BARON DE BODE'S PATENT CABLE

RETARDER AND STOPPER.

Sir, I herewith forward you a drawing and description of this most useful nautical invention of the Baron de Bode's. I feel confident that your maritime readers will pronounce it to be the best method that has yet been devised for stopping or retarding a cable, which it has already been declared to be, by firstrate authorities upon such subjects.

seen;

The

The cable stopper consists of an iron bed a a, with upright side pieces bc, supporting two friction-rollers d d; the side piece c, is higher and stronger than b, and the short lever e, carrying the friction roller f, is connected to the handspike on lever g by a strong axis or pivot, through the side piece c. action of the apparatus will be readily the lever g being raised, the friction roller f will be above, and clear of the cable; as soon as it is desired to retard the chain, depress the lever g, when the cable will be clasped between the rollers f and d d; and by further depressing the lever g, so as to bring the roller f to a nearly centrical position, the chain will be stopped by being clutched between the roller and a stud or elevation in the bottom of the stopper.

The following are amongst the advantages stated by the Baron to be consequent upon the use of his stopper :

Most stoppers have not the means of retarding the speed of a running cable which is known to be so pernicious to the men, and articles on deck, and those which can partially retard, can only do it at the destructive expense of both the cable and the stopper, as the cable has to rub through fixed bodies of metal; whereas, in the Baron's it slides between rollers.

The cable being stretched whilst running, when the speed is retarded by pressing the middle roller on it, there is no risk of destructive chafing, as it never gets in contact with the small elevation on the bottom of the stopper, until the middle roller is pressed down to the degree of stopping the cable altogether.

All stoppers hitherto in use stop the cable by pressing suddenly on one link only of the chain, whilst the roller of this one, presenting a larger surface, presses on three links; and instead of stopping the cable suddenly, can but stop it gradually, however quickly the

operation may be performed. This must naturally prevent many ruptures, and even the frequent partial injuries to which cables are so subject.

This stopper will answer for a hemp cable as well as any chain of whatever size or figure it may be ; whilst the other stoppers in use are still more destructive to hemp cables than to chains.

As the cable never has to force its way through two fixed metal bodies, there is no reason for either stopper or cables wearing out by the operation of stopping.

Most stoppers are by their angular opposition to the strain of the cable, and by their being fixed only to one of the ship's beams, more or less exposed to be broken or torn from their holdings, or even to injure the beam they are attached to; whilst this one, presenting a large basis may easily be fixed to three or more beams, by the means of two cross beams underneath the deck; and as it works quite horizontally, it cannot be exposed to capsize, nor to be torn to pieces.

The construction being much simpler and more solid than all others, it is evident, that besides its not being so exposed to the above accidents, it must in itself be less subject to repairs.

I am, Sir, your obedient servant,
HAWSER.

March, 1838.

MIXTURE OF SULPHATE OF BARYTES WITH WHITE LEAD.

Sir, In reply to your correspondent, who inquires whether sulphate of barytes is a fit and proper ingredient to be mixed with white lead for paint, I beg leave to say, decidedly it is not; and its effects I have found to be these: in painting which is exposed to the weather, such as greenhouse lights, &c., it eats up (if I may be allowed the expression) the oil with which it has been mixed, and remains on the surface in the form of a white powder, which may be wiped off as readily as common whitewash, In in. doors painting, such as staircase walls, &c., which are intended to be left glossy, it causes the work to have a streaky appearance, very similar to what would be produced by a wet, dirty cloth being passed over its surface, which very frequently brings the innocent workman into disgrace. I am not aware that there

OBJECTIONS TO DAVENPORT'S ELECTRO-MAGNETIC ENGINE.

Sir,-In Number 763 of the Mechanics' Magazine, I observe a long communication from Mr. Oxley, in support of a calculation which he made in a former number, of the power of Davenport's electro-magnetic engine. I do not intend to enter on the merits of that calculation as such, but I contend that its principle is entirely erroneous. The wheel of the engine revolves by the attraction and repulsion of magnets; now, if the electro-magnet received its attractive power the instant that its wires were in the galvanic circuit, it is plain that there could be no assignable limit to the velocity of the wheel, and consequently that the power of the engine would also be unlimited. It has, however, been sufficiently demonstrated that magnetism cannot be induced instantaneously, and therefore the magnets can only attain a certain limited velocity, say 10 feet per second. It is plain, that if the circumference of the wheel revolves at a rate thus defined, no increase of power whatever will arise from the increase of the diameter of that wheel-its power will depend entirely on the size of the magnets.

