128 ENGLISH MECHANIC AND WORLD OF SCIENCE.-No. 292. The Enfield bullet being 100 grains heavier than the Chassepot, and being fired with 15 grains less powder, it has a much lower initial velocity; being of large diameter, the atmospheric resistance to it is great, so that even its comparatively small initial velocity is rapidly reduced. Even the first 300 yards is traversed by the heavier Whitworth bullet (of 530 grains) in less time, and from that point onward its superiority in accuracy and penetrative power increases with the range. the Enfield at 1,000 yards is too wild to admit of The shooting of comparison with the other. The Prussian bullet is of the same weight as the Enfield, and fired with the same charge. Its diameter is somewhat less, and if other things were equal, its range, &c., should be for that reason superior to the Enfield's; but as a matter of fact they are worse, owing to its large bore and the large paper envelope of the bullet. JOSEPH WHITWORTH & Co. 44, Chorlton-street, Manchester. be in conjunction with x Leonis at 2h. 40m. in the [OCT. 28, 1870. satellite at 11h. 3m. The egress of satellite 3 from transit will occur at 7h. 50m. on the night of the 23rd. The 1st will be eclipsed at 4h. 33m. 12s. the next morning. on the the During the early morning of the 25th the shadows will pass off at 4h. 6m., the satellite at 4h. 35m. 1h. 52m., that of satellite 1 itself at 2h. 2010. The ingress of the shadow of satellite 1 will take place at This satellite will be eclipsed on the night of the same day at 11h. 1m. 42s. occur at 8h. 20m., and that of the satellite at 8h. 46m. at 1h. 41m. the next morning. 26th the ingress of the shadow of the 1st satellite will It will reappear from occultation On the night of the 11h. 1m. The shadow will pass off at 10h. 35m.; the moon at be an eclipse of the 3rd satellite. The 1st satellite will reappear from occultation at 8h. 7m. At 5h. 17m. 13s. a.m., on the 27th there will night of the 27th, and an eclipse of satellite 2 will ceeding early take place at 3h. 51m. 7s. in the sucnight of the 29th the ingress of the shadow of the morning of the 28th. On 2nd satellite will begin at 9h. 58m., and the transit of the satellite at 10h. 41m. The egress of the shadow will a.m. on the 30th. On the night of the 30th at 7h. 17m. occur at 12h. 35m., and that of the satellite at 1h. 18m. the ingress of the shadow of the 3rd satellite will com. 11h. 8m. The shadow will pass off at 9h. 51m., the planet at mence, and that of the moon casting it at 8h. 39m18h. 27m. 26s. (astronomical time) on the 30th of Finally, the 1st satellite will be eclipsed at November, or, according to our civil reckoning, at the sun now to be conveniently observed. He is on 6h. 27m. 26s. in the morning of December 1st. Saturn is still an evening star, but sets too soon after and on the 30th at 1h. 16m. the meridian on the 1st at 2h. 57m. in the afternoon, the confines of Ophiuchus into those of Sagittarius. He is travelling from from the constellation Gemini into that of Cancer. He favourable position for observation. Uranus is an evening star, and is coming into a rises soon after 9 at night, in the beginning of the He is passing Cancri, a little to the west of which he may be found. The only star of any size in his neighbourhood is 2 month, and about a quarter past 7 at the end of it. crosses about 8h. 30m. on the night of the 30th. He He is on the meridian on the 1st, at 10h. 32m., and Neptune is also an evening star, and visible all night. remains in the constellation Pisces. ASTRONOMICAL NOTES FOR NOVEMBER. BY A FELLOW OF THE ROYAL ASTRONOMICAL SOCIETY. THE right ascension of the sun at Greenwich mean noon on the 1st of November is 14h. 25m. 59.888., and his declination sonth 14° 28′ 17.3". He is consequently self, his satellites will present a series of interesting In addition to the physical features of Jupiter himin the constellation Libra, and situated to the W. by phenomena. N. of the star a in it (vide map, Vol. X., p. 545). Hegress of the shadow of satellite 1 will take place. It At 1h. 41m. a.m. on the 2nd the inrises on the 1st day of the month in London, at 6h. will be followed at 2h. 38m. by the satellite which 56m. a.m., and sets at 4h. 32m. p.m.; and on the last casts it. At 3h. 20m. the