398 WHY DOES A RAZOR CUT BETTER AFTER BEING DIPPED IN HOT WATER? 1st. I took a cord of 392 feet to the pound, to which I attached a weight of one pound, and applied it to a cylinder of dry ash-wood, turned in a lathe 1.75 inches diameter, and ascertained the force of traction necessary to raise this single pound weight, and found, when the cord was in contact with half the circumference of the cylinder, the force required was.... 2 lbs. at one and a half turns........ 13 ...... 31 66 3rd. I next took the line of 92 feet to the pound, loaded with one pound, upon a cylinder of cast iron, rough from the foundry, of 4.5 inches dia- WHY DOES A RAZOR CUT BETTER meter, and found the traction to be, At half a turn.. one and a half ...... 6 lbs. ..98 AFTER BEING DIPPED IN HOT WATER? [We insert the following letter, rather for the purpose of inviting discussion on the subject of which it treats, than as approving entirely of the explanations given by the writer. Some of his inferences, we think, will be found illogical, at least.-EDIT.] SIR, In answer to your Correspondent's (Novaculus) question, "Why does a razor cut better after it has been dipped in hot water?" In general terms, I would say, that as a sheet of sand-paper is cut by a pair of scissars with greater difficulty than a sheet of similar paper, but not sanded. The razor, before being dipped,has obstructions in itself to overcome, but which become removed by the water. This opinion is the necessary conclusion to be drawn from the fact, namely, that fire causes bodies to suffer loss of elementary matter universally, and communicates nothing whatever to them. In order to illustrate the case, it is necessary to divide it into two parts, viz. first, as respects fire being hot; secondly, as to whether fire takes from bodies, or communicates matter to them. First, As to fire being hot, the contrary is the fact-there can be no such thing in nature as a hot body, because there is no such thing as an element hot, sui generis; and because matter INQUIRY, ETC. being inert, is incapable of changing. its like from hot to cold, and from cold to bot. Inertia implies unchangeableness, as, where there is no power or ability, there can be no change of essence; and therefore heating and cooling unalterable matter, by matter which is inert, is highly irrational to imagine. In the next place, The means we possess, by which we become acquainted with heat, must convince that fire has nothing whatever in common with beat. Thus, when the hand is applied to an ignited coal, it is not the flesh which feels, as, without nerves, there would be no feeling excited, even were the flesh burnt. Neither do the nerves feel; for, when separated from the brain, and in all other respects remaining uninjured in the body, neither pin nor pincers applied to them can produce sensation. Sensation, then, is confined to the sensorium, which may be the brain-an organ that does not come in contact with the external body, which we suppose hot. Hence it is manifest that heat consists in sensation only, with which what is material can have no similitude, and that it is from imagining the external body to be in a state similar to the sensation that we conclude the body is hot. The term heat, in short, only applies to sensation, feeling, or when health is concerned. Secondly, Fire takes matter from bodies, and imparts none to them. This is the fact, notwithstanding it is opposed to universal opinion. Wood, paper, linen, damp clothes, fuel, and all combustible bodies, are deprived of matter by fire; so, when indecomposable bodies suffer physical change by fire, without loss of weight, it may be justly inferred that they also have been deprived of matter, although it may be only electric matter; for fire, it will be granted, cannot act otherwise than similarly on all bodies. What fire takes from water is visibly collected on the bottom of vessels before ebullition takes place, in the form of bubbles, that cannot be made to ascend in the water as long as the vessel is in contact with the fire. The denuded state of air, as respects vital matter, in which combustion is carried onthe oxidation, by fire, of metals in air -and the decomposition of water by ignited iron, wherein what the water is deprived of the iron, which is fire, acquires, amounts to a demonstration that fire takes some species of matter or other from whatever may be in con £99 tact with or in the neighbourhood of it. And as fire can act but uniformly, that is, cannot draw to it and propel from itself at the same time, it is conclusive there is nothing communicated by it to bodies; and that what is taken for radiation, is the effect of the abstraction which the air suffers by fire, or by bodies that have been rendered deficient of some species of matter by fire, by which these act on the thermometer as they have been acted on by fire. From which it would seem, that the deficient state of the water causes the sated (cold) razor to suffer loss of electric matter, and from the teeth of its saw-edge some of the like, that may be compared to grains of sand or to saw-dust, which, by sticking between the teeth of a saw, prevent it cutting with the same facility as when they are removed. I remain, Sir, INQUIRY. NO. 154.-ART OF TURNING. SIR,—I should be obliged to any of your readers to favour an amateur turner with the best apparatus for elliptical turning, and also with the mode of turning cubes with mathematical truth. I am informed it has been done so correctly as to produce a degree of cohesion sufficient to suspend no less than six pounds weight. I am, Sir, Your obedient servant, TURNSCREW. ANSWERS TO INQUIRIES. NO. 145.-WIND-LATHE. SIR. If your Correspondent, "E. B." is in the habit of visiting London, he may see a beautiful horizontal mill at Battersea. The sails consist of a large wheel, exactly like an undershot waterwheel, only much longer in the di 400 ANSWERS TO INQUIRIES-CORRESPONDENCE. rection of the axis; this is placed I am, Sir, NO. 134. F. O. M. VARNISHING STUCCO IMAGES. SIR,-Having an anxious desire of adding something to the stock of general knowledge, and having observed several answers to your Correspondent Aurum, elucidating various ways of preserving Stucco Images, I beg permission to offer one more method, and that a very simple one, but which none of your able Correspondents have noticed, probably from its simplicity. I purchased of an Italian, some months ago, the bust of Lord Byron; I kept it until perfectly dry. I trimmed it from all the superfluous marks left from the mould, and then immersed it in raw linseed oil for twelve hours (without any preparation whatever, save the trimming); I then took it out, and drained the loose oil from it: it wax. now has the appearance of yellow When it gets dirty, or flymarked, it will clean by washing it with a sponge and lukewarm soap and water. I am, Sir, Your humble servant, W. GILKES. 