180 LONDON MECHANICS' INSTITUTION. that they had expressed disapprobation at it. Now he wished to know if any law forbade the members memorializing? Some papers on the same subject, which had been placed on the walls of the theatre, had also been torn down. If this were not allowed, how were the members to communicate one with the other, (applause.) He thought that at any rate the committee should hear the members civilly, and give answer to their requests, them an (hear, hear.) Mr. M'William said, that the gentle man had been misinformed. The com. mittee did not express disapprobation; it was not their wish to reject the advice of their constituents; on the contrary, they invited it. They had refused to allow a paper to be placed up, for it was their opinion that no paper should be stuck about, of the contents of which they might be ignorant, (hear, hear,) and that if any member wished to bring any subject before the whole body, it was in his power to do so by calling a Special Meeting. (applause.) Mr. Lane followed on the same side, and observed, that no answer could be sent, as there was not a place of residence on the memorial. The Member observed, that if the committee had had any wish to send an answer, it would have been done; they knew well enough who to speak to about the sticking up of the papers. (hear.) Dr. Birkbeck said, that the memorial was so worded, that an answer was not even requested; it was merely dated the "London Mechanics' Institution ;" such being the case, the committee thought that the most eligible way of answering it, would be through the medium of the report. The apparatus room, &c. was not to be shut. Mr. Christie would attend and explain, and every one well knew how capable he was of so doing. (applause.) Mr. Ellis, one of the auditors, read his report, stating that he had examined the last half year's receipts and expenditure, and found all correct. The report having been read, a member complained, as he had formerly done, that only one auditor examined the accounts, whereas by law it should be done by more than one. He was a great stickler for the law, and would wish to see it altered or attended to. (applause.) Mr. Ellis explained and said, that it could not have been the intention of the framer that all should attend. (applause.) A Member inquired whether the £300 mentioned in the report, was the whole of the debt owing by the Institution? (hear, hear.) The Secretary said, that it was all the Institution was in debt-except the £3700, (hear, hear, and a laugh.) The same Member thought that the auditors ought to see that the expenses were not excessive. (no, no.) Dr. Birkbeck said, that every member might be an auditor, as by law the books of the Institution were open to them. (applause.) The Secretary read the Scrutineers' report. A proposition for increasing the subscription to 24s. per annum, was then put and carried by an unanimous show of hands, and loud clapping. A second proposition, that each new member shall on admission pay 2s. 6d. in addition, was then put and carried, but with not so numerous a show of hands. Two alterations, consequent on the above, were then put and carried. Dr. Birkbeck said, that the time had now arrived for suggestions and remarks on the report. Mr. Blake moved a vote of thanks to Professor Millington, for his "excellent course of lectures." The motion having been seconded, was carried by acclamation, Professor Millington in returning thanks observed, that he felt highly gratified at the manner in which his last course had been received; the subject was a very dry one, but the numbers who attended fully proved that they had in view the improvement of their minds. He hoped in the course which he shortly intended to deliver, to be able to present them with something of a more interesting nature, (applause.) A Member, in moving a vote of thanks to the auditors, for their excellent manner of auditing the accounts, observed, that as one of the sub-committee of accounts, he had an opportunity of witnessing the great pains they took to examine into every particular of the expenditure. Mr. Ellis returned thanks. Mr. Tijou moved, that the thanks of this Institution are due to Dr. Birkbeck, our excellent president, for the interest he evinces in promoting its welfare, (applause.) Professor Millington having seconded the motion and put it, it was carried unanimously with great applause. Dr. Birkbeck expressed his thanks for the very earnest and zealous manner PRACTICAL PERSPECTIVE. in which they had passed their vote of thanks. He regretted, that latterly his exertions in their behalf had not been so frequent as formerly, but he trusted that as the cause was removed, they would find that his heart was as warmly interested in their welfare as ever, (applause.) It was on account of his ill health, that his lectures on anatomy had been so long deferred. He looked forward to the time with pleasure, when he should appear before them. The subject was one, which as it applied to our structure and constitution, ought to be carefully and copiously explained. He hoped, that at the con clusion of the valuable lectures of Pro fessor Millington, to be able to commence them; fully impressed with a just consciousness of the importance of his subject, (great applause.) A vote of thanks was passed to the vice-presidents. Mr. M'William returned thanks in an excellent speech. A long discussion took place on Mr. Dufief's offer of a gratuitous course of instruction in French. A member observed it was a damper to many, when they found out that they could not be gin until they had paid 18s. for Mr. Dufief's books. Mr. Tijou said, it put him in mind of that class of doctors who give advice gratis, and charge only for medicine, (laughter and applause.) Mr. R. Taylor followed on the same side; Mr. D. was defended on the ground that his plan was excellent, and his books offered at a very low price. The sense of the meeting was, however, decidedly against Mr. Dufief and his liberal offer. Votes of thanks were then passed to the lecturers, the donors, the retiring committee; to the secretary, to the gratuitous and other teachers in the schools, to Mr. Bluett, the late apparatus keep er, &c. &c. and to Dr. Birkbeck, for his excellent conduct as chairman. The meeting then separated. 181 the height of the perpendicular 2, upon the ground that the former is one third further distant than the latter, from the point of sight at S. readers to the following theorem of To refute this, I must refer my Peter Nicholson: Theorem. The projection of a line parallel to the picture is also parallel to its original. Corol. 1.-The projection of several lines parallel to one another, and to the picture, are also parallel to one another. plane figure parallel to the picture Corol. 2.- The projection of any is similar to its original. HENCE, the original lines Ef, Ef, E E, ƒƒ, being respectively parallel to one another, and to the picture, they will also preserve their paral lelism in their representation. HENCE ALSO, the original rectangle Eff E, being parallel to the picture, its representation must be a similar rectangle, of a size reduced in proportion.