357 512 REMARKS. At 40810, a stick only pierces the surface, solid below. Thermometer fell to 352o. Parts of the alloy liquid at stationary point. In one experiment thermometer rose from 3661o to 367°, alloy granular, semi-solid; fell to stationary point, alloy solid. By stirring, the upper point was obliterated. In one experiment the thermometer rose half a degree from 37610, then fell rapidly to stationary point. Thermometer rose half a degree above 3831o, in one experiment, and was stationary a short time at 38110, in another experiment; at both these times the metal was beginning to lose fluidity. Solid at lower stationary point. Thermometer fell very slowly from 387° to 3861, and alloy began to congeal at surface. The variable nature of the results, seems to point out rather the difficulty of detecting the upper point and the effect of accidental circumstances, than that it is affected materially by the impurity of the metals as found in commerce. This upper point rises with the proportion of the less fusible metal. The number of degrees between it and the corresponding point, for the solid state of the metal shows one difficulty to be obviated in the use of the fusible alloys. For example, the first in the table, just given, has 102° between the point at which it begins to lose fluidity, and that at which it is solid; the second has 111°, and the third 293°; these defects, it was hoped, would not have been 376 38231 found in alleys in definite proportions. They indicate that the variety of combinations in definite proportions is not considerable, if even it exceeds a single one; and that when the metals are mixed in definite proportions, the alloys are in fact combinations, or mixtures, of one or more chemical compounds with the metals themselves. If this be the case with alloys in which the proportions are in the ratio of the equivalents or in multiple ratios, it would seem to follow certainly, that in alloys made in proportions not definite, the same fact would appear. That this is so, and that its effects are of importance in practice, will appear subsequently. (To be continued.) sponding to the weight L moved up a plane rising 1, 2, 3, 4, &c. feet per mile. In all the cases it is supposed that the steam is so regulated as to produce a maximum effect. Suppose the full speed on a horizontal plane with a moving weight L is 30 miles per hour, and that with this speed the engine and train began to ascend a plane rising 16 feet per mile, and that it has been experimentally found on a level that the velocity due to a rise of 16 feet per Sir,-At the head of the "Notes and Notices" in your last Number (666) there is an extract from an article in Silliman's Journal on currents in water, where it is asserted, "that if a tub or other vessel is filled with water, and a hole made near the middle of the bottom of it to discharge it, the water will acquire a rotatory motion from west to south, or opposed to the apparent motion of the sun. The Guernsey Star re66 This cannot be the effect of marks, chance, but of natural laws constantly operating." In the same Number of your Magazine there is a communication from a correspondent, W. B. of Nottingham, wherein he states, that he has observed, "that the common scarlet runner, or French bean, always twists in one direction round the stick that supports it;" but he has not observed, or at least has omitted to state, that the direction which the scarlet runner takes is from west to south, or that opposed to the apparent motion of the sun. Again, the real motions of the planets is in the direction opposed to the apparent motion of the sun. Whether the same law governs all these motions, and very probably many more which have hitherto escaped our notice, is what I do not pretend to determine. Whether the same natural power that moves an atom moves a world, or whether, agreeable to the "Mackintoshian philosophy," electricity is the great moving principle that keeps all in life and motion, I am not philosopher enough to give an opinion; but I was 108 RAILWAY-CARRIAGE BREAK. MR. JOPLING'S RAILWAY HINTS-RAIL WAY-CARRIAGE BREAK. Sir, With due deference to Mr. Jopling, I beg to state, that the idea of applying bands or straps to locomotivecarriages, however new or novel, on railways, is not so as regards steamcarriages on common roads, a patent having been taken out by an eminent engineer some few years ago for the purpose; I believe, however, it was never brought into practice. The smooth and equable motion of the carriages on railways is certainly a powerful argument in favour of its adoption; as is also the introduction of the method used by Mr. Russell in his road steam-carriages; namely, dispensing with the crank-axle, and substituting either cog-wheels or wheel and pinion, thus gaining either power or speed; also taking the action of the engine off the propelling-wheels in an instant. A sort of basket, to precede a train of carriages to turn any impediment off the railway, was proposed in the Mech. Mag. No. 404, by Sir G. Cayley some years ago. Since the opening of the Greenwich Railway, I beg to state, that I have contemplated an addition to the locomotivecarriage, in the shape of a break,* applied either to the propelling-wheels, or to the whole four. The method is easy of adoption, and the mere act of shutting off the steam will bring the apparatus into play. As I cannot, however, just now spare time to make the illustrative drawings, or complete an experimental model, I must, for the present, withhold further communication on the subject, and am, Sir, your obedient servant, J. ELLIOTT, Machinist. 14, Stacey-street, Soho. We have been favoured with a description of the break now in use on this railway by the inventor, and shall give it in our next or succeeding Number. It is a very excellent one.