ing fixed to the shaft) and hang a sufficient weight to that lever, shall I not make the carriage advance? Does he merely mean to prove that wheels of a given diameter are necessary to pass over certain obstacles? Suppose the wheels to have teeth working in other teeth on the plane upon which they are to move. If I were to press upon the spoke parallel to the road, I should make the carriage move forwards. I should be employing a lever of the second order; my hand would be the power, the carriage the resistance, and the tooth in gear on the road the fulcrum. If I were to stand upon the spoke, and my weight were sufficient, the same result must follow. The friction of ordinary wheels. upon the road presents a resistance, or fulcrum, analogous to the teeth in the former instance. It is, by the bye, one of Saxula's confusions to call the obstacle the fulcrum; whereas, the wheel is resting upon the road when it endeavours to surmount that obstacle. Where can we find any resistance which will prevent the wheel from turning on its own axis, or in its bearings on the carriage, unless it be upon the road? Long cranks would be beneficial, if they could be used, in this way; the engine would not have to pass its centres so often in a given time, and, consequently, the power would be longer in action without a check. In stationary engines, the fly wheel carries them over their centres; in locomotion, the momentum of the carriage acts the same part. But where the speed is diminished, in ascending a hill for instance, this assistance to the engine must be materially diminished. But, after all, it seems scarcely possible to have longstroke engines in locomotive carriages, the connecting rod being necessarily so short; and as to oscillating cylinders, especially to the extent necessary, I imagine they would be too objectionable for practice. I should wish to take the opportunity of touching upon locomotive carriages intended to be worked on turnpike roads. The difficulties they have to contend with appear to me to be of two kinds: 1st. the ordinary obstacles in the roads, such as stones and ruts, &c. 2ndly. Hills to be ascended, where the resistance of the carriage itself is so much increased, that the fiction of the wheels on the ground is unable to overcome it, or the speed is greatly reduced, the momentum lost, and the engine unable to struggle over its centres. In the first case, the only remedy appears to be high wheels. The objection to these is, that the carriage must be raised so high that the risk of being overturned would be greatly increased. It might be possible to have bent arms or shafts, so that the weight might be still kept near the ground, and a toothed wheel upon the crank shaft might work into another wheel fixed to the carriage wheel. But, then, how could such a carriage turn a corner at right angles for instance? And yet, how can they hope to get on, unless the road be almost as smooth and level as a railway? What is to be done where fresh gravel has been laid down? The second case seems to have attracted most attention. The only alternative here seems to be, to have very broad wheels. Would it be possible to throw into gear on a hill or roller? This would increase the draught, and make a large additional demand upon the engine. Then, as to the loss of momentum, I be lieve all locomotive carriages have two engines, one on each side. Do these act independently, or upon the same shaft? I suppose the latter. Are the cranks at right angles to one another, so that one of them shall have the power of the engine upon it, whilst the other is passing its centre? I confess this sort of locomotion seems to me rather a hopeless speculation. Yours, &c. Νου, 2, 1831. P. T. MR. BABBAGE VERSUS MR. MOHL. 1 Sir, Mr. Mohl will have to apologise to Mr. Babbage. No nation, no individual, has ever denied the truth of Mr. Canning's sublime and beautiful praise-"The English mechanics have created another element." It was not to deny this universally-ac knowledged debt of gratitude, that Mr. Babbage dated his paper, from the opening of the Liverpool and Manchester railway. Since the publication of Mr. Mohl's reply to Mr. Babbage, the iron and coal masters have presented a memorial, in which those gentlemen declare, without NOTES WORTH NOTICE. any reference to Mr. Mohl's "pure air and bright sky of sublime analysis," that science, has, in one of its most important divisions, declined in England. Holland is a great commercial nation in Europe, Asia, and America. Permit me, Sir, through the medium of your Year 1819, was-62 × 15·0725=934.5 Then Mr. Mohl, as a Dutch moneybroker, actually purehases, in the English market, a pound of gold, for about .9135 pound of silver less than his great, great, great grandfather, could have purchased it for in the year 1601, two hundred and thirty years since. You will come forward immediately, no doubt, to acknowledge to Mr. Babbage, that science has, most unaccountably declined in England, in that division which your countrymen have ever considered the all-important. You may add, that this decline was most unintentional (which daubs us with rouge), for it was intended in 1819, that the formula should be 66×15.0725. The French, in the opinion of Mr. Mohl, are most practical mathematicians -though they have taught the calculating Dutch de faire des x. Mr. Mohl will be astonished to learn, officially, from The Times of the 9th of this month, that England, the most commercial nation, will presently be, as Holland is, indebted to France for commercial science! De faire des x; or, as Lord Brougham has translated the soul of the expression, "to learn how to reckon ten upon our fingers," was naturally the most popular phrase throughout France, when the Ecole Normale established the decimal, or, in scientific orthography, deci-mil system. Of this system, which has been so extremely profitable to commercial Holland, Mr. Mohl has not one word to address to commercial England; while of the integral calculus, which is entailed upon the mathematical aristocracy-so anxious is Mr. Mohl to instruct the people of England in this useful (?) knowledge that he has gratuitously as 127 sumed the functious of Le Ministre des Affaires Etrangeres, a la Haye.. Yours, &c. November 13. T. P.S.