* From these data it may also be adduced, that it is correct to place, if required, the perspective plane parallel to the original object, as in that case only, could original lines be parallel to one another and to the picture. I now ask for Alpha Beta's definition of parallel perspective, if he wishes to avoid the just retort of quibbling and evasion, or the charge of ignorance, as he unquestionably intended, his general rules for the representation of all rectangular figures, of which the two nearest sides are visible to the eye from the point of view, (page 47,) for we are by the above paragraph either led to the conclusion that he erroneously conceives the parallel projection of an object to be only a geometrical elevation; or that, finding his error too late, he endeavours to retreat by now informing us, "that the two general rules he had given, were In these demonstrations the prism dicularly upon the plan, and the picture or object is supposed to stand perpenparallel to it on the line JN; vide also appendix, page 120, vol. vii. Mech. Mag. 182 FRENCH WHEEL-BARROW. evidently enough intended only to generalise the rules for OBLIQUE PERSPECTIVE (page 147.) A small illustration may be here inserted of his system of placing the perspective plane in contact with the nearest point of the object. Imagine to yourself, reader, a design of St. Paul's the full size of the Cathedral; for such in theory (be tween which and practice he makes no distinction,) would be the effect of such a position of the picture. Necessity, indeed, is the only excuse for an occasional deviation in practice from the abstract principles of this point in the science; for the demonstration of the truth of these remarks, and of the correctness of producing to the picture the sides of the object, I beg to refer him to my appendix. I have no time at present to reply to his ungentlemanly insinuations, did I even consider them worthy of notice; but shall reserve a few additional observations upon his latter communication, until a future opportunity, or till my antagonist shall again call me to the field. FRENCH WHEEL-BARROW. H. M. S. London Institution. Sir, We were lately in our village all hands employed in making a dam across our common, for the purpose of collecting the water of a small stream into a lake in the centre, to which a poor body might at any time in the summer send his children to get a dish of fish; which would be a fine sight in the village to look at, and which would prevent certain greedy people in the parish from enclosing. Besides, our overseer, who is a topping man, and seems to know a good deal, says, that making the lake upon the common would improve the value of the farms hereabouts, as the lake would be such a fine and handsome object to look at, that numbers of gentlefolks with small fortunes, would be anxi ous to build houses around it, with two or three trees about them; and as they would have no land themselves they would be glad to get 'every thing they wanted from the farmers, such as grass and oats for heir horses, eggs, milk, chickens, * Evident-plain; apparent; notoriJOHNSON. ous. and butter, which last is here famous for being good. All this I believe to be very true, and quite possible; besides, it seems to me that there are never any cattle grazing upon our poor common, but flocks of geese, which would, I am sure, get fatter and flourish better in the water than upon dry ground. Well, as I have said before, we were all very busy about this dam. Our clerk, who takes in your Magazine, and who is, by the bye, a bit of a mechanic, told us he had seen in one of your late books a new plan for making springs somewhere about the axle-tree, by which a man with one of our common wheelbarrows would be able to carry as much as two men. Accordingly, I and the blacksmith, with the carpenter and the clerk, put our heads together, but we only made bad worse, and God knows what sort of invention we should have made of it, had not our clergyman, who came among us one day to see what we + Such necessity can only occur, when the plan has been drawn too small, which will sometimes happen. TABLE OF FACTORS. were about, told us he had seen in France a very odd-looking, but a very useful sort of wheel-barrow, and from his description we have made one. It seems to be a longhandled balancing sort of wheel-barrow, and will carry as much nearly as a cart with one horse with perfect 183 GISTERING THERMOMETERS. ease. All our people of the village ENQUIRY FOR THE METHOD OF REare mad at the sight of it, and all want to be having one like it. I have got orders for making some for them, and when they are provided, and we all set about the work upon our dam with one accord, we shall, please God, get through the work soon. I send you, Sir, a plan of the said wheel-barrow, (see prefixed engraving,) and if you should think it would be at all of any use in your Magazine, I hope you will put it in, that all my brother wheel-wrights in the country may get as many orders from their friends as I have. The wheel is two feet and a half high, the handle is eight feet, and it may be with or without springs. Such is the plan of our wheel-barrow, and hoping it will reach you safely, Believe me, Sir, to be Your most obedient servant, JOHN TURNER, Wheelwright. Sir, I should be greatly obliged Your obedient servant, INSTANTANEOUS LIGHT. Sir, I have tried several attempts to make matches for instantaneous light, but they do not answer my expectations. Your correspondent, N.B. page 173, vol. 5, does not say whether or not the matches are to be dipt in sulphur before using the paste. I have tried F. B.'s method, page *92, vol. 6, and find by using loaf sugar, the matches will not dry. When in London last Christmas, I saw a chemist fill a bottle-I shewed him my receipts, and requested some information, but could not obtain it. I am persuaded that the asbestos and sulphuric acid is correct for filling the bottle-and the ingredients stated for the matches may be also correct; but by my experiments, either the paste on the matches will not dry, or when dry will crumble off. I TABLE OF FACTORS. = Sir,-Perhaps it will be of service to some of your readers, to know that the table of factors in your 182d number, are the natural sines to the degrees there given; so that a person possessed of a table of natural sines, may see the factor to any angle; and by considering the hypothenuse 1 or radius, the perpendicular will be the sine, and the base cosine; and by calling the hypothenuse 10, the first figure (on the left hand,) of sines and cosines will be a whole number. The cotangent will shew the proportion between the base and perpendicular, i. e. the length of base to 1 of perpendicular-I find T. Whiting's table very portable and useful. I am Sir, - Your obedient Servant, |