strument for the same purpose had been invented, and used with success in France, and which was somewhat on the same principle, excepting that it had no curve, it having been found that a straight instrument might be passed into the bladder of many persons.

Notwithstanding what was said of the success of this contrivance, I conceived it would be very desirable to form one which would be better adapted to the natural curve of the urethra, and with which there would be less danger of injury to the bladder in attempting to seize the stone. Under this impression I determined to make another attempt, and for this purpose I applied to Mr. Ferguson, a very ingenious Surgeon's Instrument 'maker, in Castle-Street, Leicester Square; he entered fully into my plan, and was of very great assistance in carrying it into execution, and completing the instrument hereafter described.

The instrument (Plate III. Fig. 1.) for the sake of convenience, is represented somewhat smaller than the original model; it consists, in the first place, of a tube twelve inches long, A A resembling a catheter, with the exception of its being open at both ends; B is an arm coming off, which connects the whole together, and at the same time serves for a handle. Fig. 2, is a stilet, with a knob at the end, which fills up the opening at the extremity of the canula, so as to enable it to be passed into the bladder without injury to the urethra, after which it is to be withdrawn, and the apparatus for seizing the stone is then to be introduced; it consists of a tube six inches longer, and about the eighth of an inch less in diameter than the first, the anterior part of which is made flexible, to enable it to take the curve of the canula, in the same manner as the old elastic catheters were constructed, which is by means of winding up a narrow strip of silver into a spiral form; part of this is seen at D, the anterior extremity, which, in Fig. 1, is concealed in the canula, and is represented at F F, Fig. 3. The surface of this tube is divided by ridges into four compartments, which at the same time keep it steady, and allow space for the two narrow watch springs G G, to pass between the two tubes, and prevent their catching in each other; at the extremity is a collar

E, Fig. 3, which exactly fills up the interval between the tubes, and in which there are four holes for the passage of the springs, which have a small bit at one end turned down to prevent their being drawn through, and the temper of the steel is lowered, so as to admit of their being freely bent: they are passed from within outwards through two of the knobs, and brought back by the others, so as to form two loops, with which it is proposed to fix the stone; they cross each other and pass through a ring H, which rises and falls as you increase or diminish the bow of the springs. The other ends pass down in the grooves-before-mentioned, and are fixed in the collar I. Fig. 1, by the screws K K, and by means of which they are slid up and down, either together or separately; L is a screw which fixes the collar when the stone is caught by the loops; mm is an elastic wire wound round the part of the inner tube, which is not enclosed in the canula, and serves to prevent the springs from bending outwards when pushed up; N N is a drill; the part of which that works in the curve is constructed in the same manner as the flexible part of the inner tube, but the metal is thicker, to give strength to bear the pressure necessary to perforate a stone; the other end is made of pinion wire, which passes through corresponding grooves in the pulley O, which enables it to be pushed forward at the same time that it is turned; the extremity works like a swivel in the socket P, attached to the ring R. The drill head takes off, that different sized ones may be used; they are made to cut one way only, as the flexible part, though quite firm enough when turned in one direction, in the opposite would have a tendency to unwind, if it met with much resistance.

To make use of this instrument, the canula, with the stilet in it, is passed; the latter is then withdrawn, and the second tube, with the watch springs attached, is pushed through it, and the end fixed in a hole in the upright S; the collar is then slid up, and the springs bow out in the manner represented in the plate: the springs may be worked up and down till the calculus is caught; it is then fixed by means of the screw in the collar, and in this way can be retained more firmly than with any forceps; by

having the springs of sufficient length, a very large loop may be made, and I should think without any fear of injuring the bladder; if the calculus should be small, it may be drawn out through the canula; if too large for that, it must have holes repeatedly drilled, till it crumbles into pieces small enough.

The principal advantages that this appears to possess over the French instrument before alluded to, are,

1st. Its form is better adapted to the urethra.

2nd. It can be made of a smaller size.

3rd. There is less chance of hurting the bladder with the bent springs, than with the forceps. The loops will fix the stone more securely, and if either of them should happen to be broken, both the parts can be withdrawn through the canula, and a fresh spring immediately adapted to it.

4th. The fragments, or small calculi, will pass off by the canula, without injury to the urethra; this may be assisted by injecting water, and letting it out again in a full stream.

