but a negative rotation; thus, let the person occupying the chair observe a mark on the outer edge of the spindle or axis on which it is hung, he will perceive this mark to be continually running round the circumference of the circular provision made in the chair to receive the said spindle, and that every revolution the machine makes, the mark will have traversed the circumference of the hole, the chair at the same time being apparently motionless; then stop the machine, let the observer alight, and again produce the same effect while it is stationary; this can only be accomplished by causing the chair to revolve round the spindlean absolute demonstration,-that whenever, and under any circumstances, such an event takes place, the chair must have à rotation on its OWN AXIS. Again, let Nautilus contrive that the chair be secured to the arm on which it is hung, while at its lowest depression; then let him elevate it to its extreme height-in this position it will be bottom upwards, now let him release the chair, and he will have invincible evidence of its rotation on its own axis, by its falling into the position it would gradually have acquired during its ascent, had it been left to the control of its own action.

Again he says, "If this suffice not, Jet Mr. Mackintosh hold in his hand a bottle of port wine, with which he shall describe an orbit with its crusted side always opposite the flame of a candle; this may be done by the person holding it walking round the candle with the bottle between him and the flame; in this position it will resemble the ball. Now to the bottle securely fix a string, which must be attached to the stem of a candle. If the bottle in its revolution round the flame winds the string around it, then in its path will it have a rotation on its axis; if not, vice versa, Did the bottle take up the thread, which it would do if made to describe an orbit in common, then would it revolve on its axis to a certainty; but in this case the similitude ceases, the bottle being an independent body following its own laws of rotation, and the ball revolving round the axis of that body of which it forms but a part.

The last argument Nautilus adduces is foreign to the point in question, and which, as he is endeavouring to substantiate his position by a course of inductive reasoning, will signally fail. I will ad

mit, however, for the sake of brevity, what he assigns, and take him upon his own grounds; namely, "that a small globe, having a string tied round its equator, and a piece of yarn attached to one of its poles, will, when caused to revolve by swinging it round by the equatorial cord, twist the yarn into a fairlyspun thread; thus it is proved to have a rotation on its own axis. Now, let Nautilus fix a piece of yarn to his axis of the ball of lead, and again to any other part of the wheel, if he waits for the spun thread in this instance, he must stay till the ball has rolled around it-the arm on which it is fixed, or two hills be created without a valley. One more illustration: let the person occupying the chair of the "merry-go-round," hold in his hand the same piece of yarn which, as in the above case, shall be fixed to another part of the machine; he will soon find the yarn become a fairly-spun thread. What better proof can be required, that the chair has a rotation on its own axis? How, then, can Nautilus so positively assert the ball to have a rotation, &c., when the practical results are so diame trically opposite in their effect? I have been induced to trouble you thus much, from no other motive than a desire to correct error whenever it is in my power; and were so scientific and philosophical a journal as is the Mechanics' Magazine, allowed to pass with so mechanical a blur upon its pages, I should fear for the enviable reputation it possesses. It is in consonance with this conviction, that these observations have been elicited. I trust, should you deem them worthy the valuable space they will occupy in your highly entertaining periodical, they will be a means of rectifying an erroneous impression, likely to be caused by the perusal of the letter to which they apply.

I have not the remotest intention to defend your very intelligent correspondent, Mr. Mackintosh, in this new theory; but when he is so unjustly attacked, and that in such dogmatic verbosity, I cannot resist the incliation to become a volunteer in his behalf. Is not opposition the whetstone of argument, and controversy the sport of truth? If so, good will accrue from evil, and Nautilus have no reason to regret the publication of his letter. S. W. S.

Leamington, Jan. 28, 1837.

NOTES AND NOTICES.