This consideration makes me not quite so sanguine as Mr. Oxley of the success of the engine which is generally, I don't know how fairly, put to Mr. Davenport's credit; but nil desparandum, the landmark which I have pointed out, will, without doubt, by improvements in the construction of the electro-magnets, and in the generating of electricity, be obtained in such measure, that electromagnetism will eventually supersede steam altogether.

Yours respectfully,

Manchester, May 15, 1838.

F.

ON THE CONSTRUCTION OF IRON SUSPENSION BRIDGES AND CHAIN PIERS -BY MR. JAMES DREDGE.

Sir,-In hopes of your favouring me again with a place in your valuable Magazine, for the communication of my ideas on the construction of iron bridges and chain piers, I repeat the liberty of addressing you on the subject. In my former letter I told you, that if they were mathematically constructed more strength would be obtained at one-fourth the usual cost, I will now furnish you with my explanation, that your readers may have an apportunity of duly estimating the economy, utility and importance of the principle I have advanced.

The material in the arch of all bridges, is in a position of reduced power; therefore, arrangement and gravity ought to correspond; every advantage should be embraced for relieving the vertex of the arch, or ends of the levers, because requisite diminution of material toward the extremity of the lever is increase of power. This truth is clearly exemplified in the horizontal limb of the oak, the fishing-rod, and the ship's mast; these, as well as bridges, and the strength of all bodies, are obedient to the same law.

Every part of a bridge mathematically constructed, is active and powerful, and that in proportion to the strength of its materials, bulk, and versed sine. Gravity is borne by the arch commencing at the vertex or point of inflection, and progressively increasing from thence to their bases respectively, with power increasing in the same ratio; and horizontal pressure or tension is sustained by the roadway, which renders it uniformly stiff and powerful; but on the other hand, as they have hitherto been constructed, especially suspension bridges, the chains, or suspended levers, are parallel from their fulcrums throughout; half of the whole suspended weight being concentrated on the point of inflection, or centre of the bridge, and is oppressive in proportion to the deflection of the chains; the roadway is destitute of horizontal pressure or tension, therefore it is undulatory, notwithstanding two or three extra layers of thick planking, and heavy trussing are had recourse to.

In short, the section of the entire chains for a span similar to the Ham

mersmith Bridge, on my improved taper principle would not exceed 40 square inches at each base, and 6 square inches at the centre, which would only average 23 square inches, instead of 180,-as it now is; and for the Clifton Suspension Bridge, 70 square inches at each base, and ten at the centre, instead of 496 square inches at each base, and 458 at the centre, as proposed by Mr. Brunel, and adopted for execution.*

In corroboration of what I have stated, I have given proof by experiment before various parties, and in particular before a numerous assembly of the most influential gentlemen of Bristol and the neighbourhood, for the results of which, I must refer your readers to my last letter. Independent of all I have said, a bridge in Bath of 150 feet span is constructed on my patent principle, which demonstrates its truth better than words.

I am, Sir, your obedient servant,
JAMES DREDGE.

P.S. My patent chain is well adapted for portable bridges for military purposes, and for spans of ten times the magnitude yet accomplished, and for sustaining a greater weight than ever was yet on any bridge.

J. D.

THE NEW LAW OF COPYRIGHT.

Mr. Serjeant Talfourd's New Copyright Bill has passed the second reading by a majority of fifty-two, and the measure may therefore be considered safe, so far, at least, as the House of Commons is concerned. Notwithstanding, however, the triumphant manner in which it has thus passed through the fiery ordeal, it may be doubted whether its success is attributable so much to the cogency of the arguments which its supporters brought forward in its favour, as to a certain chivalrous feeling to which the House seems to have been roused, by the eloquent speeches of the introducer of the measure, backed by the published letters of Wordsworth, Southey, and others of the irritable genus, in the same high-flown strain. Certain it is, at any rate, that inost of the reasons advanced by the advocates of the bill are

* See Drewey's Memoir on Suspension Bridges.

anything but convincing to those not predisposed towards it, that many of them, tell quite as much against as for the bill, and many more are absolutely convertible into excellent reasons for the opposite party!

