( 100 ) NEW RULE FOR MEASURING ROUND TIMBER. SIR,-The following paper is the production of a person in this town, whose acquirements in mathematics, mechanics, and general knowledge, are entirely the result of his own abilities and application, without having derived advantages of any description from education-in fact, he was brought up as a bricklayer, and even follows that calling at the present moment. He was recommended by me to take in your admirable Work, with which, on all occasions, he expresses himself extremely pleased. Should you deem it worthy of appearing in your pages, he will feel much flattered; and, on future occasions, you may find him a valuable contributor to your work, and a striking exemplification of the power of natural talent. I am, Sir, your very obedient servant, St. Bartholomew's, near Sandwich, Kent. SIR, I take the liberty of requesting the favour of your inserting the following brief remarks, experiments, and subsequent calculations, relative to Round Timber Measure. Your Correspondent T. H.'s views on this subject agree with mine; but as T. H. has not illustrated the observations he has offered on this head altogether satisfactorily, in my opinion, I will, with due submission to him and the rest of your mathematical Correspondents, submit the following explicatory remarks: My principal intention is, to demonstrate an approximated method of measuring round timber; at least, such as may, in some degree, approach nearer to the truth than the rules hitherto generally made use of by calculators. But, before I proceed to give the experiments and calculations, I beg permission to lay down a general hypothesis, to be regarded as a standard in an investigation of a proposition which has for its object a new theory, which shall be every way subservient to the mechanical practitioner. Now, as irregular pieces of timber (trees) consist of various shapes, such as obtuse ellipses, distorted circles, and, in many instances, a sort of triangular or trapezi-angular formed sections (were the same sawn asunder in several places), to find the true mean area of the many sections or quantities contained within the circumscribing compass of the respective girts,. when taken by actual measurement, is what I apprehend to be the chief difficulty. The first particular to be observed consists in the method of girting the tree, or piece, whose con E. S. STRATTON READER. In tents are required; and the second is the mode or rule of calculation. regard to the former, the method of girting may be comprised in a general rule, to be observed with some restrictions, hereafter to be noticed. The method or manner of girthing I would recommend is, in the first place, to divide the length of the tree into several equidistant parts or portions, say five or six; then, with a small cord or line, as usually made use of, girt the tree where the points of division may happen to fall between the two ends, taking in at the same time the girt of the ends, or nearly so, as may be thought proper (vide remarks subjoined). This being done, the mode of arrangement and rule of calculation, in the latter particular, is as follows: Let G be the sum of all the girts, and n the number so taken : then will G be =m, the mean or common girt; and hence the rule of computation is n NEW RULE FOR MEASURING ROUND TIMBER. cured a tube sufficiently large to admit each piece separately, I filled the tube, having one end stopped, with water, and then reserved the quantity in a cylindrical vessel, to be properly guaged. The tube being now empty, I put in one of the models, marked No. 1, and then poured in the water I had reserved till the tube again was filled; the remaining water in the vessel being equal to the cubic quantity of the mo delized piece of wood. Then, with a guage or scale of equal parts, I guaged and calculated the respective quantity found in No. 1. I proceeded in this manner with the other two models, calculating the respective quantities in decimal proportion according to the divided scale of equal parts, setting down the result corresponding to each number or model. The next thing I had to attend to was to divide the models into equal portions, in order to girt each as per rule (obtained by trial); then, with a very fine thread, I began with No. 1, at one end, to girt the model, measuring the length of the girt by applying it to the same scale of equal parts as I made use of to guage the vessel. The length of each girt I set down, and collected their sum as per rule, which are as follows: Results and Calculations obtained by Experiments. To No. 2. Girts. 101 Quarter mean girt. To No. 1 = 9.475 1-5th of m. girt. 1=3 7.58 The reserved quantities, as calculated from experiments of immersion in the tube-dimensions of vessel omitted. Cubic quantities obtained. To No. 1, (accurate guaging)=7592.980164 To No. 1 To No. 2 59.8 Quantities calculated by the common Rule, hitherto generally practised. 