will not serve for a larger or smaller one, so that this plan is on a par with the other. There may be better plans of jointing than these, but I never heard of them. By the tool which I have invented, the length of the joint, or the thickness, will be no obstacle-the tool will accommodate any size; and by two cuts of the saw, there will be a dozen pieces or more, according to the size of the tool, already smooth and square at each end. For filing there is no occasion, as the saw does all that is required, and the joint is completed in less time, with less trouble and equal neatness. This tool may be used for cutting of lengths of wire, of all shapes and sizes, with accuracy and dispatch.

I am, Sir, yours, &c.
A GOLDSMITH'S APPRENTICE.

Description.

Fig. 1 represents the plate which the springs, AAAAA, slide into, divided the same as a rule, for the convenience of shifting the springs exactly as wanted.

Fig. 2 shows the width of the springs edgeways, and likewise the split down which the saw descends.

Fig. 3 gives a view of the springs, and also of the plate in which they are supposed to be screwed, showing the screw and nut underneath. Three of these springs are represented shut, and the other two open. The view given of the springs is a side one; that side of the springs now fronting us will be turned to the end of the plate, and the edge of the springs, as represented at figure 2, will be turned towards us. By unscrew ing the nuts, springs may be taken out, or more put in, as wanted. In setting the tool for any particular size, an allowance must be inade for what the saw reduces. There will be no difficulty in pushing the pieces out after they are cut; take some more pieces of wire and press in, and the other pieces will tumble out.

Directions to the Maker.

As the springs have nothing to press against, it will be necessary to make them strong; the chops of the springs

must be fluted for the round wire, or else the wire will shift, and the split at the top of the spring must be made.correctly straight, otherwise the tool will not answer. The split must be made so that the saw shall not move about in it, only forward and backward-the thickness of a piercing saw will be sufficient.

The flutes must also be level with each other, otherwise the wire will not find its way through. The plate may he made of a rough file, leaving the teeth underneath; and the nuts ought to be made of the same-if not, the springs will be liable to shift. Perhaps it would make a better finish to the tool, if a groove were cut underneath the plate, of the size just sufficient for the nuts to move in, and just the depth of them, so that when the springs are screwed, there shall be no appearance of either nut or screw.

PERPETUAL MOTION, AGAIN.

Let those laugh now, who never laugh'd before ;

Let those who ever laugh'd, now laugh the more..

SIR, I am aware, and therefore anticipate from you at least a laugh, upon receiving a communication on this subject; but if your risible faculties can be composed, I would then invite a few serious moments.

You will agree with me, that the universe is a display of perpetual motion, and that such a thing does, beyond all doubt, exist. The cooperation and nice combination of what or how many various causes (each perhaps governed by different laws, and opposite in their effects) which produce this perpetual motion, it might be presumptuous to endeavour to ascertain; suffice it to know, that all concur in a most wonderful manner to exhibit what man is striving to discover, and hi therto in vain,

I coincide in opinion with those who consider there are insurmountable difficulties to the discovery of perpetual motion, by any machinery wholly subservient to the laws of gravity and the mechanical powers; and as the perpetual motion of the universe is not effected under the laws of gravity only, there appears but little probability of man's disco vering it by such machinery.

By consulting Nature's laws generally, success is more likely to folwell known) agency is available for low; and, indeed, an invisible (but the purpose. I have, therefore, re

M

Description.

The above drawing represents a wheel of one foot in diameter, revolving on its centre, C. Its circumference, RRR, is a thin steel hoop, or rim, three-quarters of an inch broad, formed in the indented manner delineated, and con nected to the centre by two bars, bbbb. (The thiu edge of the rim presents itself to view.)

MMM are three magnets fixed, totally unconnected with the wheel; their poles are placed as close as possible to its rim, but not to touch it, to impede its going round. These three magnets are so disposed as alternately to exert their full attractive powers, at right angles, on the flat indented surfaces of the steel rim of the wheel; and as it moves round, the attraction of one magnet does not cease its operation until another magnet exerts its full power.

The weight of the wheel on the side next the magnets being thus continually lifted, or rendered lighter, by the attraction of the magnets, causes the weight of the opposite side of the wheel to preponderate on its centre, and the wheel to revolve, and to continue a perpetual rotatory motion-at least, as long as the magnets retain their attracting power.

By inserting the foregoing in your truly useful publication, you will oblige,

107

IMPORTANCE OF THE BAROMETER,

AS INDICATING THE APPROACH
OF HURRICANES.