shadow of the 3rd satellite will day at 7h. 44m. a.m., and 3h. 54m. p.m. respectively; satellite will pass off. At 4h. 53m. satellite 1 will itself come on to Jupiter's limb, at 3h. 55m. that of the 1st the night at this latter date being thus obviously nearly leave Jupiter's face; and at 5h. 50m. the shadow of satel16 hours long. The equation of time to be subtracted lite 8 will also pass away. from that indicated by a meridian instrument or sundial amounts on the 1st of November to 16m. 17.178., 2nd, and it will reappear from occultation by the planet lite will take place at 10h. 51m. 21s. on the night of the An eclipse of the 1st satelat 2 o'clock the next morning. On the night of the 3rd to Jupiter's limb, as will the satellite itself afterwards at 8h. 9m. the shadow of the 1st satellite will come on at 9h. 5m. The egress of the shadow will occur at 10h. 24m.; that of the moon at 11h. 19m. Satellite 1 will reThe ingress of the shadow of the 2nd moon will take be sedulously watched for by every earnest student. appear from occultation at 8h. 27m. on November 4. between the 12th and 15th of November will, of course, The marvellous star shower which annually recurs place 55m. after midnight. Later, at 2h. 44m. a.m. on It may be expected on the early morning of the 14th, the 5th, the satellite will follow its shadow. shadow will pass off at 3h. 31m., and the satellite at present, on the wane, and that no such an astounding The although it seems to be tolerably certain that it is, at 5h. 21m. a.m. be subsequently occulted by Jupiter at 8h. 50m. From be kept after midnight every night between the dates The 3rd satellite will reappear from spectacle as amazed and almost appalled us in 1866 eclipse at 7h. 37m. 8s. on the night of the 5th, only to this occultation it will reappear at 11h. 18m. can reasonably be looked for this year. 6th satellite 2 will disappear in eclipse at 8h. 3m. 19s. because the radiant point, from which the major part Watch should after 12. The shadow of the 1st satellite will come until then. Many persons, in ignorance of this, during On the which we have specified. We say on to Jupiter's disc at 3h.34m a.m., on the 9th, and satel- the last three or four years have terminated their vigil reappear from a subsequent occultation 23m. of this astonishing rain of fire emanates, does not rise "after midnight' place at 5h. 49m. It will be daylight before the moon lite 1 at 4h. 24in. The egress of the shadow will take at 12 o'clock, under the impression that as, up to that passes off. At 45m. 10s. after midnight on the 9th. therefore they had mistaken the night; the simple hour, no conspicuous shooting stars have been visible, satellite 1 will disappear in eclipse. from occultation at 3h. 46m. the next morning. It will reappear fact being, as we have said, that the part of the the night of the 10th at 10h. 3m. and it will itself The association of the November stream of meteors ingress of the shadow of this same moon will occur on above the horizon when the watch was relinquished. The heavens whence the stream appears to issue, was not commence to transit Jupiter at 10h. 51m. 11th. On the 11th satellite 1 egress of its shadow will take place at 12h. these columns. One thing we would endeavour to urge The with Tempel's comet has already been referred to in 18m., and its eclipse at 7h. 13m. 36-7s., and reappear from occul- naked-eye acquaintance with the heavens. The reason Own at 1h. 15m. a.m. on the tation at 10h. 12m. During the early morning of the for this is not difficult to apprehend; it is that the path will disappear in coming display, and that is to obtain, at once, a good upon all those who may propose to observe the forth12th the shadow of satellite 2 will enter on the planet's of any very conspicuous individual meteor may be resatellite will leave Jupiter's disc at 7h. 32m. p.m. on limb at 3h. 30m., followed by the moon casting it at corded with all attainable accuracy. Two such observa5h. 2m. The shadow will pass off at 6h. 6m. The 1st tions made at stations widely separated may be of the the 12th. The 3rd will disappear the same night in and hence the distance from the earth of the body to eclipse at 9h. 17m. 468., will reappear from this eclipse which they refer. utmost possible service