Ritchie on the subject, was recently, when he did me the honour to spend part of the day with me in Liverpool. In a word, the only individuals whom I can call to mind as having expressed a decided opinion in my presence, when in London, adverse to the undulating railway, were Mr. Saxton and a friend of his, whom I begin to think was Mr. Cheverton; and as to any acquaintance of mine then present being afraid of their "badgering," I rather think Mr. Cheverton has imbibed an erroneous impression. If it were necessary, I could publish, in this letter, a list of persons who are advocates of the undulating railway, amply sufficient to out-balance the strongest testimony which Mr. Cheverton and bis friends can advance against it, but the best testimony is practice, and upon that I throw the merits of the case. Lastly, Mr. Cheverton offers some important practical objections, which I confess to be more worthy of notice than any points which he has hitherto advanced. But, serious as they appear, they will not, on consideration, be found of any real weight. In the first place, we have to determine what is a safe velocity-that being determined, how can it be attained on a level railway with heavy loads? Unless gravity be employed at starting, as an auxiliary force, a much more powerful engine would be requisite to move a heavy load from a state of rest, than to continue it at a given maximum velocity; and if gravity be employed at starting, the engine and load must ascend again to a like summit, in order to maintain the starting advantage; and if so, what is this but an undulating railway? Does Mr. Cheverton imagine that a perfect cycloid, or a perfect arc, alone constitute my idea of an undulation? Far from it-he may descend a hill, run four miles on a level, and ascend to an equal elevation; and by doing this would realise a system of undula tion which might, probably, be adopted with advantage in some cases; for, with heavy loads, a velocity might be generated by the first descent which could not, with the same engine, be generated on a dead level; and this being maintained on the level, would enable the load to ascend to a like elevation. But supposing the undulations to be a series of regular segments of circles, wherein consists the difficulty of sustaining an average velocity of 20 or 30 miles per hour, without an increase of speed? Is it necessary to work the engine down every descent? One of the leading advantages which I anticipate, is the great saving of that steam expenditure which is now necessarily incurred in maintaining high velocities on a level. Again, it will require very powerful engines to attain high velocities, with heavy loads, on level railways: whereas, such powerful engines will not be so necessary on undulating railways, and for the reasons previously stated. I now, Sir, unless again attacked by Mr. Cheverton, close with pleasure this twelvemonths' warfare, anxiously awaiting the result of practical trials; and sincerely hoping, although a few waspish observations have occasionally intermingled with a subject to which they should have been altogether foreign, that some information and benefit may have heen derived from the discussion. I am, Sir, with great respect, Douglas, March 27, 1834. P. S.-S. Y. and I have, in one respect, misunderstood each other. He is certainly right in believing that the pressure upon an inclined plane (alluding to the force necessary to draw a body up) is as the base to the length: therefore, at an angle of 45°, my statement appeared erroneous; but, taking into consideration the resolution of the forces -that at an angle of 45° the length of the base is equal to the perpendicular elevation-and that taking the length of the plane as the entire force of gravity, it forms the diagonal to two equal sides of a square; the oblique forces are therefore equal—that is, at an angle of 45o, the force of gravity which urges a body down a plane, or retards its ascent, is exactly equal to the force of pressure on the plane. For instance, if L be the length, B the base, and E the elevation, at an angle of 45°, E is equal to B; and although the pressure on the plane is XL, yet the tendency to descend is E L B L XL; the one force, therefore, is equal to the other. I close my discussion with S. Y. with every feeling of respect, PRACTICAL HELPS TO A CHEAP COUrse of SELF-INSTRUCTION IN EXPERIMENTAL CHEMISTRY. Sir,―The extensive utility of chemical knowledge has caused it to be very generally, nay, almost universally, cultivated; but it is a branch of philosophy so entirely founded on experiment, that no person can understand it so as to verify its fundamental truths, unless he conducts experiments himself; it cannot, therefore, be uninteresting to devise such modes as may render the performance of these experiments easy, either by simplifying the apparatus, or by presenting such expedients