Defective Vision.-It is well known that Goethe pursued for a series of years a course of experi men's in optics, which terminated, in his opinion, in annihilating the Newtonian system, the in mortal author of which he took upon himself to treat with so little ceremony, both in prose and verse, as materially to lessen his own claims to respect. One investigation which he pursued, in conjunction with Schiller, was into the cause of that inability to distinguish colours, which appears to be one of the most common defects of vision (and which has been the subject of communications to the Mechanics' Magazine on the 3rd of December and the 21st of January last). The result at which they arrived is stated by Goethe in his Tag-und Jahres-Hefte (Day-and-Year-Papers, a sort of summary of the events of his life), to have Been this-that in all cases this defect arose from an incapacity of perceiving one particular colourBlue.

How to thaw Frozen Pumps.-Mr. Akrill, an ingenious mechanic of Boston, communicates the following simple method of thawing frozen pumps, and preventing them from freezing. Put a bung into the nozzle of the pump, and two or three.handfuls of salt into the barrel: if put in over night, take out the bung, and pump out the salt and water, after which the pump may be used. To be repeated when necessary.

Removing Stains from Prints, &c.-We have received the following communication from an intelligent correspondent:-"I have, by accident, discovered what might be useful to some of your readers to know-that the clear solution of chloride of lime, diluted with twice its bulk of water, will effectually and expeditiously remove stains from prints and printed paper. Instead of the ordinary process, which is expensive and tedious, first soak the print in clear water, till it lies smooth; then remove it into a dish, large enough to hold it flat, filled with the solution diluted as above:-the stains will disappear in a few minutes, when again soak the print in clear water, to free it from the chloride of lime, and then dry it between sheets of blotting-paper. By this process I have bleached twelve prints, and letter-press belonging to an expensive book, which had been damaged by rain and sea water." "-West of England Conservative.

Reason why Arcs of Ellipses or Circles are Pleasing to the Eye.--Professor Muller, of Berlin, has, in a late course of lectures, offered a simple aud mechanical explanation of the universal admiration bestowed on these curves. The eye, he observes, is moved in its socket by six muscles, of which four arc respectively employed to raise, depress, turn to the right and to the left The other two have an action contrary to one another, and roll the eye on its axis, or from the outside downward, and inside upward. On an object being presented to the eye for inspection, the first act is that of circumvision, or going round the boundary lines, so as to bring consecutively every individual portion of the circumference upon the most delicate and sensitive portion of the retina. Now, if figures bounded by straight lines be presented for inspection, it is obvious that but two of these muscles can be called into action, and it is equally evident that in curves of a circle or ellipse, all must alternately be brought into action. The effect then is, that if only two be employed, as in rectilinear figures, those two have an undue, share of labour;, and by repeating the experiment frequently, as we do in childhood, the notion of tedium is instilled,. and we form gradually a distaste for straight lines, and are led to prefer those curves which supply a more general and equable share of work to the muscles.

Leaving a net profit of. To which add the surplus left from the preceding half-year of

Total

£125,279 5 79,628 0

9 0

£45,651 5 9

1,127 15 2 £46,778 0 11 From this sum the Company has declared a dividend at five per cent., payable on the 8th February, leaving a surplus of 6,3781. 15s. 4d. towards the next account.-Manchester Times.

A Foreign Grand Junction Railway,-all abroad. -Some time ago it was confidently asserted that the Pacha of Egypt had fully determined on the construction of a grand railway across the Isthmus of Suez, and England was actually visited by an agent, who contracted with iron-masters here for the supply of a considerable quantity of ailway. bars, which were intended, it was said, for that destination. It now appears that the Pacha, if he ever entertained the idea, has entirely abandoned it, as he is now using the rail bar which was to have had the honour of, as it were, uniting Europe with the Oriental World, for the paltry purpose of making several short railways in the vicinity of Cairo; one of which is for the supply of his capital with stone. The canal which he was once going to dig across the Isthmus has apparent shared the same late as the railroad.

"A. B.'s" only safety is in keeping his invention as secret as possible, and in delaying the construc tion of his machinery until the specification of his patent is enrolled.

Erratum.-In p. 5, of the Mechanics' Magazine Advertisement sheet for December, the price of Mr. Hawkins' translation of "Camus on the Teeth of Wheels," instead of 10s., should have been 10s. 6d.

