should tint the cheek of a mathematician of celebrity, for looking at the endeavours of a private individual, I confess I am at a loss.

I may now ask, how and where can I give publicity to my geometrical and conclusive demonstration of this problem, which has bid defiance to the learned for 2000 years, since it is obstinately and generally pronounced to be an impossibility?

My solution is not an approximation encumbered with an interminable decimal, but a conclusion brought out clearly, finally, and mathematically. Yours, &c.

Burlington-Arcade, Nov. 7, 1831.

ARTHUR PARSEY.

[We must again say to Mr. Parseyfor whom the style of his letter has inspired us with a degree of respect, which his advertisement was far from bespeaking-Why not publish at once, and "shame the fools?" There is no other way. If he can find no better medium, we shall willingly give his demonstration a place in our pages, where it will be read by hundreds perfectly qualified to pass a sound judgement upon it.-ED. M. M.]

MR. GURNEY'S STEAM CARRIAGE.

Mr. Alexander Gordon, Civil Engineer, has, in a letter to the Times, of the 7th instant, given the following explanation of the circumstances which have led to the stoppage of Mr. Gurney's steam carriage between Cheltenham and Glou

cester:

"During the last session of Parliament, while the Reform bill occupied so much of its attention, there were upwards of 100 private turnpike bills, laying prohibitory tolls on steam-carriages, in some cases amounting to the extraordinary toll of 24. at each gate! The Cheltenham Roads' Bill is one of those passed, and, in consequence of this and some farther opposition, Mr. Gurney petitioned Parliament, and the petition was immediately referred to a select committee, for the purpose of enquiring generally into the subject. From the Minutes of the Evidence, it appears, that loose stones were laid on the road at extraordinary depth for many yards; that the steam carriage

111

went through them twice carrying twenty passengers each time; that the third time (the stone being now 18 inches deep) it broke the axle. The horse coaches were stopped in the stones, and the passengers obliged to get out; and waggons were obliged to exchange horses to get through; the mail was also stopped. In consequence of these proceedings, the steam carriage was removed. I will only further add, that the public were taken from Gloucester to Cheltenham at one half the price charged them by the other coaches, and that every attempt prior to this was made by interested persons, to prejudice the public and stop the carriage, all of which failed up to the passing of the above bills, and the filling up of the road."

DYNAMOMETERS.

Sir,-The assertions I made at the beginning of my letter on the Hydraulic Dynamometer were merely theoretical, as the luminary, Kinclaven, might have perceived, if he had chosen to read them impartially. The only portion of that communication which I ever meant to represent as describing anything practicable, is the last, commencing with the mechanical description. Though I should be sorry to occupy your pages uselessly, it will be nothing but right to mention, that I consider my observations at page 5 justified, theoretically, if it be admitted that water is not perfectly incompressible. In the absence of access to sufficient scientific information on this head, I am not at present able to assert anything positively here; I believe, however, it has been ascertained experimentally, that water is compressible, though not easily, by mechanical pressure. Admitting this, then, I consider it may readily be shown, that taking depths in arithmetical progression, the corresponding densities will be in a geometrical; for there is no reason why the mathematical investigation applicable to the atmosphere, should not obtain, in the present case, though the increase of density with the depth be so minute that no practical advantage can ever be taken of it, and I never said it could, though Kinclaven has, with a great deal of conceit, attempted to make it appear otherwise.

In the hope that these remarks may prove sufficient to repel the charges brought against me in so amusing a manner by the champion of the "old

light," and to vindicate, in a theoretical sense, the truth of my assertions, I shall feel obliged by your inserting them. Yours, &c.

FIXING AND VARNISHING DRAWINGS.

Sir,Allow me to suggest, through the medium of your useful Magazine, an improvement in varnishing prints, as suggested by your correspondent, at page 61. The spirit varnish, if not laid on in a warm room, or before the fire, will turn white; but I have always found a varnish of equal parts, Canada balsam and spirit of turpentine, mixed together, and applied after the solution of isinglass is quite dry, to produce a most beautiful gloss; and should the drawing or print at any time become dirty, it will bear washing with soap and sponge, the same as an oil painting.