Thus, Lord Mahon held forth in the most pathetic strain on the degradation of Dryden in being forced to pander to the vile taste of his age, instead of following the dictates of his own genius,— an evil which the wonder-working new bill is of course to rectify. But how? If an extended term of copyright could have effected the object, Dryden would never have suffered degradation, for in his time the term of copyright was, not for sixty-years only, but perpetual; and according to the theories now laid down, he ought to have been occupied in standard works alone, and not to have dreamt of ministering to the passing tastes of the day! If, in the time of Charles the Second copyright had only been allowed for a few years, or not at all, the case of Dryden might have been brought forward with some effect; but it is certainly rather strange that it should be adduced in support of a bill introduced as a sort of partial restoration of the extensive" common law right" under whose operation glorious John" was the willing slave of the titled debauchees of his day. If the extent of the term of copyright he admitted to have anything to do with it, it would surely be better to shorten rather than lengthen it, since, under the present twenty-eight year system we have no author so 66 degraded" as poor Dryden was, in the full enjoyment of all the advantages of "perpetual" copyright.

This unhappy instance speaks volumes also, especially in conjunction with others also adduced by supporters of the bill, as to the effect it may be expected to have in stimulating the production of works of a standard order. It has been seen that Dryden, in spite of every imaginable legal "protection" for his labours, spent his energies in ephemeral productions; and Southey, we are told, has received more for his contributions to periodicals, and other temporary matter, than for all his larger works. If, therefore, as the billites constantly take it for granted, the great inspirer of literary genius is the hope of profit, what expectations can we indulge in

under the bill? None, certainly, than that ephemeral productions will be at least as rife as ever. In the face of such facts the notion that the proposed extension of the term will encourage soli dity in literature, must be given up at

once.

The notion alluded to, that gain is, and must be the great inspirer of the highest efforts in authorship, is a favourite one with the learned serjeant and his followers, one of whom actually went so far as to assert, that the majority of our standard works had been produced by writers for their "daily bread." At this rate, we are to believe that Milton wrote "Paradise Lost" for the sake of the ten or fifteen pounds he received for the (perpetual) copyright,-that the illustrious Bacon, composed his "Essays" with a keen eye to the main chances, and that Locke produced bis immortal "Treatise on the Human Understanding" from no higher motive than that which actuated the printer who set up the types! The speaker who broached the idea would, however, probably draw the facts to support it from the literary history of the last century, and rely on the names of Johnson, Goldsmith, and their contemporaries, to bear him out. But what then? These, authors wrote at a time when only the fourteen years' copyright was in existence! The argument therefore would better apply, as in the former case, to a reduction in the length of the exclusive privilege, instead of an increase.

The speakers for the measure were very anxious to draw a distinction between the case of patents and of literary copyrights. It may be admitted that there are some points of difference between the two, but that they resemble each other in the main features is no less unquestionable. A perpetual monopoly, in either case, is not to be thought of. The public interest requires that the works of the author, as of the inventor, shall be thrown open to the enjoyment of all,-of course not without a due recompense. As to determine the measure of this recompense would be a difficult task, as it is not practicable to set up a tribunal to judge of new performances, and, if meritorious, to reward, or, if not, to reject them,-the alternative is adopted of leaving the author, like the inventor, to bring forward his

production as he pleases, and of making his recompense depend on the public opinion of his merits, by granting him a monopoly for twenty-eight years, or just double the ordinary one of an inventor. Yet authors, we are told, are not sufficiently" protected," and one of the members of the honourable house actually called upon his colleagues in the name of common justice to grant that protection to literary men which the law did not refuse to 66 an Arkwright"! To judge from this gentleman's speech and others of the same class, it might be supposed that at present there was no copyright law at all, and it would hardly be suspected that the privileges granted to authors were so superior, in every respect, to those charity doled out to patentees on payment of exorbitant fees.