-Mr. Mohl says (parenthetically) that the Ecole Normale were so revolutionary as to turn the dead languages out of France, centuries after Latin had been turned out of Rome, the head quarters of the Latin church, and while the English Colonel Barrè was translating Latin for the benefit of certain English country gentlemen. The Ecole Normale thought that the peaceable sciences and the heroical, very chivalrous, and most imposing dead languages, would never grow in the same field. The dead will not converse with the living. Mr. Mohl will read the result, in the comparison of the two revolutions. NOTES WORTH NOTICE. T. "Length is not strength. A cable a yard long will bear as many tons, as the single strings of which it is composed will ounces, though they will stretch a thousand times as far." New Earth-Boring Apparatus.-A speculator of Brussels, named Jobard, has announced that he has brought to perfection a machine for boring the earth to an indefinite depth, and through any soil whatever. He has as yet, however, penetrated no deeper than 75 feet, although he asserts, that the Chinese, with inferior machines, have gone to a depth of 2,800 feet, and that through solid rock. According to this gentleman, by the aid of his invention we shall soon be as well acquainted with the centre of the earth as with the surface. We fear, however, it will be some time first. Scientific Preparations for next Year. -The founders of the Scientific Meeting at York, from which sprung the British Association for the Promotion of Science, are certainly not obnoxious to the charge of inactivity. They have already organ. ized the meeting for next year, which is to take place at Oxford; a branch committee is to be formed at Calcutta, under the superintendence of the Chief Secretary of Government, (George Swinton, Esq.); sub-committees and local committees are in progress; measures are being taken for publishing the transactions of the Association; while reports are being prepared (we suppose to be ready next year) en Astronomy, by Professor Airy; on Optics, by Dr. Brewster, (now, it is understood, a Knight of the Guelphic Order); on Meteorology, by Mr. Forbes; on Mineralogy, by Professor Whewell; and on Chemistry, by Mr. Johnston. Printing at Madagascar.-A printingpress has been introduced at Tananarivo, the capital of Madagascar, by the Missionaries, who are actively engaged in printing a translation of the Bible into the Malagassee language. Four of the natives are sufficiently versed in the business to act as compositors, while the press-work is executed by two more, and several others aid in correcting the press. Steam Communication with India.-A new plan of steam communication between India and Europe has been started. It is proposed to navigate the Rivers Tigris and Euphrates, instead of the Red Sea. The Pacha of Bagdad approves so highly of the plan, that he proposes to cut a canal between the two rivers. The advantages of this route are, that the overland journey would occupy only two days, while that across the isthmus of Suez takes five; that the sea-voyage is lessened ten or fifteen days; and the passage by the river is much pleasanter and calmer than by the Red Sea; and, which is of the utmost importance, that an abundance of fuel can be obtained at a small expense at Bagdad and other places. It is to be hoped that the scheme will succeed, which it promises fair to do. Curious Coincidence.-The Thunderer, which was launched at Woolwich some weeks ago in the presence of their Majesties, was said to be built on the principle of an invention of Sir Robert Seppings, the Surveyor to the Navy, one of the chief features being the arrangement of the timbers of the bow of the vessel in the form of an arch. Now, we recollect reading a description of an invention by a Mr. Redmund, patentee, we believe, of a rising-hinge, part of which consisted in this very improvement! Which is the real Simon Pure-Sir Robert or the hingemaker? If the latter, let the laurels be placed on the right owner's brow. Transatlantic Useful Publications.— Our readers, or most of them, are doubtless aware, that an American edition of the Mechanics' Magazine is regularly issued at Boston. Besides this, however, another work on the same plan, but edited by an American, is also published in that city, with the title of "The Mechanics' Magazine, and Journal of Public Internal Improvements;" and this, we believe, fills the place of a former journal of the same form and spirit. The first volume has been completed, and is illustrated with a tolerable proportion of wood-engravings; but it appears that the encourage> ment hitherto received by the EditorMr. Samuel N. Dickinson-has not been of sufficient extent to hold out any very bright prospects of the future. Several periodicals of the same description have, at intervals, appeared at New York, with varying success; and another, the Franklin Journal, edited by Dr. Jones, of Philadelphia, has appeared for many years with steady success. It is to be hoped none of them forget to think of their English parent with a proper feeling of gratitude. F. H. Billiard Tables.-C. R. W. will be obliged to any person who can inform him of the exact weight of Sharpe, Roberts, and Co.'s cast-iron billiard-table, now exhibiting at the National Repository, Charing Cross. Squaring the Circle.-P. L. P. is, in common with many others, quite mistaken in supposing that any reward has been offered by Government for squaring the circle. If he will look through our previous volumes, he will find abundant information as to the conditions of the problem. Hydraulic Cider-Presses." I think the press proposed by A. F. T., No. 430, ingenious; but I think there must be a valve wanting, to prevent the return of the water from the main cylinder. Perhaps A. F. T. will explain this."