Yours, &c. 29, 1831.

Chelsea, Oct.

W. BARTLETT.

SIMPLE AND CHEAP STEAM-BATH.

We have given, in a preceding page, Dr. Ucellis' mode of curing the cholera by the steam-bath; and we here extract from the same source the following simple and cheap method of constructing one of canvass alone:

"Place two wooden or other common chairs, so that the patient reclines upon one, whiles his legs rest on the other: let a pole be fastened to the backs of each of the chairs for the support of a frame of stout canvass, which is to enclose the whole the lower part of the canvass is to trail on the ground, the upper part is to be kept extended by means of an oblong hoop, and an aperture is left, as above described, to admit of the head or face of the patient remaining out. To fill the bath with steam, the mode described in the letter of Dr. Ucelli, may be employed, by introducing a vessel of water, furnished with a tube and stop-cock, so as to admit of the water being made to drop at pleasure upon the hot irons or brick, which will in a very short time generate a sufficient of steam; or a closed kettle may be made to boil, and the steam conveyed under the canvass cover by means of a tube connected with the spout, and furnished with a stop-cock, taking care to lift off the lid of the kettle previous to stopping the course of the steam into the bath. The following will be found an ex

peditious and easy method:-Let a kettle be made to boil on the kitchen, or any other convenient fire; place it afterwards close to the bath, upon a triangle, over a pan of lighted charcoal, which is to be fanned so as to keep up the boiling; or one or more oil or spirit lamps may be placed under the kettle, for the same purpose. A short cloth tube or hose, pro⚫ ceeding from the canvass cover, is to be tied fast round the spout of the kettle, for the conveyance of the steam, the course of which can at any time be stopped, by tying a string round the hose, or removing it from the spout of the kettle."

Important to Coal Owners; Explosions rendered Impossible. Sir, I shall feel obliged if you can favour me, through the medium of your Mechanics' Magazine, with the names and residences of a few of the great coal mine proprietors; wishing to call their attention to a discovery which I have made of a means of rendering explosions in coal mines utterly impossible, under every circumstance, and without the use of any of the contrivances hitherto devised, such as the Davy lamp, &c. I am about making a model, which in due time will be made known to your scientific readers; but I may observe, that the machinery requires no trouble, costs very little, and instantly removes all anxiety from danger.-Yours, &c. G. S. S., Enfield, Nov. 2, 1831.

[The principal proprietors of coal mines in the North of England, where explosions are of most frequent occurrence, are the Marquis of Londonderry, the Earl of Lonsdale, Lord Durham, Sir Matthew White Ridley, Bart., and Wm. Russell, Esq., M.P.]

Alarums; Hints for Improving. Sir, I would recommend your correspondent, W. O., (p. 73) to push his ingenuity a little farther, and endeavour to make his alarum a little more perfect; the production of the light is effected in a very bungling manner. By reference to your second volume, p. 406, he will see what has already been done in this way. I would also call his attention to the following passage from Bishop Wilkins' Mathematical Magic; the writer, speaking of the great importance and utility, as well as ingenuity, of such horological contrivances as had fallen under his notice, either by observation or report, says, "of this nature likewise was the alarum mentioned by Walchius, which, though it were but two or three inches big, yet would both waken a man, and of itself light a candle for him, at any hour of the night." By this, W. O. will perceive, that he has not yet quite equalled the performance of the ancient mechanics; I hope he will persevere until he not only equals, but surpasses them.-Yours, &c., WM. BADDELEY.-Loudon, November 7, 1831.