in determining the parallax, at 11h. 37m. 35s.; only however to be occulted by this occultation at 2h. 43m. a.m. on the 13th. Jupiter 16m. after midnight. It will reappear from the night of the 13th satellite 2 will suffer eclipse at 10h. 39m. 19s., and will reappear from occultation On at 2h. 42m. the next morning. The shadow of the 2nd satellite will pass off Jupiter's limb at 7h. 24m. increases on the 3rd to 16m. 18:31s.; and then, beginning to diminish, is on the 30th only 11m. 8:47s. The sidereal time at mean noon (or right ascension of the meridian, at the instant that a properly-regulated clock indicates 0 hours) is on the 1st, 14h. 42m. 17.07s., and on the last day of the month, 16h. 36m. 87-19s. The mean time at sidereal noon (or mean time of transit of the first point of Aries) is 9h. 16m. 11:57s., on November 1st, and 7h. 22m. 10.17s. on November 30th. The moon is full at 7h. 32m. a.m. on the 8th ; enters her last quarter at 8h. 59m. a.m. on the 16th; is new at 1h. 21m. after midnight, on the 22nd, and enters her first quarter at 10h. 33m. p.m. on the 29th. She is 7-9 days old at Greenwich mean noon on the 1st, 8-9 days at the same hour on the 2nd, and so on. in the afternoon of the 16th, libration will bring an At 1 o'clock additional portion of her S.E. limb into view; and on the 28th, at 3 p.m., more of her S.W. surface will become visible from the same cause. on the 11th the moon will be in conjunction with Jupiter; At 3h. 21m. p.m. and at 5h. 12m. a.m. on the 14th with Uranus, whom she may occult as viewed from stations far to the north of Greenwich; but whom, at that place, she will pass just clear of. She will be in conjunction with Mars on the 17th, at 1k. 6m. p.m.; with Venus on the 22nd, at 5h. 43m. ; with Mercury 8m. after midnight on the 22nd; and finally with Saturn at 8h. 25m. p.m. on the 24th. There will be three occultations of fixed stars by the moon this month, and-as has just been intimated-one very near approach of our satellite to the planet Uranus. She will also be in close proximity to 81 Tauri at 10h. 3m. p.m. on the 9th. Later on the same night 63 Tauri will disappear at her bright limb, at 11h. 26m., reappear at the dark limb 11m. after midnight. At 8h. 49m. in the evening of November 14th, 39 Cancri will disappear at the moon's bright limb before she has risen. After she has been up for half an hour, at 9h. 34m., the star will reappear at her dark limb. 40 Cancri will be occulted under precisely similar circumstances, its disappearance and reappearance occurring almost simultaneously with those of 39. It will be hidden at 8h. 50m., and emerge at 9h. 38m. Mercury is a morning star up to the 22nd, when he is in superior conjunction with the sun. will of course travel to the east of the sun, and become After this he an evening star. He souths on the 1st at 10h. 57m. It is evident that he is about as badly situated for observation during this month as he possibly can be. Venus is also a morning star, and (approaching as she is, like Mercury, to her inferior conjunction) in a most unfavourable position for the observer. She souths on the 1st at 11h. 10m. a.m., and on the 30th at 11h. 41m. a.m. She is in conjunction with Mercury at 8h. 36m. in the evening of the 11th. a.m. Mars continues to be a morning star. He souths on the 1st at 7h. 36m. a.m., and on the 30th at 6h. 39m. a.m., setting at about a quarter to 3 in the afternoon of the 1st, and about 1h. 19m. p.m. on the 30th. Although his apparent diameter is now very slightly increasing, he still presents merely the effect of a large red star, and will by no means repay telescopic observation. It is perhaps scarcely worth while to mention that he will and SCIENTIFIC SOCIETIES. THE OBSERVING ASTRONOMICAL SOCIETY. Report of Observations made during the period from p.m. on the 15th. the shadow of the 1st moon will enter on to the The satellite itself will do the same at 8h. 47m. planet's limb. At 5h. 29m. the next morning The moon itself will follow it at satellite 1 will disappear in eclipse at 2h. 39m. 7s., observed in August was repeated, though in a rather less 6h. 9m. During the early morning of the 17th SOL OLAR PHENOMENA-Mr. Thomas G. E. Elger writes-"The magnificent display of solar spots and reappear from occultation at 5h. 31m. satellite will enter on to Jupiter's disc at 11h. 57m., mainly confined to the South hemisphere; on the the night of the same day the shadow of the 1st and 12th, the spots were small, few in number, and On striking manner, during September. Between the 7th after midnight. The shadow will pass off at 2h. 12m. The immense group observed last month, and which and will be followed by the satellite projecting it 36m. 11th, only three moderately-sized groups were visible. a.m. on the 18th, and the satellite 38m. later. 