To destroy a calculus of any size would require the instrument to be used a great number of times; but however tedious, many persons, I think, would prefer it to the dangerous operation of lithotomy, and would resort to it at an earlier period of the disease, when the stone had not acquired much bulk, and the symptoms were not so urgent as to make immediate relief necessary. Bentinck-Street, August, 1825.

ART. V.-Outlines of Geology, being the Substance of a Course of Lectures on that Subject, delivered in the Amphitheatre of the Royal Institution of Great Britain, by William Thomas Brande, F.R.S., Professor of Chemistry in the Royal Institution, &c.

[Continued from Vol. XIX., page 198.]

IV.

THERE are abundant difficulties in the way of any satisfactory

theory respecting the origin of the diluvial remains of quadrupeds,

&c., which were adverted to in the last lecture. If we consider them as having lived and died in the caves, and on the spots where their remains now occur, we must presume, either that their habits and propensities were extremely different from those of the now existent species of the same tribes; or, what is yet less admissible, that the temperature of the northern regions was formerly correspondent with that of equatorial climates. Again, if we imagine the bones to have been transported thither by water-carriage, at the time of the deluge, how, it will be asked, can they have escaped attrition?—and not this only, for they actually retain in perfection all the tuberosities and processes which enable the anatomist to recognise them. To get over this latter difficulty, it has been conceived that the bones were not transported along with the pebbles and gravel, but that they came safely packed and protected in their including carcasses, floating upon the surface of the waters, and were afterwards deposited safely upon the mud or gravel, where the flesh rotted and decomposed, and the bones remained uninjured. We know how readily this kind of transportation takes place, how rapid the carriage may be, and supposing the temperature not very high, we also know that many weeks might elapse before the carcass would sink. I shall not at present venture to give any opinion upon this question, but shall refer my audience to the works of Professor Buckland, as the advocate of the one hypothesis, and to those of Mr. Granville Penn, who has defended the other.

We may now proceed with our description of the strata, upon which the former materials are deposited: these are the supermedial rocks of Phillips and Conybeare, and include the varieties. of chalk, green and ferruginous sands, oolite or freestone, lias, and red marle or new red sandstone.

Below the varieties of clay, the position and contents of which formed the subject of the last lecture, we find the chalk which has already been stated to constitute the cavities of basins, in which the various alluvial matters are deposited. The ranges of chalk hills in the south of England are very extensive, and the land

scape which they constitute, peculiar for the smooth and rounded outline of its hills, their monotony of surface, and for the singular cup-shaped concavities and deep hollows in which their sides abound. The situation and extent of the chalk in England is best shown by reference to coloured geological maps. Salisbury Plain and Marlborough Downs form a centre, as it were, from which the chalk emanates in a north-east direction, through Buckingham, Bedford, and Cambridgeshires, and terminates on the coast of Norfolk in one direction. Another branch, interrupted by the Valley of the Humber, traverses Lincolnshire, terminating at Flamborough Head in Yorkshire.

The extreme western point of the chalk is not far from Honiton in Devonshire, whence it branches off toward the south-east to the Isle of Purbeck, and again appears, forming a ridge that crosses the Isle of Wight. Near Hungerford, in Berkshire, another range of chalk commences, and passes by Alton and Rochester to the coast of Kent, forming the cliffs between Folkstone and Deal. From near Alton, another branch passes off, and ends at the lofty promontory of Beachy Head on the Sussex coast. In this chalk district there are some considerable elevations. Near Dunstable and Shaftesbury, for instance, it forms hills nearly 1000 feet above the level of the sea. Between Lewes in Sussex, and Alton in Hampshire, there are several similar elevations. Between Alton and Dover, the highest point is about 800 feet, and the Castle Hill is about 470 feet high. The chalk cliffs near Folkstone, and those near Lyme in Dorsetshire, are between 5 and 600 feet high.

Chalk, like the strata that lie upon it, abounds in organic remains, but they are of a different and more ancient character, exhibiting many new genera, and scarcely a single species quite identical with any that now exist. They are chiefly as follow:Remains of vertebral fish, such as teeth of a species of shark.

Among the testaceous mollusca, are ammonites and belemnites, generally in the lower strata only; a few spiral univalves and several bivalves.