and resources as shall readily be within the reach of every student. Some one has remarked that no good chemist can have clean hands; I will not admit as much as this, but it is universally acknowledged, that unless he operates himself, propriâ personá, and conducts his own experiments and analyses, he can be no real chemist. No one could be called a great traveller, who had only read books of voyages and travels by his fireside, though they comprised every one from Sir John Mandeville to Captain Ross. How, then, can we acknowledge a person to be a chemist whose science is founded on the authority of others, and who, when he finds himself in conditions for which he has no precedent in his books, is completely at fault? One experiment, well conducted and carefully observed by the student from first to last, will afford more substantial and permanent knowledge than the mere perusal of whole volumes; and, it may be added, that chemical operations are in general the most interesting that could be devised, were it merely for the sake of ainusement. Let us then proceed to examine some of the "means, and appliances to boot," that young chemists should possess. Dr. Henry truly remarks, that the notion that a laboratory, fitted up with furnaces and expensive and complicated apparatus, is absolutely necessary to perform chemical experiments, is exceedingly erroneous; in fact, diametrically opposite to the truth. For all ordinary chemical purposes, and even for the prosecution of new and important inquiries, very simple means are sufficient. Some of the most interesting facts may be exhibited by the aid of merely a few Florence flasks, a few com mon phials, and wine-glasses. Many most important discoveries in chemistry were made by persons who, either from choice or necessity, had recourse to utensils of the simplest character; for example, Dr. Paris, in his life of that admirable philosopher, Sir H. Davy, gives an amusing account of the extasies of the then young chemist, on his receiving an obsolete glyster apparatus from a French surgeon, who was shipwrecked on the coast of Cornwall, and his adapting this clumsy machine to the performance of his early and brilliant experi ments on light and heat. For the guidance of the chemical student, I have drawn up the subjoined list of articles which it is desirable he should be possessed of before commencing a course of experiments; several of them might certainly be dispensed with, but from the prices which are also added, it will be seen that the whole are within the reach of persons of even the most moderate means. They may be procured of great purity (and this is highly essential) of Mr. Dymond, 146, Holborn-bars; or of Mr. Davy, 390, Strand. I should recommend that the phials be arranged on narrow shelves, with a slip of leather nailed about an inch from the wall against which the shelf is fixed, and about three inches above the shelf, in which to support the phials. A good sound cork will securely close the mouths, except for volatile or corrosive liquids, for which bottles with ground stoppers are necessary. They must all be labelled according to the chemical nomenclature, as "Sulph. Soda," ""Nitrate Putass," &c. Another mode is to label compound bodies according to their atomic composition, by which means the proportional quantities of each constituent is constantly presented to view, and consequently easily horne in mind. For example, carbonate of potass is composed of one atom or equivalent of each constituent; I therefore write Potass + carbonic acid, i. e. potass plus, or added to, carbonic acid. The bi-carbonate would of course stand thus, Potass + 2 carbonic acid, or one atom of the alkali plus 2 of carbonic acid. To resolve them into their ultimate elements is, I think, unnecessarily complicated; otherwise the salt in question would stand, Oxide of potassium carbon with 2 oxygen (for carbonic acid) But in metallic salts, popularly so called, it is necessary to signify that it is invariably the oxide of the metal that combines with the acid, and not the metal directly; thus sulphate of iron is Peroxide of iron + sulphuric acid. The student will readily perceive that, as the atomic weight of iron is 28, of oxygen 8, and of sulphuric acid 40, the resulting compound will have the sum of them, or 76, for its combining proportion or equivalent. But to enlarge on this subject is not my present purpose, further than to suggest this mode of labelling chemical preparations to those who are already advanced in the science. The former and simpler mode will perhaps be the best for the adoption of beginners. The atomic proportions of the various salts, &c. may be found in many modern works on chemistry. LIST OF CHEMICAL PREPARATIONS, &c. muriatic 4 oz., same price. an excellent test for lime in solu- The three first acids must be kept in stopper-bottles, and mark always to take up with the stopper, before replacing it, the drop adhering to the neck of the bottle. Potass carbonate 1 lb. 8d.