-ED. M. M. THE LONG-WORK SYSTEM OF MINING. Sir, I am greatly obliged to you for the information you gave me in your excellent Magazine (vol. xxiv. p. 505), with regard to the mining of coal by the long-work system. You inform us that the Committee came to the conclusion that the present mode of working in the North was better than long-work, and yet Mr. Buddle does not deny that longwork is the best mode of ventilating a mine; and Mr. Mitcheson says, the current of air passing through long-work would keep it clear, and so prove an advantage. Now, sir, what did the Committee meet and hear evidence for was it not to get at the best mode of ventilating the coal-mines in the North of England, and, consequently, the saving of human life? Did not the evidence prove to them that long-work was the safest way to work the coal, and to subdue the gas, in the North of England collieries? Oh, but then we have tried this and the other method, and we like our own best; it is what we have been used to from our youth. And as to the loss of lives, we have been accustomed to that also, therefore we may as well go on as we are.' So, instead of adopting a method that would convey the atmospheric air round the face of the whole working, and to every living soul in the mine, the colliers are still to be employed in holes and corners where no atmospheric air can approach-destruction, ready upon every change of wind or density of atmosphere, to be forced out into the open roads and workings. From that moment the miscalled safety-lamp becomes a man-trap. Mr. Buddle in his evidence says, that he had tried the principle of long-work, generally called the Lancashire system (it is the Shropshire system of long-work I am contending for); but that induced a double mischief-too much small coal by the weight of the top behind pressing upon the face of the coal-If Mr. Bud die's long-work had been long enough and wide enough to have brought down the roof of the mine behind him, it would have lightened the pressure on the face of the coal, and instead of breaking the coal small, would have assisted in working it. "But the chief mischief," he says, "attending it, was the breaking of the strata up to the yard coal-seam, and bringing down double the quantity of gas." If it brought down six times the quantity of gas, a proper well-managed quantity of air continually kept in motion round long-work, would have swept it away. But the yard or Bensham coal should be worked before the next under it. I should very much like to know how Mr. Buddle's long-work was began; upon what plan it was opened; how wide and long it was when it grinded the coal to powder; whether the roof broke down at all behind him before he gave it up? I say nothing of the mode of working the thick coal in Staffordshire-that is not long-work; one thing only I would observe, some of the boys employed now on that magnificent vein of coal will be rummaging it over again for what is left behind by their present mode of working it. Mr. Buddle, speaking of the Bensham seam of coal, says, "I found it prodigiously fiery, so much so, that the coal itself afforded gas enough to light the pit. * * I drilled a hole into the coal, and stuck a tin pipe into it, and lighted it, and I had immediately a gaslight." Now, sir, that proves nothing at all extraordinary, because I have seen much greater intimations of fierceness than that, and the mine as sweet and clean of gas, at the time, as a house. I have seen oftentimes, when the colliers have been making a cutting across the seam about six or seven inches wide and three feet into the solid coal, a lighted candle has been put into the cutting, and the gas would ignite immediately and fill the cutting with flame, which would frequently keep burning till it was brushed out. No one in the mine cared a fig for such incidents as this, because they knew a current of air was passing along the face of the work, which would not suffer the flame to come out of the cutting. Mr. G. Mitcheson, on being asked if he thought the principle of long-work could be applied to the northern collieries, said, that "in many places in the North they had a post or stone roof that would stand forty or fifty yards upon an area; he did not think that long-work could at all be practised there, for it would never break down behind them, and there would be ten times more space for foul air than there is now." According to this witness the stone roof will stand forty or fifty yards upon an area, but I should not call that longwork; that is, stall and pillar work. I have seen walls of coal worked 400 or 500 yards in length. Does Mr. Mitcheson think the northern stone roofs would fall in that length behind him? I know they would, though I also know that a rock roof is not the best roof for long-work. The first sinking that takes place in longwork, after a sufficient quantity of coal is taken from under, to allow the strata to settle down, if the roof is very strong, shale or rock, often causes great confusion, and a novice in the trade would be soon inclined to abandon it. But an old longworker knows how to manage the weight to his own advantage, ever after, in working the mine. Why did not the Committee procure the opinions of some Shropshire long-workers? In that district the system of coal-getting is wholly longwork, whether the roof be stone, clunch clay, or even sand! I am, your obliged servant, THOMAS DEAKIN. Blaenavon, May 5, 1836. CIRCULATING DECIMALS. Sir,-Your correspondent, G. C. L., p. 43, is somewhat hasty in his assertion, that I have taken but a partial view of the question I proposed and answered, on circulating decimals. The rule I gave may be applied generally, though in some cases it requires a knowledge of several properties of circulates, some of which I referred to in my former communication. The ex ample attempted to be worked by G. C. L. may be considered as one case of the rule, and that proposed by me as another, though this is almost a distinction without a difference; for, in his example, the 1 denominator of the decimal is 0584 + that the decimal is a mixed circulate, the given part may be multiplied by that power of 2, the index of which is the number of terminate figures; this product, divided by the part of the least value, will give the numerator and the denominator found by the rule, being multiplied by the same power of 2, will give the required denominator. It is with regret that I am forced to observe, that your correspondent does not appear to have sufficiently considered the subject; in the second paragraph he "if we take any numerator for the says, the part therefore forming the circulate does recur with every multiplier. Having adopted an original method for exhibiting the circulates of any fraction, which affords a ready means for examining their several properties, I sub α join the circulates of as an example. | 33 | 34ths. 2 9 4 1 1 7 6 4 In these tables the upper lines are the numerators, or successive remainder, in finding the circulate by the common method; and the bottom lines the circulating series. The middle line is the terminate figures; these arise from all fractions whose denominators are divisible by 2, 2o, 5, 5", and they possess the same property as the series, viz, half being complements to 9 with the other half. By the arrangement, the commencing figure of the series is placed under its respective numerator. 34 |19|3| 13 | 11 | 25 | 29| 50 33 7 5 8 8 2 3 5 7 21313 |11| 8|12| 2 9 4 1 1 7 6 4 three series of 22 figures, and two of 1 figure. When m is divisible by 2 or 5, one added to the number of figures that circulate, completes the amount m−1. All the circulates formed from any denominator m, as above, are multiples of each other; consequently, if in the application of the first part of my rule the series are found to recur without embracing every figure produced by the |