The strangest misapprehensions seem indeed to prevail generally as to this question. One of the strangest is that the only parties interested are the authors and the booksellers-and that if the bill be thrown out, the former will suffer, that the latter may be enriched by the fruit of their labours. The third party, whose interests are not the least among those concerned,-the public,-is generally quite lost sight of. Thus it has been said, in reference to the oftenquoted case of Wordsworth, that the question is, whether the heirs of the poet shall enjoy the profit of his works, or the heirs of Mr. Tegg (the bookseller who is so active in opposition to the bill.) But it is no such thing. Under the present law, at Mr. Wordsworth's death, and the consequent expiration of the copyright in his works, they would become the property, not of this or of that man's heirs, but of "all England," -of the public at large. If Mr. Tegg or his heirs reap any profit, it will only be by the exercise of their callings,—and Mr. Wordsworth's heirs will have just the same privilege. The notion that the title of the cause now pending is only "Authorv. Bookseller," has been worked upon to such an extent, that it would almost seem that the advocates of the bill see the importance of mystifying the public on the subject, and preventing the names of the real defendants from being seen. In order to do this, all the old stale stories of the poverty of authors, and the luxury of booksellers have been revived, and the bill held out as the

means of reversing the picture. How it is to effect this is not indeed very perceptible, unless it were accompanied by another having for its object to compel authors to be prudent and provident. But meanwhile the very intention serves as a good stalking-horse, under which to cover the institution of a monopoly which, undisguised, would be intolerable. It is singular enough that in the midst of the denunciations of the rapacity of booksellers, and their hard treatment of authors, the case of Sir Walter Scott is continually being referred to as proving the necessity of "turning the tables" on the publishers; that case being one in which an author made immense gains by his literary exertions, only to lose them by dabbling in the lucrative business of publishing! Surely this often-adduced case of the author of Waverley, is the worst that could have been selected, in all points, to prove the necessity of the bill; especially when the immense profits of the trade which ruined him, are to be compared with the inadequate remuneration afforded by the existing law to the trade" (as it seems to be considered) by which he made his fortune!

It is to be hoped that, notwithstanding the progress the bill has already made, it will receive very considerable modifications before it becomes law, or otherwise the public will probably be the greatest loser, and neither authors nor publishers the gainers. As the principle of extending the present law may now be considered as adopted, it might perhaps be as well if the adverse party turned their attention to the mak.. ing of the extension as small as possible; every year added, is an evident disadvantage to the public, while it is by no means so clear that it will be an advantage to any party. The pretence that the production of more solid works than the great bulk of those now published,the only boon held out to the public for the great deprivation they are to suffer,is evidently untenable, for reasons before stated, as well as innumerable others. Our standard historians, for instance, required no century of monopoly ; Hume, Gibbon, and Robertson wrote under the fourteen years' system, while the tribe of light and frivolous authors whose discouragement is one professed object of the

bill, have flourished since the term has been extended to " twenty-eight years at least." To lengthen the term to sixty years after the death of the author, then, will obviously be no remedy for the complaint, while the postponement of the time at which the really standard productions of recent times are to be thrown open to the public will be an undoubted and considerable evil. The very case of Wordsworth, to meet which would appear to have been Serjeant Talfourd's chief object in undertaking his bill at all, speaks trumpet-tongued to the fact that it will have no effect in improving the tone of our literature. That Wordsworth must have written for something else than the money produced by copyright, is evident from the statement made by the friends of the bill, that his poems had produced him more within the last year or two, than they ever had done during the first thirty years of their publication. He must have continued writing, therefore, from some other impulse than a pecuniary one; and is even now likely enough to make more money by his office of stamp distributor, than by his poetical works, even when the term of monopoly shall have been enlarged. Nevertheless, the case of his slow-growing popularity (a singular one, by the way) must be admitted to prove that the present term may be too short, in some instances, to secure due remuneration to the author, on the principle that the public are to be the judges of the extent of that remuneration. It does not follow, however, that so enormous a term as that of sixty years after the death of the author should be adopted ;—an absolute term of forty years from publication would surely answer every purpose, and at the same time not deprive the public of all hope of seeing a new work added to the general stock before it became quite out of date. It may be objected that an author, under this arrangement, would often outlive the copyright of his work; but wherein consists the force of this objection? Parliament has been called upon to extend the same protection to an author as to an inventor; and what hardship is it considered that the patentee should outlive his patent?