9h. 7m. 35s. at night on the 18th the 1st satellite will be at the E. limb about the 17th, but owing to unfavoureclipsed. It will reappear from its subsequent occul- able weather and absence from home I did not notice At was near the centre of the disc on August 30, was due shadow of satellite 2 will pass on to the face of the ou including the outlying penumbra which followed tation behind the planet's body at 11h. 57m. The it till the 24th, when it measured 2′ 45′′ by 1′ 50′′ withplanet at 5m. past 6 the next morning. On the 19th it; its length on the 25th was 3' 0". 7h. 2m. The egress of its shadow will occur at 8h. 41m., contained four large umbræ and many smaller ones; the transit of the 1st satellite will commence at of this group presented some remarkable features. and that of the satellite itself at 9h. 16m. During the The penumbra It succeeding early morning the 3rd satellite will disap- numbral matter, on the preceding side it was fringed with wispy peoccultation at 6h. 5m. pear in eclipse at 13h. 17m. 9s. and reappear from minute dots of every shade from black to light brown. eclipsed at 1h. 15m. 14s. a.m. on the 21st, and reappear 25th the entire group was evidently undergoing rapid which was thickly studded with from occultation at 6h. 59m. a.m. afterwards. The 2nd satellite will be! When examined with a power of 180 at 3. on the shadow of this satellite will, on the night of the 22nd, the dark spurs and serrated edges of the umbræ enter on to the limb of the planet at 7h. 23m., and be clearly indicating the cyclonic nature of the forces inThe and violent changes, the striations of the penumbra and followed by the moon casting it at Sh. 26m. The egress volved. The above group was preceded by a very long of the shadow will take place at 9h. 59m.; that of the and narrow V-shaped spot, which occupied nearly the (EDINBURGH BRANCH). THE ordinary monthly meeting of this society was same position as a large spot observed in August. ENGLISH MECHANIC SOCIETY OF ARTS Time. Length. Width. Length. Width. 21.-21h. 25m. abt. 72,000 23.-21h. 25m. 63,000 25.-21h. 80m. abt. 70,000 Mr. Kemp thereafter read a paper on "A Method of Heating Railway Carriages by Steam." The method proposed by him was to carry the "exhaust" steam along the train in pipes. The engineers present pointed out that the exhaust cannot be used for any such purpose, it being all required for the "draught" of the furnace. The matter is to be again brought up. It was announced that at the November meeting Mr. Boosie would read a paper on "The Manufacture of Paraffine," and Mr. Dow would exhibit a model "centrifugal railway." On the 23rd, at 4h. 40m., I found it was divided into near the centre of the disc measured 2' 54" by 1′ 44′′. were flashing on almost every side towards the zenith LETTERS TO THE EDITOR. of our correspondents. The EDITOR respectfully All communications should be addressed to the able to J. PASSMORE EDWARDS. "I would have every one write what he knows, and as much as he knows, but no more; and that not in this only, but in all other subjects: For such a person may have some particular knowledge and experience of the nature of such a person or such a fountain, that as to other things, knows no more than what everybody does, and yet to keep a clutter with this little pittance of his, will undertake to write the whole body of physicks: a vice frem whence great inconveniences derive their original."