73, Wheeler-street, Spitalfields, 8th Sept. 1825. CORRESPONDENCE. A Correspondent (Tyne), who has lately discovered a Copper Ore Vein, which he supposes will yield 200 tons of ore annually, wishes some of our intelligent readers to inform him, what will be the expense of erecting a Smeltinghouse, to smelt that quantity of metal, and what would be the expense of smelt ing it? Coals are to be had in abundance in the vicinity. He would willingly pay any gentleman for proper plans and instructions. R. H. has favoured us with the following reply to Mr. Hall-(See Correspondence of last week): "SIR-My error,in page 309, has served other purposes besides being amusing: for one, it has given me a warning to be more particular for the future. I now see the error clearly: how it could escape my notice at the time, is more than I can account for. "The following, I believe, will be found correct:-Take the area of both ends, and a mean proportional between them; add these sums together, and take onethird for the mean area. For instance, from the dimensions given, page 308: 182+62 + √182 × 62÷÷3 = 156 = 13 feet. "I was aware of this method when I gave the other; but I imagined that the other came near the truth, and by more simple operations. I erred; I thank Mr. H. for pointing out my error; and I now give you a method not liable to this objection. "The error of G. A. S. is still conspicuous; and my proof of the erroneous principle on which it was founded will be found correct. R. H." Mr Hope will find the information he requests at p. 159, vol. iv. We thank Cesur Borgia for his different hints. That respecting the Praxis we shall very probably follow. His "New System of Fortification" will be acceptable. A Correspondent, alluding to the " Air Balloon of the 17th Century," says—“ [ cannot help remarking, that long before the discovery of Montgolfier, the principle and practice of the fire balloon were known in England. There are persons alive now at Ringwood, in Dorsetshire, who remember a doctor in that town that frequently let them off for his amusement, twenty years before ever Lunardi ascended in England. I have heard, too, of similar exhibitions before that in rarious other parts of the kingdom." A letter from a Correspondent to "Mechanicus" is left with our Publishers. G. U. A.'s letter did not reach us till after last week's publication. His former paper will appear in next week's Number. Communications received from--Alpha -Ben Mizen-Lucidus-C. Smith-H.S. -B. P. C.-Amicus-G. H. E.-B. J.R. R. Communications (post paid) to be addressed to t ACCOUNT OF THE TRIGONOMETER, A NEW INSTRUMENT, INVENTED BY MR. M. P. MOYLEY. SIR,—In January, 1824, I transmitted to the "Annals of Philosophy," some account of an improvement of the Clinometer, then generally in use for some of the operations of mining. It consisted of a quadrant affixed to it, on which was engraven the angle at which the instrument might be opened, and the length of base or underlay of a stratum or lode to a perpendicular fathom at any particular angle. I at that time stated to Messrs. Knight, of Foster-lane (who manufactured the instrument for me), as well as to many of my friends, that I intended to complete it, by the addition of another quadrant, on which should be graduated the measurement of the remaining sides of a triangle, where one side, and the angle from the perpendicular, were given. I have for some time accomplished this; and the prefixed sketch will, I hope, convey an accurate idea of it. Ι propose calling it a Trigonometer; for it completes the operation of measuring all kinds of triangles with the greatest precision and accuracy. It consists of two pieces of boxwood, AA, firmly united together after the manner of a rule; each part is 18 inches in length, and half an inch thick; one part is 2 inches in width, the other 2 inches. To these are occasionally attached two brass quadrants, II; they are made to slide in and out under the brass plates, BB, and may be fixed by the bolts, DD. CCC are three spirit levels, to prove the position of the instrument for various purposes; E is a small quadrant, divided into degrees only, and numbered both ways. F is a magnetic compass, with its scale divided into 360 degrees, also numbered both ways. This compass is hung by an axis, GG, so that it may always swing horizontally. HHHH are four sights; two are placed on the upper edge of the instrument, and two on the face of the lower half, in a direct line with the axis of the compass, and which are particularly useful in surveying, &c. The outer rim of the large quadrant has the angle in quarter degrees engraven on it, and numbered both ways; and when the instrument is open to any particular angle from the perpendicular (say 2640), the inner rim of the large quadrant gives rather more than 2 feet 11 inches for the length of base, or underlay of a stratum or lode, supposing the perpendicular to be one fathom. At the same angle, if the hypothenuse is one fathom, the base would be found, by the outer rim of the second quadrant, to be better than 2 feet 8 inches; and at the other edge the perpendicular will be found to be about 5 feet 4 inches. The reverse sides of these quadrants are also graduated, showing the hypothenuse when the perpendicular is given, and the hypothenuse and perpendicular when the base is given. The instrument is graduated, supposing that the radius is in all cases six feet, or one fathom; therefore, if the side or radius given should be two, three, or more fathoms, the amount obtained for one must, of course, be multiplied by that number. Caution should always be had that the angle is taken from the perpendicular; and where the angle is most conveniently observed from the horizon (as may be the case under peculiar circumstances), the complement of that angle (i. e. what it wants of 90°) must be used, which will be found to be the same as if the angle were had from the perpendicular. This, perhaps, may be more fully understood by the following diagram |