abortive, attempt to pave the carriage-way, near the east end of Oxford street, and especially at a moist season, most unpropitious to the laying of bituminous mastich. Being formed of blocks not more than three or four inches thick, many of which contained much silicious sand, such a pavement could not possibly resist the crash and vibration of many thousand heavy drays, wagons, and omnibuses daily rolling over it. This failure can afford, however, no argument against rightly constructed foot-pavements and terraces of asphalte. Numerous experiments and observations have led me to conclude that fossil bitumen possesses far more valuable properties for making a durable mastich, than the solid pitch obtained by boiling wood or coal tar. The latter, when inspissated to a proper degree of hardness, becomes brittle, and may be readily crushed into powder, while the former, in like circumstances, retains sufficient tenacity to resist abrasion. Factitious tar and pitch being generated by the force of fire, seem to have a propensity to decompose by the joint agency of water and air, whereas mineral pitch has been known to remain for ages without alteration.

Bitumen alone is not so well adapted for making a substantial mastich, as the native compound of bitumen and calcareous earth, which has been properly called ASPHALTIC ROCK, of which the richest and most extensive mine is unquestionably that of the Val-de-Travers, in the Canton of Neufchatel. This interesting mineral deposit occurs in the Jurassic limestone formation, the equivalent of the English oolite. The mine is very accessible, and may be readily excavated by blasting with gunpowder. The stone is massive, of irregular fracture, of a liver-brown colour, and is interspersed with a few minute spangles of calcareous spar. Though it may be scratched with the nail, it is difficult to break by the hammer. When exposed to a very moderate heat, it exhales a fragrant ambrosial smell, a property which at once distinguishes it from all compounds of factitious bitumen. Its specific gravity is 2114, water being 1000, being nearly the density of bricks. It may be most conveniently analyzed by digesting it in successive portions of hot oil of turpentine, whereby it affords 80 parts of a white pulverulent carbonate of lime, and 20 parts of bitumen in 100. The asphalte rock of Val-de-Travers seems, therefore, to be far richer than that of Pyrimont, which, according to the statement in the specification of Claridge's patent, of November, 1837, contains "carbonate of lime and bitumen in about the proportion of 90 parts of carbonate of lime to about 10 parts of bitumen."

The calcareous matter is so intimately combined and penetrated with the bitumen, as to resist the action not only of air and water for any length of time, but even of muriatic acid; a circumstance partly due to the total ab. sence of moisture in the mineral, but chiefly to the vast incumbent pressure under which the two materials have been incorporated in the bowels of the earth. It would indeed be a difficult matter to combine, by artificial methods, calcareous earth thus intimately with bitumen, and for this reason the mastichs made in this way are found to be much more perishable. Many of the factitious asphalte cements contain a considerable quantity of silicious sand, from which they derive the property of cracking and crumbling down when trodden upon. In fact, there seems to be so little attraction between