-This is the sub carbonate of the drysalters-it is purified by re-crystallisation. bi-carbonate 5 oz., per oz. 3d. caustic 1 oz., per oz. 6d.-Procured in small sticks, resembling slatepencils-it must be kept well excluded from the air, to prevent the absorption of carbonic acid. prussiate, or, more properly, ferro eyanate, 1 oz., per oz. 4d. chlorate 2 drachms, per oz. Is. bi-tartrate (the common cream of tartar) 1 oz. 2d. nitrate (saltpetre) 2 oz., per oz. Id. Soda carbonate 2 oz., per oz. 2d. bi-carbonate 2 oz., per oz. 3d. sulphate (Glauber salts) 2 oz., per oz. ld. Ammonia liquid 2 oz., per oz. 2d. carbonate 1 oz. 4d. muriate (sal ammoniac) 2 oz., per oz. 2d. Lime fluate (the fluor spar of the dealers in minerals) 1 lb. 6d. Magnesia carbonate 1 oz., per oz. 4d. sulphate (Epsom salts) 2 oz., per oz. la. Alumina and potass-sulphate (alum) 2 oz., per oz. ld. Iron sulphate (green vitriol) 2 oz., per oz. 2d. Copper sulphate (blue vitriol) 1 oz. 2d. solution oz., per oz. 6d.—A most Strontia carbonate, together with carbonate of barytes-may be purchased of dealers in minerals (native). Borax 1 oz. 3d. Tin 1 oz. 3d. foil 1 square foot 3d. Bismuth 1 oz. 6d. Mercury 3 oz. per oz. 3d. Zinc granulated 1 lb. 6d. Iron-filings 1 lb. 6d. The two latter to make hydrogen gas. Antimony sulphuret 2 oz., per oz. 1d. Tincture of litmus and nut-galls oz. each, per oz. 3d. Turmeric oz. 2d. Phosphorus oz., per oz. 5s. To be preserved under water, with the light excluded. Alcohol 4 oz., per oz. 2d. Roll-sulphur, flowers of sulphur, chalk, pipeclay, red-lead, of each a pennyworth. Some lumps of white marble, to make carbonic acid gas. Some newly burnt charcoal. Some thick polished iron and copper wire. Small articles of apparatus of great utility: -An iron ladle; a deep iron pot, to serve as a sand-bath; another for a water-bath; glass rods; clean straws and pieces of tobacco-pipes, to stir mixtures with; a few pasteboard and wooden boxes, with spare corks; a brass blow-pipe, which may be bought at the ironmongers for 9d.; a couple of Wedgwood-ware evaporating basins, utensils of great utility, as well for crystallisation as evaporation, as a strong heat may be applied to them without any danger of cracking, and they are unacted on by acids (those marked Nos. 5 and 7 are the most useful sizes, and cost, respectively, 9d. and 1s. 6d. at the china-shops); a Wedgwood-ware pestle and mortar, which may be bought at the same place, and they are of great strength (No. 1 is, a convenient size, and will cost 2s. 4d.); a ribbed-glass funnel, for filtration, &c., which will cost 6d. or 8d.; some glass tubes, of different sizes and bores, with which, by the aid of the blow-pipe to form small retorts, &c., a lb., at about 2s. 6d. per lb., at the glass-blowers. I have already protracted my letter to a great length, and must, therefore, reserve for my subsequent communications a notice of some other essential articles of apparatus, and of such substitutes as may easily be made at home, to answer the purpose of the more costly productions of the instrument-makers. I remain, Your obedient servant, MR. MACNEILL'S TABLES 7 FOR CALCULATING EARTH-WORK. Sir,-Although I have never seen Mr. Macneill's Treatise on the Cubical Contents of Earth- work, I will venture to make a few remarks on what has appeared in the Mechanics' Magazine regarding the accuracy of some of the rules in that work. Mr. T. O. Blackett, in Number 546, contends that Mr. Macneill has fallen into an error in the rule which he has given for finding the area of a vertical section of an embankment, declining from the horizontal line. Mr. Macneill's rule is stated to be this:-Let d and d be the perpendiculars, b the base, r the ratio of the slopes (this ought to have been "r the sum of the ratio of the slopes," then rd d'+ of a vertical section. d+db=area It is quite clear, from Mr. T. O. Blackett's first article on the subject (546), that he had no idea how the quantity r is determined from an actual measurement. He has, therefore, been under the singular necessity of applying his scale and compasses to Mr. Macneill's own diagram to determine the accuracy of the rule. Now, even granting that Mr. Macneill's diagram was perfectly constructed, Mr. Blackett has not taken the proper lines for determining the area (see fig. 2). In his answer to Mr. D. M'Callum (No. 555), he states that that gentleman has contrived to bring out an answer agreeing with that of Mr. Macneill's, by means of a false diagram. This is certainly true; and, moreover, Mr. M'Callum does not appear to know how the quantity r is to be determined, so as to prove the truth or fallacy of the rule; his diagram is truly inconsistent with the question. Mr. Blackett has attempted another solution (No. 555), which, I