-Montaigne's Essays. In order to facilitate reference, correspondents when speaking of any Letter previously inserted will oblige by mentioning the number of the Letter, as well as the page on which it appears. SOLIDITY OF PLANETARY NUCLEI. "F.R.A.S." will understand that I am not inviting RICHARD A. PROCTOR. ERRATUM; AND AN APOLOGY. [632] SIR,-In my letter about sunspots, a sentence is rendered unintelligible by a slight erratum. I wrote-"Faculæ could be distinctly recognized in central regions of the disc (they were much more obvions near the limb in three regions)." This was printed "thos regions." Mea culpa, I imagine. I am reminded by the letter of "F.R.A.S." that "Amateur Astronomer" has asked me a question to which I have failed to reply. Perhaps this is the less important, as I really do not know even now what to say in answer. If about £3 will procure a small speculum, I should say certainly get one, and a prism and eyepiece to correspond; and build them up into a telescope, getting Browning's excellent "Plea for Reflectors," 1s., to learn what has to be done. RICHARD A. PROCTOR. I would clear away all the mounting, &c., from the top of the existing boiler,and fix a steam chest thereon, spherical or cylindrical as taste or necessity may as represented by the dotted lines-it may be made of this steam chest or dome, enclosing all the fire-tubes, require-carrying the conical uptake through the centre of course, as shown at A; also inserting a short tube b, as a connection between the boiler and steam chest, to carry off the wet steam from the boiler to the steam chest. supposed to separate itself from the surplus water in to deter any one from adopting the plan, it is but BOILER PRIMING.-LOCOMOTIVE DRIVING. [635] SIR,-"Bumpkin" (1. 591), suggests a plan in your last number, upon this subject, which has been under notice for some time. I do not think his way would answer, on account of the steam bubbles not being able to get away from under the wood or other material floating. If you think the following worthy of notice, I would ask you to insert it. It is a piece of sheet iron fastened above the water line in a double slanting position, as shown in the longitudinal section. No water would be able to reach the steampipe in the dome; the steam would have as free access as before, but would have to travel round between the ends of the boiler and those of the plate to roach the space above, and all water carried by it would be deposited on the plate and run back over the end. The above is merely a suggestion. (4859) There have been several reasons assigned for "Steam Rider's" uncomfortable ride. Mr. Tonkes appears to be nearer the mark, but the reason "Ox " gives I do not think will hold good, because the ratio of the area of the piston rod to that of the cylinder is so small as to be almost lost in the enormous pressure brought to bear upon the latter. Now I have a suggestion to make: had one side of the engine broken down leaving it running with one cylinder? I have ridden under such circumstances, and the result is a "series of jerks," as "Steam Rider" says, owing to the power being off the engine at the end of each stroke, and twice in one revolution. G. W. A. A SUGGESTION. [636] SIR,-The suggestion of "Husband" (letter 535) is not new. The same idea was proposed to me three or four years ago, and after some trouble I succeeded id making an instrument answering all requirements. A Mr. Pratt, of America, patented and exhibited in England (about 1867) an invention for the same purpose. A description was given in the Engineer. It seemed very complicated. The first attempt of the kind was by a Frenchman, who endeavoured to make an apparatus for the use of the blind. After having made a model to test the capabilities of my plan, I was induced by an abundance of friendly advice to forego giving up time and money for "such an uncertainty," which it was asserted would not pay. ОМЕО. THE QUADRATURE OF THE CIRCLE. [637] SIR,I am a new subscriber, and though but a self-taught working-man, I am a warm lover of science. Some few years ago, supposing that Mr. J. Smith was a sincere inquirer for truth, I wrote a letter and went about forty miles with it to endeavour to convince him of his error. He informed me he could do nothing with it that day, and that it was the old method, and so not applicable to his new method. I replied, that he ought to disprove my letter or cancel his work on the quadrature of the circle, as either the one or the other must be wrong. He has done neither. Knowing that Mr. Smith's book has misled many of the