288 THE GLASGOW MECHANICS' MAGAZINE. a number of years, Mr. Monteith caused to be removed the presses and utensils down to Barrowfield. I am, DEAR SIR, your's, sincerely, Extract from a letter of Mr. Miller's, Ballantrae : Post Office, Ballantrae, 12th April, 1824. DEAR SIR, After a careful perusal of the statement of your claims for the invention of the process of discharging Turkey Red Bandannas, in the Glasgow Mechanics' Magazine, for the 13th of March last, I do, without hesitation, pronounce your claims to rest on sure and solid grounds, and so can many others, yet alive, who were then at the Works. I went to Blantyre Works, as a teacher, in the month of July, 1797, and I left the works, 24th October, 1804. You were appointed sole manager of both Mills, and before Mr. James Monteith's death, which happened on the 16th July, 1801, you had completely succeeded in experiments on the discharging of Turkey Red, with brass plates of 16 holes. I well recollect the great secret of the spotting business, as it was then called. I recollect that Alexander Waterson cut the first screws for the large presses, and that Hugh Weir, Tinsmith, helped in casting the tin and lead plates. My old friend, Mr. George Strathearn, joiner, wrought constantly with you in the spotting house, (being agreed for that purpose), along with M'Callum, with whom I was not much acquainted. I am, SIR, your's, &c. JOHN MILLER. 1 The above attestations, I hope, are sufficient to convince every unprejudiced mind, that so early as the year 1801, Messrs. Monteith & Co., had completely succeeded in the process of discharging Turkey Red Bandannas, which, as is well known to the commercial world, has turned out a lucrative business. Now, allow me to ask, "What is it that Mr. Miller did accomplish?" He claims the merit of having invented a press for discharging, in the latter end of the year 1802, but he states that it was not seen until December, 1803. Presses were established at Blantyre Works two years before that. It may be very naturally supposed that he copied from them, but according to his own dates, it was impossible for them to have copied from him. His next invention, which is of the same date, are brass tubes or types. He says in No. XXIX., Vol. I., that 50 presses, with brass tubes, which had been made in Glasgow, were all working at once, a few years after his invention became known; all of these were in every respect made according to the first press constructed after his direction. Now, the question is, "What was the conseIt is quence of using his brass tubes?" well known that many individuals were ruined by them; others who were wealthy, abandoned them, as being destructive and unprofitable. Messrs. Monteith & Co., abandoned no part of their process, but these tubes alone. I now leave it to the public to judge, whether Mr. Miller, as an inventor, has any just claim of remuneration on Messrs. H. Monteith & Co. DAVID CAMPBELL. NOTICES TO CORRESPONDENTS. "Biggin" is informed that the Table he alludes to, is quite common, and the results are generally ascribed to the author quoted.-J. C. R., under consideration.-" Mirus" has fallen into the mire.— M. A. wishes L. M'L. to describe the plant he calls Neonan; and if he can't, advises him to take it to a Botanist, who would give it both the Latin and English name; would not M. A.'s plan of filtering be liable to this objection, that the sand would soon sink below the gravel?-G. M. P. must be more explicit with his improvement on the air-pump-We would thank G. S. for better solutions of the "Chronometer" and "Latitude" queries.-Rusticus's method of the weaver's beam was different, if we recollect right; we dare say B. T. won't dispute the originality of the rule for discount with him; we are more partial to the general demonstration of B. T. however, than the particular rationale of Rusticus; he is right in the Hill query.-A L...y under consideration.-E. E. has been received.J. S. has been superseded. Communications from intelligent Mechanics will be very acceptable, in whatever style they may be written, if they contain a full account of the invention or improvement, which is the subject of their notice. Published every Saturday, by W. R. M'PHUN, 155, Trongate, Glasgow, to whom Communications (post paid) must be addressed; may be had also of STEUART & PANTON, Cheapside, London; and EDWARD WEST & Co. Edinburgh. CURLL, PRINTER. DESCRIPTION OF AN INGENIOUS ALARUM APPARATUS. MR. EDITOR,-I have often intended sending you the under-mentioned article, but from want of time, I have not been able to send it sooner. I have no doubt but that many of your readers will be glad to see the construction of an Alarum, like the one I have sent, when it combines simplicity, utility, and cheapness, at the same time. One objection may be made to it, viz. that it requires a watch, and every person has not got that useful machine, but this may easily be obviated. The machine I have, and which I use every morning, goes by means of an old watch, fitted into a tin case. What is called a movement by the watch makers, (an article which they have always lying beside them, and which any person may buy for a few shillings,) may be employed, and by this means you may save your watch; for it is no advantage to have it lying open. If you should think this worthy your attention, you will oblige a constant reader, by inserting it, and I remain, dear Sir, yours, Aberdeen, Broad-Street, Oct. 23d, 1824. R. R. P. S.