INTERIM NOTICES.:

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LONDON: Published by M. SALMON, at the Mechanics' Magazine Office, Wine-Office-court, (between 145 and 146) Fleet Street, where Communications (post paid) are requested to be addressed. Sold by G. G. BENNIS, 55, Rue Neuve, St. Augustin, Paris.

M. SALMON, Printer, Fleet Street.

HENDERSON'S IMPROVED FRANKLIN

CLOCK.

Sir,-The accompanying drawings represent certain improvements which I have lately contrived in the Franklin clock; but before proceeding to my description of them, it inay perhaps not be out of place to offer to the notice of the reader, an abridged account of the original invention, and of the improvements in it suggested by Mr. James Ferguson.

Dr. Franklin contrived that his clock should indicate the hours, minutes, and seconds, with two hands; and only three wheels and two pinions in the whole movement. Fig. 1 is a view of the dialplate, omitting the external circle of 60 divisions. The hours are engraven on the dial-plate, in spiral spaces, along two diameters of a circle, containing four times sixty minutes. The index S makes a revolution round the dial-plate in four hours, and indicates the hour, minute, &c., from any particular hour from which it has passed to the next following. Thus, the hour exhibited in the view, fig. 1, is either 16 minutes past XII, IIII, or vIII. This clock was not made to be wound up by a key, but by a line going over a pulley on the axis of the great wheel, as in common 24-hour clocks. Clocks constructed after this principle have been found to measure time extremely well; but they are subject to the inconvenience of requiring frequent winding up, as also to considerable uncertainty as to the particular hour pointed to by the hand.

Mr. Ferguson proposed to remedy these inconveniences by the following arrangement: On the axis of the first or great wheel he fixed a flat circular plate, which revolved along with it once in every twelve hours. On the face of this plate the twelve hours were engraven; and each hour as it came round was seen through an opening made in the dialplate a little below the centre. This first wheel worked into the leaves of a pinion, which drove a second wheel, that made one revolution every hour, and carried on its axis a hand that pointed out the minutes on the periphery of the dial plate. This second wheel took into the leaves of a pinion, which drove the crown or swing

Fig. 1 illustrates both the Doctor's clock and my improvements, and is therefore applicable to both descriptions; only, it will be observed, that the hours are extended further from the centre than in the original Franklin clock,

wheel, and had a circle fixed on its axis, which made a revolution every three minutes, and was therefore divided into 180 equal parts or seconds; and as each second came round it was seen through another opening in the dial-plate, a little above the centre, in the same way as the hours were exhibited. A clock of this construction will go a week without winding up, and always point very distinctly to the true time. Mr. Ferguson acknowledges, however, that there are two disadvantages attending it, from which Dr. Franklin's is free. When the minute-hand requires to be adjusted, the hour-plate also has to be set right by the help of a pin. Again, the smallness of the teeth in the crown or swing-wheel causes the pendulum-ball to describe but small arcs in its vibrations, and the momentum of the ball is consequently less, and the times of the vibrations more affected by any unequal impulse of the pendulum-wheel on the pallets. Besides, the weight of the flat plate on which the seconds are engraven, loads the pivots of the axis of the pendulumwheel with a great deal of friction, which it is desirable to avoid.

Mr.

From this description it will be seen, that while by the original Franklin clock a person may be mistaken as to the true time, four hours, he is subjected by the adoption of Mr. Ferguson's improved edition to a new sort of difficulty whenever the clock requires to be set. Ferguson's clock having one index and two moveable circles, must be considered as having, in fact, three indexes; and all three together accomplish only what Dr. Franklin's two indexes do. Keeping: this in mind, I am inclined to think the original arrangement with two indexes would be the betterof the two, provided only the true time could be exactly indicated by it. To effect this with a common Franklin clock is what I have been labouring at for some time past; and the municating, through your medium, to the result I have now the pleasure of compublic.