-L. INTERIM NOTICES. Back Volumes-Among the advertisements on the cover of our last monthly part, there was one inadvertently admitted which stated that copies of Volume X of the Mechanics' Magazine, which had been for some time "out of print," might now be had on application to any one of several respectable booksellers therein named. In consequence of numerous complaints having been made to us, of the volume so supplied being imperfect-wanting generally both Preface and Index-it is necessary to state, that the advertisement in question did not emanate from this office, and that we are in no way responsible for the honesty of its representations. We must also add, that it is not true that either Volume X. or any of the back volumes have ever been "out of print;" though certainly out of the market. All the Numbers since the commencement have been stereotyped, but the right to print from No. 1 to No. 306 inclusive, is the subject of a suit in Chancery, still unfortunately undecided. Any of the Numbers subsequent to No. 306, may be immediately had on application at this Office. The paper alluded to by E. V. R. has been all along intended for insertion, and will appear as soon as we can spare room for it. We shall attend to Mr. Wiseley's letter next week. The packets will be forwarded to E. H. through the new channel he mentions. The matter about which Querist writes to us, is one on which, for reasons that must be obvious to him, we can offer no opinion. Communications received from G. S.-Mr. Beckford-Mr. Baddeley-F. O. Y.-Mr. HopkinsonMr. Ettrick-and A Constant Reader at Windsor. 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. EXPERIMENTS BY THE FRANKLIN INSTITUTE OF PENNSYLVANIA TO ASCERTAIN THE VALUE OF WATER AS A MOVING POWER. The importance of accurate knowledge in relation to the effect of water as a moving power, and the defective state of information upon that subject, induced the Franklin Institute, in the spring of 1829, to determine that a series of experiments should be made, under its direction, upon the force of water applied to wheels; the experiments to be in detail, and upon a scale calculated to give confidence in the practical nature of their results. A call was to be made upon the members, and upon that portion of the public interested in the proposed researches, for aid, to enable the Institute to effect the object in view. To obtain this aid, and execute the necessary experiments, a committee was appointed, consisting of fourteen members of the Institute. The appeal of the Institute to the liberality of its patrons, was readily answered, and the subscription lists of the committee soon contained an amount subscribed, sufficient to warrant them in proceeding with the execution of the task entrusted to them. A First Report on the experiments which have been accordingly instituted by the Committee has been recently made to the Institute, and a copy of that Report we now hasten to extract for the information of the English public, from the last number of the Journal of the Institute. FIRST REPORT. There is perhaps no subject connected with the extensive branch of mechanics, for which theory has done so little, as for that which considers the effect of water upon wheels; the different theories advanced are at variance with each other, and with practice, so that the candid theorist confesses that the circumstances, attending the action, are of so complicated a nature as to baffle his powers of investigation. Experiment, then, can alone guide to results worthy of confidence. The experimental inquiries, in relation to water-wheels, which have, deservedly, attracted most attention, are Young's Analysis, or Gregory's Mechanics, vol. i., and vol. iii, American Philosophical Transactions. those of Smeaton.* The means of a single individual could not be competent to prosecute such a subject upon the scale required to make the results entirely practical, and we find the ingenuity of Smeaton labouring against the difficulties incident to the contracted dimensions of the apparatus which he was obliged to employ, and arranging with great skill and resource the best means to render serviceable the working models which were used in his experiments. The experiments of Bossut, which rank next in extent to those of Smeaton, were comparatively few, and were principally made upon the undershot wheel. It would not be profitable to enumerate the isolated experiments made in different countries upon this subject, since the sum of the information which they convey is extremely small. Of late years, this branch of inquiry has been but little prosecuted, and the committee are not aware that any experiments, except a few in France, having in view a particular form of wheel, have been made, which tend to throw light upon the subject of their labours. Such was the progress 'made in this subject when the Institute undertook it, with a view to obtain such results as should afford to the millwright a sure and safe guide in his practice, and thus contribute essentially to the promotion of one of the most important of the mechanic arts. After frequent consultations of the committee, a plan of experiment was determined upon the preparations of apparatus for executing this occupied the autumn and part of the winter of 1829, and in the spring of 1830, the experiments were commenced. These occupied the committee until late in the following December, when the operations were finished for the season. The committee consider that so little remains to be done to complete the proposed series of experiments, that they would not be justified in delaying their report, and that the results obtained should at once be placed before those to * Sineaton's Experimental Inquiries, &c. (Taylor's Collection, 1794.) + Détermination Générale de l'effet des roues mûtes par le choc de l'eau, &c. 1769. Poncelte, Mémoire sur la roue Hydraulique verticale à aubes courbes. Ann. de Chim. et Phys. (1825.) |