In an article by Colonel Wright, inserted in our 30th Number, on the Rise and Fall of the Barometer with. in the Tropics, the writer gave many strong proofs of the advantageous use which navigators might make of the indications of this instrument, especially in those cases of violent hurricane that occur so frequently in the Indian Seas. The following corroborative remarks on the subject, we extract from an interesting letter to the Editor of the South African Chronicle :—

"Every one at all acquainted with the mechanism of a barometer, is aware that its construction originated in a discovery, that the mean density of the atmosphere is capable of supporting a column of mercury equal to about thirty inches in length; it follows, therefore, that every deviation from that height is the result of some change or other in the actual density or gravity of the atmo sphere which supports it, the trifling effect excepted which is produced by the attractive and cohesive qualities of the tube in which it is confined; but, although it is clear that no alteration can take place in the quicksilver, which is not occasioned by a proportional change in the weight of the atmosphere, these changes depend upon such a variety of causes, and are frequently so minute as not to be perceptible, or accompanied by any visible alteration of the weather, which is the reason why sinall deviations in the barometer do not always indicate any change whatever in the latter. It is a well-established fact, that the barometer undergoes little or no variation throughout the region of the tropics, except when under the influence of an approaching hurricane, when it is equally notorious that it invariably falls rapidly and considerably, as it inevitably must do, if we consider the principle upon which the quicksilver is supported in the tube, and connect it with the probable cause of these storms, which are as much exceeded in violence, as the situations in which they are generated are at most other periods in mildness, by the more boisterous climates of Europe.

"Of the danger attending them, I have acquired some degree of knowledge from dear-bought experience, and of their approach we may at all times be warned by an infallible monitor, although 1 fear it is too often fatally slighted; through ignorance, perverseness, or prejudice; because that part of the ocean to which these remarks are confined is

frequently sailed over without having to encounter a hurricane; and because, throughout such navigation, the barometer may remain almost stationary, it is too apt to be thought a useless appendage to a ship in those seas; but, so far is this from being a just conclusion, that, in my opinion, the circumstance of its not being affected by any other weather than such as is attended with imminent danger, is the strongest argument that can be adduced for its being particularly valuable in those regions. In high latitudes the experienced eye and judgment of the sailor prove a pretty correct substitute for a barometer; but the tropical hurricane, like the wolf in the fable, always comes on when least expected, so far as appearances are concerned, and therefore the barometer is the only guide to be safely confided in. My conclusion then is, after many years experience of the navigation of those seas, as well as from theory, that, whenever the barometer is observed to fall suddenly and considerably any where within the tropics, it may be considered indubitable, that an uncommon degree of rarefaction of that part of the atmosphere is in progress, and that it will inevitably be followed by a violent reaction. Not a moment, therefore, is to be lost in bringing the ship to the wind, and preparing her for a storm; from that moment the ship has passed the circumference of a circle,

the centre of which is the centre of danger, inasmuch as it is the centre of the atmospheric expansion. Among other instances, in corroboration of this argument, which have come within my own knowledge, I shall relate the particulars of two.

"After taking under review the circumstances as connected with the two particular instances I have quoted, together with the result of sonie consideration of the subject, after many years experience, I think I may fairly conclude, that the barometer will infallibly indicate the approach of a hurricane within the tropics, and that where the storm commences, there will it first subside, and there will it be most moderate and if this be the truth, one would almost think it were an instrument placed by Providence in the hands of sailors to warn them of their danger; for if they are to proceed in their course, in defiance of such warning, the barometer might as well be on shore. The sailor is an amphibious animal, and there being something peculiar in the disposition of animals which partake of a twofold nature, I recommend, in conclusion, that those gentlemen and ladies from the East, who have recourse to our salubrious climate for the purpose of repairing their shattered constitutions, should

never, but when it cannot be avoided, engage a passage in a ship that is not possessed of one, and that they should keep guard over its silent salutary warnings themselves."

NAVAL ARCHITECTURE.

SIR,-If the following remarks on the papers in page 427, volume III., and pages 30 and 50 of volume iv. of your very useful and interesting Magazine, should appear worthy of your notice, you will, by inserting them, afford pleasure to one who wishes to think correctly and liberally, and who would en deavour to enable others to think so too.

The point in dispute between the writers above referred to, seems to be, whether or not the advantages of liberal and scientific instruction may not couduce to the improvement of the intricate, and, at present, very imperfectly understood art of constructing ships?

If the question be determined in the affirmative, as it certainly must be, it would seem desirable that individuals of scientific attainments should, by some means or other, be induced to devote their time and talents to the advancement of an art of such essential importance to the welfare of the nation, since. both the acquisition and the protection of its wealth greatly depend upon it.

With this view, it is presumed, the Government determined to establish the Academy of Naval Architecture at Portsmouth; and it was, without doubt, the most eligible way of providing for the supply of that knowledge, in which we, the greatest maritime nation in the world, are shamefully deficient, compared with our neighbours, the French, and perhaps the Americans. The me thod of selecting the students for the Academy was also the most wise and liberal that could have been adopted. It was publicly advertised, that an examination for the election of students would take place; and thus an opportunity was afforded for any one who chose to offer himself as a candidate. The working apprentices of the dockyards were, and still are, permitted to enter under rather more advantageous circumstances than other individuals. The examinations, there is every reason to believe, have hitherto been conducted with the most scrupulous impartiality; the preference having been given to those who, by the superiority of their talents and attainments, merited it..

Au institutiou established on such liberal principles is an honour to the country and to the Government that maintain it; and it ill becomes such persons as Anti-Calculus and Omega to endeavour to bring such an institution, together with the founders of it, into