The Supplement to Vol. XXV., containing Title, Table of Contents, Index, and Plate of Specimens of English Medallic Engraving by Mr. Bate, was published on the 1st of December, price 6d.

number of fires in chimneys, in the vicinity of their respective stations; but being known to be accidents of this description, they were attended accordingly; whereas, those included in the above table were represented to be larger fires, and caused a general turn out of the men, &c.

The number of false alarms, by a singular coincidence. is the same as reported last year, and they have been much of the usual character. Several have been given without the slightest foundation, from motives of sheer mischief, regardless of the inconvenience to which a number of men (at all times hard enough worked) are put; or of the expenses which are thrown upon the Fire-Establishment by hoaxes of this description; to say nothing of the protection of which the public are deprived, by sending off the firemen and engines from their accustomed stations on distant useless errands. One fellow of gentlemanly exterior, who gave his name John Watts, has been in the habit of amusing himself and annoying the firemen, by playing off tricks of this sort at different engiue-stations. Upon the last occasion (July 22nd,) he called at the Farringdon-street station, and stated that Messrs. Day and Martin's Blacking Manufactory in High Holborn was in flames. The engine and men from that and other stations proceeded immediately to High Holborn, but found on their arrival no fire, nor any appearance to justify the slightest apprehension of danger from any such cause. An ex

ample will be made of the first person who is found thus abusing the readiness of the firemen to afford assistance whenever and wherever required.

Atmospheric phenomena have had their share in producing groundless alarms; two of these were of a very singular character. The first occurred on Sunday, September 25th, about half-past four o'clock in the morning; when a red glare of light in the sky occasioned a general alarm of fire eastward to be given to the firemen all over the metropolis; no certain information being obtained as to the locality of the fire, the engines were driven at conjecture-some along Ratcliffe Highway-some down the Com.. mercial-road-while others went to Mile End. On reaching these points, however, the first appearance became gra

dually fainter, and the firemen came in sight of a second light, which appeared more southerly, and which really proved to be a large fire that had just broken out at Messrs. Ewbank and Co.'s Rice Mills and Granaries, at the head of the Grand Surrey Canal Docks.

Some little delay was occasioned, by the engines being on the wrong side of the river; they were, however, got round as quickly as possible. Meantime the firemen were shipped across, and the floating-engine, which is stationed in this part of the river, was set to work, and rendered great service.

The other atmospheric phenomenon was, however, of a far more extraordinary description; the former was occasioned by the sun's rays, but the one we are now about to describe was a variety of the Aurora Borealis. About half-past 8 o'clock on Tuesday evening, Oct. 18, a sudden cry of "Fire" burst forth from hundreds of tongues, in consequence of a crimson glare of light appearing in the horizon; the apparent danger was north-east—and so strongly did the light resemble that of a fiercely-spreading conflagration as to deceive the oldest firemen. The alarm was greatly strengthened by what seemed to be clouds of smoke rising up after the crimson glare, and breaking and rolling away beneath it.

Thirteen engines and a large body of firemen were turned out in search of the dreadful conflagration, the existence of which no one doubted. Immense groups of people thronged the streets, and pedestrians as well as vehicles kept pouring down from the west-end of the town to see the fire.

The alarm upon this occasion was not confined to London; at Dublin,* Leyden, Utrecht, Strasburg, Troyes, Rennes, and at Nantes, the same alarm was created, attended with a similar turn-out of the firemen, military, &c. This singular phenomenon appears to have been witnessed simultaneously at these, and many other places in England, France, Germany, and Prussia, having from 470 to 54° of north latitude, and being from 1o east to 8o west of Greenwich. It was not visible at Paris. It may be in the recollection of many of your readers that a similar appearance of

* An interesting account of this phenomena as seen at Dublin, and also at Leominster, appeared in No. 5 (Third Series), of the London and Edinburgh Philosophical Magazine.