and universal transmutations of matter. I will venture to hope that the foregoing little remarks of mine may, by your indulgent readers, be taken for humble and familiar illus trations of some of the facts Mr. Allan adverts to. What treasures of useful knowledge would rapidly be brought forth to improve the moral and physical condition of mankind, were not those on whose education most time and money are expended, chained down for years, almost exclusively to the parrot-like acquirement of mere words and sounds, in which any "learned doctor" would be beaten hollow by a resuscitated Roman or Greek infant of seven years old! The polish and the ornaments are mistaken for the foundation of the structure itself. Your collegian will for years bewilder his poor head with abstract qualities, without any substance to support them, as whiteness without a white body-motion without matter, which is its essence! Happily for mankind, although the present generation still behold the bewigged and belawned buffoons of universities and colleges enacting discussions on the nature of the light of mount Tabor, on the accent of a Greek word, and stupifying themselves and hearers with insane metaphysical jargon, thanks to Mechanics Magazines, Mechanics' institutions and lectures, the more worthy and useful members of the community are beginning to study things of real existence and utility, and are learning the best possible means of benefiting themselves by contributing to the felicity of their fellow-creatures. Thus will they soon discover the fundamental principles upon which the improvement and happiness of society depend. For instead of reasoning on phantoms, reality is beginning to be the basis of their inquiry; and the mind, resting on that solid foundation, may accumulate an extent of science, of which at present we can form no idea. Sentiments of the noblest delight must accompany every addition to such knowledge-knowledge of realities and facts, which can only be obtained by the free unrestrained operations of thought, with no other Your obedient, humble Servant, 25th Sept. 1826. (To be continued.) 368 4)5(1 4 1)4( 4 176 VULGAR FRACTIONS. thus is the answer required. 547 Consequently it is in its lowest terms. N. B. Mr. Jones's answer to the 1st question is not correct, on account of his having taken 567 for the denominator, instead of 576; wherefore, instead of having the numerator (192) go exactly three times at the first division, he has made a good luck, has got the same common long sum of it. He, however, by again by it, instead of 576; wheremeasure, but then he has divided 567 fore his answer is instead of 4. His answer to the third question is correct, but not very neat; in the latter end of the division, he has 15)135(8 120 15)15(1 15 instead of { 15)135(9 135 (See Mr. Stert's ans.) His answer to the sixth question is incorrect from the same reason as that of Mr. Pearson. H. O. (Formerly, 1 and 2 make 3.) NOTICES TO CORRESPONDENTS. Opinions on the Case submitted in our last, have been received from W. C.-N. H.-A.-Mr. Maynard (whose former communication never reached us)-Zelid-and Q. Q. In our next, we shall give the commencement of, what we believe is much wanted, a Treatise on Perspective, as applicable to the correct delineation of machinery. Samaht Keah guesses rightly: his Enquiry in our next. Communications received from Mr. Loudon-E. W.-B. West-B.-J. M. N.-H. H.-Mr. Burns-P. K.-Delos -J. Bromarch-and Mr. Allen. Communications (post paid) to be addressed to the Editor, at the Publishers', KNIGHT and LACEY, 55, Paternoster Row, London. Printed by D. Sidney, Northumberland Str Strand Mechanics' Mayazine, MUSEUM, REGISTER, JOURNAL, AND GAZETTE. No. 161.] SATURDAY, OCTOBER 14, 1826. [Price 3d "A man's genius is always, in the beginning of life, as much unknown to himself as to others; and it is only after frequent trials, attended with success, that he dares think himself equal to those undertakings in which those who have succeeded have fixed the admiration of mankind." 370 COMPARATIVE PROPORTIONS OF STEAM ENGINES. CHIMNEY SWEEPING MACHINES. Sir, The inclosed attempt at machines to supersede the necessity of employing boys to sweep chimneys are at your service, if you think they are likely to succeed; at all events, they may, amongst your numerous readers, suggest some plan of more practical utility. T. B. Sun Tavern Fields, St. George's, East. Description. Fig. 1. The four lines, a, a, a, a, represent the four corners of the chimney; B, is a perpendicular rod; C, a fan or wing, of which there are two on each side of a chimney, one sliding over the other in the same manner as a fan opens. The inner fan has a nut, D, which passes through the groove, E, in the outside fan, and which connects them together, and allows them to expand in proportion to the width of the chimney, as in figure 2nd, where the fans are expanded; these fans are fastened to the upright rod by a hinge at F; G G, are small rods extending from the upright rod to the corners of the chimney; they are hinged on the weight, H, which slides freely up and down the rod, B, and these small rods, G, G, are so fastened to the corners of the fans they pass through, that they allow the fans to expand, but to slide in and out. Now, if the chimney should increase in width, the weight, H, immediately descends, the rods GG, extend, and the fans extend in proportion, by which means every inequality of the chimney is provided for. Again, the ends of the rods being always parallel with the corners of the fans above, preserve the machine always perpendicular to the direction of the chimney. I, I, I, I, are small wheels attached to the ends of the rods and the corners of the fans, to facilitate the passage up and down; K, is a brush fixed to the top of the upright rod, to clear the chimney-pot Fig. 3, is a square machine, consisting of two flat boards or frames on each square, which extend themselves by incans of a groove and rim, in the same manner as that described before. The corners are extended by the rods, B, B, B, B, which are hinged on the sliding weight, C; the rods, D, D, D, D, below, are the same length as those above, and are fastened to the upright rod by hinges, E, E; this, of course, acts on the same principle as the former one, and has wheels at each corner, as shewn in the figure. The second, figure 3, exhibits a view of the interior of fig. 3.; Fig. 4, is a machine similar to the frames of two umbrellas, one inverted over the other on the same rod; the lower frame is fixed to the rod as at E, the upper one is fixed to a sliding tube as at A, which is connected by two wires to the lower weight and tube, B; this tube has the square, C, round it, having pins projecting from the sides of the square, to keep the rods equidistant, and likewise to keep them in a square position to the chimney. The rods are connected together at the parts they cross, as at D, by rings or pins forming a loose joint. If a line were passed through a pulley above the sliding tube, A, the operator might, by pulling the line, relieve the machine in descending, and this line applies to all the machines. COMPARATIVE PROPORTIONS OF STEAM ENGINES. Sir,-Your correspondent who has stated, at p. 293, the diameters of the cylinders, and lengths of stroke of three steam engines of 70 horse power, lately made for steam vessels by Messrs. Boulton and Watt, Mr. Maudsley, and Mr. Fawcet, has omitted to mention the number of strokes which the different engines are intended to make per minute; this is an essential particular for any computation on the power which an engine can exert; for other circumstances being similar, the powers of steam-engines will be proportionate to the quantity of steam expended by them in a given time; so that a smaller cylinder, whose piston moves quicker than that of a larger one, may exert a greater power. The proportions originally established by Mr. Watt, for the eylin |