sion to practise the projections of the sphere, and those whom business or pleasure leads to this practice, are already, it may be fairly supposed, so far advanced in the elements of science, as not to need detailed examples of the application of the scales adapted to this particular purpose, whose use, moreover, is evident enough, in the description of their construction.

To construct the line of chords. Let A D BE, be a circle whose radius, CD, is equal to the proposed radius of the sector. Divide the quadrant, A D, into 90 degrees; and subdivide each degree by as many bisections as the magnitude of the arch will allow without confusion. Draw the chord A D, and transfer with the compasses to the chord, 4D, from the centre, A or D, the several distances, A 80, D 10, &c. Number these transferred distances according to the several numbers on the arch, from 10 to 90. The line, D 4, thus divided, is a line of chords. The double line of chords upon the sector, reaches only to 60°, for ch. 60° radius. And this extent is sufficient for the uses to which the double line of chords is applied. The first and principal use of this line is for laying off and measuring angles. Let it be required at the point, A, in the first line, A B, to make an angle o f55 degrees.

=

B

In A B, take any point P, from centre A; with radius, AP, describe a circular arch, PQ. Make the same AP, a parallel distance between 60, in the line of chords; then the parallel distance of 55°, on the same line is to be set off from P, on the arch P Q, and A Q to be joined. PAQ, is the angle required. For by property of similar triangles,

ca:ab::cp: pq, and on the other hand, ca: cp: ab::p q, where the ea is the radius of the sector; e p, chord of 55° to that radius ; and a b, the radius of the arch P Q. Where fore pq bearing the same relation to ab, that cp does to ea, is the chord 55° to that radius.

(To be Continued.)

PIRACY OF ENGRAVINGS. Some few of the more booklearned among our readers may be probably aware of the existence of a monthly publication called the "London Journal of Arts and Sciences," which is made up almost entirely of copies obtained from the Rolls office, of patents, old and new, good, bad, and indifferent, and illustrated by copies of the drawings appended to the said patents.-Nay, all the world must remember something of it; for, now that we bring the circumstance to mind, we have mentioned its name at least twice or thrice in the pages of the Mechanics' Magazine (which every body reads). Once, indeed, we actually had it in contemplation to edify our readers by giving a monthly digest of its contents; but after making a cast or two with our nets, we fished up so little for our pains that we gave up the design in despair.

It is commonly observed, that those who have the least to be vain of, are always the vainest, and the most pugnacious in the defence of the little which is theirs; and it is even so we find with the owner and getter up of the publication to which we have just alluded.-While among the editors of

all other scientific works, even those of the highest reputation for talent and originality-it has been the practice to borrow from one another, accounts of new inventions, and improvements, without any one mur muring or complaining (provided only a due acknowledgement of the obligation is made); and this, not only from a feeling of proper liberality towards one another, but from a desire (superior to every personal consideration) to see every new addition to the common treasury of knowledge made as extensively known as possible; while such is the prac tice of all our most respectable and useful journalists, the Brands, Brewsters, Jamesons, Gills, and Phillips's, of the day-the Editor of this thing of copies, called "the London Journal," for almost every letter and line of which he is indebted to that common storehouse of the public, the Patent Office-which is made up of matters that are open and free to every one-which scarcely ever contains a single original contribution of its own to the arts and sciences-this feeder on the public common (he of all others!) has recently thought fit to declare war against the general usage, and to call the laws to his aid, to harass and punish every one who innnocently confiding in that usage, may have made the slightest use of the few of his copies that are worth recopying. The first appearance of Mr. Newton in the courts (if we recollectright) was as an applicant to the Vice Chancellor for an injunction against some one who had published an account of a new patent, with drawings so like those in Mr. New ton's Journal, (pity that a name so -illustrious in science should ever be seen in hostility to its interests) that there seemed every reason to believe they were made from his copies, and not from the originals in the Rolls office. His Honour, however, scouted the idea of any one establishing a copy-right in drawings that were the common property of the public, and refused the injunction.-Noways abashed by this reproof from the second highest legal authority in the country, Mr. Newton resolved to_try what an action at common

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law could do for him; and in this, we regret to say, he has so far succeeded as to obtain, the other day, a verdict of damages (against the publishers of the Register of Arts and Sciences) for the same sort of transgression which the Vice Chan cellor refused to recognize as furnishing any ground for his equitable interference. We have heard, too, of other actions having been instituted and compromised, under the terror of the verdict thus obtained.