9.4752 5} H 3731.6708 = To No. 3 × 66.22 5911 Decimals omitted. HARDENING STEEL-WHEEL-CARRIAGES. If one end of the tree be suddenly much larger than the rest, girt the mean or half the distance between where such suddenness of bulk commences. If the tree is regular throughout, from end to end, and the girt small, the rule, m 2 × 2x L, will not 5 greatly, if at all, exceed the truth. But as no trees are truly circular, the correcting factor, m x .025, should be used. Also, if a tree be of a triangular form, from end to end, the correcting factor should be mx .25; but, in all other cases, the preceding rule appears to me admissible, unless that any discovery in measuring leads the calculator to apprehend that the mean girt is too little, and, consequently, the mean area too little, which would be difficult to determine, as a variety of circumferences may occur in which there may be but little variation in the area of any respective section. Thus far I have attempted to establish a new rule for computing the cubic quantity contained in irregular pieces of round, unhewn timber The method of girting gives the equalizing area, and the rule of computation, in a few figures, the cubic quantity. 103 sharp-do sharp my knife!" is the order I now leave the subject to the correcting remarks which any of your mathematical Correspondents may think proper to make, and shall reserve other observations on this head for a future paper, trusting that what is here advanced may be found not undeserv- Fr ing a place in your esteemed work. الله B WHEEL-CARRIAGES. SIR,-It gives me some pleasure to see, in Number 90, page 90, of your valuable little work, the Mechanics' Magazine, an article copied from Nicholson's Operative Mechanic, just published on this head. By this I trust you will stimulate some of our manufacturers to set about improvement in good earnest before it is too late. For my own part, I have for some time past given up all hopes of ever having a good knife again, unless by chance. I wear out a great many pencils, and my wife (who has about thirty young ladies to teach writing) a great many pens, from the want of one. "Sharp, SIR, I shall be glad to know from some of the Correspondents of your valuable Magazine, qualified to give an opinion on the subject, whether any ease would be afforded to a horse by the adoption of a plan, of which I have endeavoured to convey an idea by means of the above draft. Description. A and C are the shafts of a carriage. EF, a bar connected with the carriage. Two springs are fastened to EF, and work against BD, 104 CANAL ECONOMY SHARPING RAZORS, ETC. G and N are two stops, fastened to EF, to prevent the springs being over strained, and against which BD would rest when the springs were strained to a certain point. The shafts A and C would pass through two holes made to receive them in EF, and would, together with BD, be moveable, so as to operate on the springs. I much fear I may not have rendered myself intelligible, as I am not at home at mechanical terms, and that my ignorance of mechanics may have induced me uselessly to trouble you; but, from the consideration I have been enabled to give this plan, it occurs to me, that by its adoption a horse would be much eased at starting, and on meeting with any obstruction in the road. I am, Sir, Your obedient servant, Bath. R. E. Halifax, Naturalist. He said, "the strops sold in the shops were covered with black lead:" so it rested-but mine set a finer edge, and I use it still. The discovery was simply this: A Bible, in rough calf, lay (except when used) on a pewter dish turned bottom up; the book being shoved thereon got a coating of metal; I was in the habit of strapping my razor on it, and found it shave better. than when done on any thing else. There was not then those facilities for such little (and, of course, useful) things being made public, as are now furnished by the Mechanics' Magazine and other works of a similar description. I am, Sir, Your obedient servant, A CLUMSY MECHANIC. Halifax, 29th April, 1825. CANAL ECONOMY. Mr. David Townsend, of Pennsylvania, has invented a method of saving water as the boats pass through the locks of canals, by which not a gill, it is said, will be lost. By the application of a machine, on all summit levels, no more surplus water will be required than will be lost by filtration and evaporation: there is no filling of locks by side or sluice gates, and the strength of a single mau,with a simple mechanical power, will do all the work, and pass a boat in half the time required on the present plan. SHARPING RAZORS. SIR, I congratulate mechanics on the appearance of your work : like the morning sun, your pages will disperse the mists and clouds which hang on the mechanic's horizon. Has he any doubt of his little discovery or invention being new, he can now make inquiry till he be satisfied, and then the way is open even to him, which was not so when I was young. Your second volume contains a method (from the Glasgow Magazine) of setting a fine edge on a razor: I have used the same for more than thirty years, and then mentioned it to James Bolton, of THE STEAM WASHING-BOX." INFORMATION WANTED. SIR,-Will you allow me to ask Mr. Haspy Smolet, through the medium of your pages, whether the description of the method of Washing by Steam, given by him in vol. IV. p. 21, is the result of actual trial successfully made, or otherwise? I ask this question, in the hope that such of your readers as may be disposed to make the trial, will defer doing so until they receive his answer; for, some years ago, in consequence of a similar account of washing by steam, in Rees's Cyclopædia, under the head Laundry, I made the attempt, very much in the way Mr. S. describes; and although I consider I gave it a full trial, I entirely failed. I tried the steam at 212 and higher temperature, and both soaked and soaped the linen previously, but could not produce the effect of cleaning it, though the linen was exposed to the steam ten or twelve hours, and consequently I concluded that some additional application of pressure or friction was necessary. I am, Sir, 7th May, 1825. |