Fig. 2 exhibits a section of an index, which, if applied to a Franklin clock with only three wheels and two pinions, will at all times (when the clock is kept going) point specifically to the true hour, i minute, or second. AA is the hand, represented, for the sake of greater distinctness, as twice the size of that in fig. 1.1 B is a brass socket or tube, to which is

made fast, as in other clocks, the hand AA. This socket B is placed on the arbor (not upon a square, but on a round arbor, that it may be set when required) of the first or great wheel, and is carried by its motion round the dial-plate once every four hours. Under the hand AA are three short projecting studs, marked 1, 2, 3, through which there passes a finely-finished steel rod G, which is screwed into stud 1. Stud 3 has a pretty wide round hole drilled into it—so wide that it admits a long brass tube D to slide freely through it, either backwards or forwards. Round this small brass tube there is coiled a thin and very flexible steel spring, which presses against stud 3, and the square piece which is attached to the other end of the tube immediately under S. This square piece has a thin slit cut into it, for the admission of a small sharpedged friction-pulley (indicated in the engraving by the dark line drawn through it) which pulley rolls into the spiral on the dial-plate, fig. 1, which is cut into it about the 1-16th part of an inch (the mode in which this pulley works in this spiral will be mentioned in its proper place). To the left of the steel rod G is a small conical tube C, which moves backwards and forwards, on a square part at the end of the rod that keeps it from turning round; behind is attached a spiral spring, also attached to stud 1, which confines the tube C to its proper place.

We will now suppose the hand as thus constructed, to be put on the dial-plate, and the small traversing-pulley (before mentioned) into the exterior spiral. The revolution of the hand, or index, round the dial, will bring the friction-pulley nearer and nearer to the centre each revolution, while the small circular piece of brass, marked S, (intended to represent the Sun) being connected with the piece containing the friction-pulley, will keep always moving between the spirals, and thus advancing to the true hour. In fig. 1 the time exhibited is in the minute circle 16, and the little circle S is advancing in the spiral toward I; the time is thefore 16 minutes after 12; and so of the rest. The circle S is always advancing to the hour, and the point on which it slides to the minutes. The slit seen below, S, in fig. 1, is that which allows the piece S to follow the direction of the friction-roller.

115

We will next suppose the hand to have made so many revolutions round the dialplate as will bring the S above the hour XI; the friction-pulley underneath will then have been brought into the interior. spiral, having reached the eleventh hour. The following is the contrivance which causes the piece S, and the friction-pulley, to take their place again on the exterior spiral, as presently seen in the engraving Imagine the friction-pulley to occupy the interior spiral, just against the hour x1; the gradual revolution of the pulley in the spiral groove will then have brought the end of the tube D forward to the conical tube C; it will begin just to touch C, when S indicates the hour x1; and by the time that the index reaches the xI hour, tube C will have been pressed gently against the spiral spring attached to it. So that a broader surface on C will be presented to the pin E, (seen in both figures); and when C comes into contact with this pin, it will lift the index so far from the face of the dial-plate as to allow the friction-roller to escape from the interior to the exterior groove, which lift will just be in proportion to the depth of the spiral on the dial-plate, say 1-16th of an inch, which will not be observable from the slow motion of the hand. the upper surface of the hand at E, fig. 2, is a long spring reaching to the bottom of the slit, which keeps always a gentle and equable pressure on the friction-roller while traversing the spiral groove. The hand is jointed between B and stud 1, as marked in the section by the letter n. The spiral spring wound round the long tube D, will, when the hand is lifted up, and the pulley outof the spiral groove, exert itself and cause the piece S and pulley to take their place on the exterior spiral; the conical tube C will then, in common with the other parts, regain that appearance as seen in section fig. 2.

On

to

The spring-work of this hand should be made of the slenderest materials. A spring, double or triple that of a watchbalance, would have sufficient energy exert all the force required for a hand the same size as that in the engraving; and a piece of thin watch mainspring would suffice for the spring F.

In the Franklin clock the seconds are generally indicated in a circle in the arch of the plate; but it being both awkward and inconvenient to have the se