-I had nearly forgot to mention that this invention may be very well applied in securing windows or doors from the midnight thief, by attaching a piece of wire to the window, in such a manner, that when the window is touched, the wire falls, brings down the lever, and sets off the Alarum. I have also a contrivance for making it light a small lamp at the same time; but as it would be too complex it would be useless to send it. If it can be made simpler, I shall send you due notice for your useful Magazine. R. R. Explanation of the Figures. Fig. 1. A, a small wheel, with 13 wire pins on one side, having a groove cut round its edge, and into the edge another small pin fixed, for the purpose of setting the Alarum; a piece of cord is passed over the edge of the wheel, having a lead weight at each end, the one being 2 oz., and the other 3 oz. B, a small piece of wood fixed in the frame, and in which the hammer moves. C, a piece of wire, bent similar to the pallets of an escapement, having a piece of brass fixed at one end for the hammer. D, a piece of wire, moveable on a common screw nail, the end of the wire being bent up so as to catch the pin on the edge of the wheel. On the other end of the wire there is an eye, to which there is fixed a piece of cord, whose length must be determined, according to the height of the machine above the floor of the apartment. At the end of the cord, is fixed a piece of iron, E, (see fig. 3 and 4, page 297,) or wire flattened at the end, with a notch filed out of it, so that it may hang upon the pin G, which is fixed into the piece of wood H. On the top of H, there is a thin piece of brass F, which has a hole in its middle, and which must be made to fit easily, and have as little friction as possible, as the hour haud of the watch must cause this piece of brass to push the wire E. The weight of this wire (falling so as not to touch the ground) brings down the end of the lever C, when the large weight descends, and the bell rings till the cord is run out. K, an old movement, put into a tin case, which stands on the piece of wood J, into which the piece of wood H is fixed. The watch should be level with it, to remove the friction as much as possible. F, is I think the best form that can be given to the bell. The watch only requires one hand, namely, the hour hand. X, is the notch or clasp on the window, to which a piece of wire may be attached, as in fig. 1., to prevent the depredations of the mid night thief, by setting off the Alarum. The parts of the apparatus which are not marked in fig. 1., on account of their being so very small, will be seen quite distinctly in figures 3 and 4, page 297. Fig. 2 is a very neat form, which may be given to the apparatus, and which converts it into an elegant and amusing piece of furniture. ON THE EXPANSION OF GASES, With an Easy Rule, and a Table, for finding the Expansion of Air or any Gas, from 32° to 212° Fahrenheit. AN accurate knowledge of the expansion of gaseous bodies being of great importance in chemical researches, many experiments were made to ascertain it, but the results were long so various and different from each other, that none could be depended on. The reason of this difference was the want of attention on the part of experimenters, in not excluding with sufcient care the particles of water from the vessels employed to measure the expansion of gases. When, therefore, heat was applied to raise the temperature of any gas, the particles of water were converted into vapour, and mixing with the gas, produced a difference in the actual change of bulk which it had experienced. To this cause, indeed, can only be ascribed the variations in the determinations of Deluc, General Roy, and others, on this important point. The subject happened to engage the attention of two very able philosophers about the same time, namely, Mr. Dalton, of Manchester, and M. Gay Lussac, in France; and the coincidence in the results of their experiments is not only remarkable, but affords a convincing proof of their accuracy. Mr. Dalton published the account of his experiments about six months before M. Gay Lussac, and his ap paratus was much more simple than that of the French philosopher. It consisted merely of a glass tube, open at one end, and graduated into equal parts; after it was properly dried, the gas was introduced into it, and it was then filled with mercury at the open end to a given point; heat being then applied, the amount of dilatation was observed, by the quantity of mercury expelled. M. Gay Lussac's apparatus was rather more complicated, but capable of greater precision; and, as his experiments were made in greater quantities of air, their coincidence with the former induced perfect confidence in the accuracy of the results. Their experiments led to the important conclusion, that air, and all gaseous bodies undergo the same degree of expansion, by the application of the same degree of heat; so that the rate of expansion for one being determined, gives the rate of expansion for all. The expansion obtained by M. Gay Lussac, by heating air from 320 to 2120, was .375, or of its bulk at 32o, and that obtained by Mr. Dalton, was .376 for the same bulk. Now, this fact being established, that air expands about, or of its bulk, when heated, from 32° to 2120, or 1 2.666. 1 or part of its bulk at 180 480 82o. The experiments of Dalton for this would give about 1 479.8 + expansion, but the difference is of no great moment. From the experiments of Gay Lussac, it appears, that the steam of water and the vapour of ether experience the same expansion as air, when the same addition is made to their temperature; hence, it may be inferred, that all elastic fluids expands equally and uniformly by heat. To determine, therefore, the expansion of air, or any gas, at any temperature, or, in other words, to ascertain the increase of bulk which it undergoes, when heated from the commencement of the common thermic unit 32o, to any degree within its range, which terminates at 2120, we have only to add 1 480 part of its bulk, at 320 for every degree between that point and the temperature required. Thus, if the bulk of a quantity of any gas at 320, be 10 cubic inches, and its bulk at 60o be required, we have only to subtract 32o from 60°, and the remainder 28 is the number 1 of degrees intervening; then X 480 crease of volume, which, added to 10 cubic inches, makes 10.2008 cubic inches, the bulk of the gas at 50°, when raised to the temperature of 600. If the bulk of a quantity of gas at a higher temperature be given, and its bulk at a lower temperature be required, we must then subtract 320 from each temperature, and add the remainders to the denominator of the fraction; then making the least sum the numerator, and the greatest the denominator of a new fraction, we proceed with the operation as before. Thus, to find the contraction of 10 cubic inches of gas at 800 when cooled to the temperature of 60°, we have 60o-320 =28°; and 800 300 = 40°; also, 800 60° 20°; hence, 480 + 28 508 480 + 48 528' of a unit for 20°; wherefore, = the expansion X 10 cubic inches = 508 528 5080 528 9.4318 cubic inches, the volume of the gas at 80o, when cooled down to the temperature of 60o. |