am sorry to say, is not a whit better than the first. He has calculated, by trigonometry, the line E F (see his own diagram), and the angles GEF, CFD, and the area of the quadrilateral E BC F, all rightly; but he has taken care to conceal the method he had recourse to in finding the area of the triangles ECD and A BE. The truth is, he has been obliged again to trust to the accuracy of his scale and compasses. But be that as it may, I maintain that Mr. Macneill's rule is perfectly correct. rd d'=112+72-184. Hence it appears that Mr. Macneill's rule is true. It might, no doubt, be asked-if it is necessary to determine each of the perpendiculars CG and DH by measurement, then, may not the area of the figure ABCD be calculated at once, without finding the value of r? And does not Mr. Macneill's rule only tend to mystify the subject? As I have never seen Mr. Macneill's book, I am not prepared to answer these questions in the negative. In all probability, however, Mr. Macneill must have had some good reasons for giving the rule under the form which he has done. Should the book ever happen to fall into my hands, I shall read it with attention, and communicate the result of my opinion of it to the readers of the Mechanics' Magazine. Yours, &c. KINCLAVEN. EFFECTS OF IMPROVEMENTS OF MACHINERY ON WAGES, AS EXEMPLIFIED IN THE COTTON MANUFACTURE. BY JOHN W. COWELL, ESQ. (From a Supplementary Report of the Factory Commission.) Improvements in machinery in all that regards cotton-working are not stationary for a single moment. The machinery which to-day is the most perfect becomes to-morrow second-rate, and very soon third-rate. The cotton, in its progress from the hands of the porter of the mill who unpacks the bale which comes from the merchant, to those of the overlooker of the mill who receives it from the spinner in the state of twist or yarn, (and which is the first shape in which it becomes once more a marketable commodity,) goes through a number of processes which it would be difficult to enumerate and impossible to describe. Each of them has its peculiar system of machinery, and an improvement in that appropriated to any one of these, affects directly the wages of labour in the process itself, and indirectly those in other correlate processes. effects onts of labour in the follow in machinery produce their ing ways: First, They render it possible to fabricate some articles which, but for them, could not be fabricated at all. Secondly, They enable an operative to turn out a greater quantity of work than before, time, labour, and quality of work remaining constant. Thirdly, They effect a substitution of labour comparatively unskilled for that which is more skilled. The first of these effects does not suggest considerations of such immediate importance to my present purpose as the two latter. They teem with consequences deeply affecting important social interests. The following is the principle upon which wages or earnings, in cotton-working by power, depend, and I beg particular attention to it: When the quantity of work executed by an operative in a given time is increased in consequence of an improvement in the machine on which he works, his remuneration per hour increases, his remuneration per pound of work done decreases. This principle obtains throughout, though many of the assistants are paid by fixed weekly wages; but as such are either in the direct employ of the superior operative, who is paid according to the foregoing rule or else under the entire control of the overlooker of a room of machinery, who is paid according to the quantity of work that his room turns out in a given time, the principle in reality prevails throughout. To illustrate the effect which an improvement in machinery produces on earnings, 1 will take an instance from the spinningdepartment. It will hold good mutatis mutandis for every other department. The spinner is the leading and most important operative in cotton working. He is the one for whom every preliminary process (called "the preparation," and consisting of carding, &c. &c. &c. &c.) is performed. So much weight of prepared cotton is delivered to him, and he has to return by a certain time in lieu of it a given weight of twist or yarn of a certain degree of fineness, and he is paid so much per pound for every pound that he so returns. If his work is defective in quality, the penalty falls on him; if less in quantity than the minimum fixed for a given time, he is dismissed, and an abler operative procured. The productive power of his spinning-machine is accurately measured, and the rate of pay for work done with it decreases with (though not as) the increase of its productive power. Since these machines are in a state of continual improvement, what effect is thereby produced upon the spinner's earnings? The mule, or spinning-machine, is a system of spindles. A spinner manages two |