We have no intention of entering here into a discussion of the question of legal right which Mr. Newton's proceedings involve. Possibly the Vice Chancellor may have been in error, and the court of common law in the right. Strict justice may require that a copy of an engraving by one man (even though a copy) shall not be copied at second hand by another. Considering, however, that any person by going a few doors farther down Chancery Lane than Mr. Newton's shop, could obtain a copy of the same engraving from the original drawing, and make what use of it he pleased, without Mr. Newton or any one be ing entitled to call him to an ac count, we must be allowed to give it as our opinion, that there is no coin of so small a denomination which would not more than a thousand times repay Mr. Newton for any damage of which such a case fairly admits.

Our business, however, is not with the law, but with the decencies of the case. Let it be granted that Mr. Newton, or any other publisher of accounts of new inventions, whether in the first or second instance has a right to inflict the prodigious injury of a lawsuit (for be the damages however small, the expenses are always enormous and the same) upon any one who copies from him; it is such a right as we make bold to say not many other persons besides Mr. Newton would have thought or ever think of enforcing. It is a right not only oppressive towards the luckless offenders, but one which, if generally put in force, would be most injurious to the progress of knowledge, and of course to the interests of every individual

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of the community. Injurious to inventors, to whom it is of the greatest importance to have their inventions published every where, in order that they may reap without delay the largest possible benefit from them; injurious to all men engaged in scientific inquiry and improvement, whose researches may be materially aided by early information of what others have done or are doing; and injurious to the public, which is more or less benefited in proportion as the channels by which information is conveyed to it are untrammelled and free. To nobody, in short, but to some one who prefers a paltry gain to all other interests, can it be of advantage, thus to make a preserve for himself, of what should be borne on the wings of the winds to every part of the earth. We are not even sure that it will, in the long run, be of advantage to such a would-be-exclusive; for there is a possible consequence of such conduct as Mr. Newton's, which we suspect he has not taken into account. The few readers of his "journal" are chiefly of the scientific and inventive class; it depends upon this class, in fact, for its very existence. We have reason, too, to know that in many instances Mr. Newton has been saved the expense of procuring copies from the Patent office, by soliciting and obtaining from patentees the loan of their original drafts and drawings. But does Mr. Newton suppose that in ventors and men of science will continue to patronize a publication which opposes itself so flagrantly to their interests? Does he imagine that patentees will step willingly into his patent-trap, when apprised, as they now are, that if once caught in it, they may chance to be held fast there for ever? Has Mr. New ton reflected sufficiently how men may be affected by the conviction, that to have an account of a new invention first inserted in his "jour nal," is a sure way to deter every other journalist from giving it publicity, lest Mr. Newton should fasten on him an action for piracy and damages?

they seem to us to deserve, we are actuated solely by a regard for the public interests which they involve. We have neither private purpose to serve, nor personal resentment to gratify. We owe the man neither grudge nor obligation. Nor is there any journal which is less likely to be affected by such conduct than the Mechanics' Magazine. For, thanks to an extensive correspondence with ingenious men, there is none which depends so much on its own resources, and so little on the aid of its contemporaries. We have rarely been without an abundance of original drawings in store, and but for the propriety of occasionally making our readers acquainted with what is published elsewhere, we need never have borrowed from any one. When we have made free, however, with the works of others, it has been without hesitation or fear; for it was under the implied understanding that others would use equal liberty with ours in return, and in the fullest confidence that though the case were otherwise, nobody would grudge a leaf to the cause of scientific instruction (we did not then even except Mr. Newton). Neither do we meditate any cessation from this practice; we shall still place our trust in the same understanding and confidence, and continue to gather from all sources matter for the. instruction_and_amusement of our readers. From Mr. Newton's Journal alone we shall henceforth extract nothing. Warned by the fate of our contemporary, and resolved, at the same time, that our readers shall be no losers by the event, we shall carry our panniers to the same common from which Mr. Newton is himself supplied; and if other scientific journalists will only do the same, Mr. Newton may be left withont apprehension or concern, to the enjoyment of all the friends, patrons, and readers, whom his exclusive and illiberal pretensions shall have left him.

Communications (post paid) to be addressed to the Editor, at the Publishers', KNIGHT and LACEY, 55, Paternoster Row, London.

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PLAN FOR THB ADDITION OF A

What advantage has Mr. Vallance's

TION TO A WATER-WHEEL.

[Two other plans for this purpose have been received, and will be afterwards inserted.-EDIT.]

Sir,-On sitting down to give an answer to J. S.'s query, in p. 80 of your 180th No. I cannot refrain from expressing to my fellow readers the mutual advantage which might be derived from your amusing Magazine, would they more frequently contribute replies to the many practical questions which weekly nake their appearance in your pages.

Though many ways might be devised to produce the effect required by J. S. I think the following is perhaps as simple as the case will allow. I shall suppose the cocks to be turned every half hour, and the waterwheel to make four revolutions in a minute. Let a, be a spindle, connected directly with the axis of the water-wheel, on which is cut a single-threaded screw, b, which works in the teeth of wheel c, of 240 teeth, causing it to revolve once in an hour; on the rim of this wheel is fixed a pin, d, at a short distance from each side of the wheel, two pins, f, f, are fixed in the framing which carries the wheel, c; on these hang the cranks, g, h, so situated that the pin, d, in passing moves them from their present situation to that shewn by the dotted lines, which motion is communicated to the cocks by means

of the connecting rods, i, and k, and the bell crank, i. The cranks, g, and h, are connected by the rod, m, so that the motion of the one, h, puts the crank, g, into the proper situation to be struck by the pin, and vice versa; also when the crank, g, is struck, it communicates its motion to the cocks. Fig. 2, shows how the connecting rod, k, shuts one cock at the time it opens the other.

I am, Sir,

Your sincere well-wisher,

J. F. E.

P. S. Vallance's New Mode of Conveyance. I cannot lose this opportunity of mentioning an idea which just occurs to me, (which is new at least,) with regard to Mr. Vallance's mode of conveyance.

2

Newcastle, viz. Drawing carriages on a railway by means of ropes wound up by stationary steam engines? It appears to me that Mr. Vallance has gone the most round about way possible to obtain exactly the same effect; for instead of drawing by a rope of hemp, he builds an immense tunnel that he may draw his carriages by a rope of air! I have no doubt whatever, that the power expended in working Mr. Vallance's air-pumps would have much greater effect at the end of a rope, or even applied as a locomotive steam engine. Must not his pumps work twice as fast to double the speed of his carriage, and would not that require twice the steam power? The same as to increasing the weight. I have arrived at the end of both time and paper, or I could mention many circumstances which confirm the truth of my opinion, which I will probably bring forward at another opportunity; in the mean time I should be glad to know the opinion of some of your correspondents.

J. F. E.

DIFFUSION OF USEFUL KNOWLEDGE. A pamphlet which has been just published, entituled, " A Discourse of the Objects, Advantages, and Pleasures of Science," and which is generally ascribed to the pen of public notice, the formation of "A Mr. Brougham, has ushered into Society for the Diffusion of Useful Knowledge." It ranks among its leading members a number of very eminent and justly-respected individuals: Lord Auckland, Lord Suffield, Lord Althorpe, Lord John Russell, Sir James Macintosh, Sir Henry Parnell, Bart., John Smith, Esq. M.P., Hon. J. Abercromby, M.P., T. Spring Rice, Esq. M.P., J. F. Buxton, Esq. M.P., Dr. Lushington, Mr. Denman, Mr. Wm. Albesides Mr. Brougham himself, who len, Dr. Olinthus Gregory, &c. &c. may, we presume, be considered as the master-spirit of the association.

8vo. pp. 48, price 6d. Baldwin Cradock, and Joy.