self-taught who were not sufficiently advanced to perceive the fallacy of its circular reasoning, I have pressed the substance of my letter to Mr. Smith into the following observations, should you deem them adaped to your young mathematical readers. I proceeded thus because Mr. Smith seemed to be well acquainted with the usual method of extracting the square root, and objected to the employment of series. The formula best adapted for computation, that I know of, is that by means of which Dr. Rutherford calculated the ratio of the circumference to the diameter to 400 places of decimals, viz.,-1 1 5 tan -11 +tan -11 = 4 tax (See his "Application of the Differential and Integral Calculus to find the Length of Curves.") MOUNTING OBJECTS WITHOUT HEAT. [638] SIR,-Will you allow me to ask Mr. W. White, of Monmouth, how he manages to mount microscopic objects in Canada balsam without heat? At p. 27, in his interesting essay on the Cricket, he says, "Don't apply heat at all whilst mounting. Never mind what the books say." Perhaps he would kindly oblige by giving us his method of mounting without heat, and wherein lies the secret. I find the balsam I use a hard resin, requiring heat before I can do anything with it. If I could use it cold I think I should not be pestered with air bubbles, &c. I have several bottles sent me containing diatomaceæ in water. They are fit for mounting, but I am at a loss to know how to proceed, perhaps one of your talented correspondents would oblige me. They are properly prepared for mounting, but I do not know if the water should be placed on the slide and allowed to evaporate, and afterwards a glass cover cemented on them, or how to manage. - JOHN JAMES. OIL FOR AIR-PUMP.-TO "INDUCTORIUM.' MUNITIONS OF WAR. M.R.C.S. [640] SIR,-Considering the great importance and interest at present attached to our munitions of war, as well as to those of other nations, may I take the liberty of asking some of the readers of the ENGLISH MECHANIC to give a description (with sketches, perhaps) of the different forms of projectiles now used? These, I need hardly say, include Greck fire, fire-balls, smoke-balls, light-balls, parachute lights, &c., &c., as well as the inventions of Martin, Shrapnell, Palliser, Mallet, Manby, Congreve, and others, and the contrivances and fusee arrangements of Boxer, Armstrong, Pitman, &c., besides several well-known foreign in [641] SIR,-Many thanks to Mr. Reveley (1. 551 and 1. 628) and "O. O." (1. 552) for their replies to my queries. I should like, if you are willing, to trouble them a little further, as I hardly understand their whole meaning. I can now supply other details, which would, if they had known them, perhaps have modified their opinions. When Mr. Reveley says that the supply-pipe should be laid nearly horizontal, and that its length should be from 50ft. to 60ft., does he mean that 30ft. should be thus laid, and the other 30ft. perpendicular, like the original plan of the elder Montgolfier? Is the one or two bends thus placed in the pipe for any other purpose than merely to add to the friction of pipe and help the recoil? Any one who has ever seriously thought on the hydraulic ram must see that recoil is the principle on which it works, and that a larger quantity of water falling a short distance and checked is equal to and will raise a smaller quantity a greater height. If friction is the object, then a longer drivepipe, because it gives this, should answer the same end. In this case it is laid at an incline of 1 in 4, and measures about 110ft. When you put your hand on top of pipe you feel a slight recoil, but the water in cistern is quite steady and well supplied, showing there is little waste of power, and the result proves this. Its ordinary work is, for 650 gallons per hour wasted, there are 195 gallons raised, at 121 strokes per minute, or with 98 strokes per minute 390 gallons per hour are raised in a steady regular stream while the air remains. As the snift valve opens every stroke and draws apparently very well, I think we must look to occasions within the past three years it has stopped by some other cause for the absorption. On two different ask the question, if the difficulty of regulating the air Should there be one or two THE FLUTE. [642] SIR,-Perhaps you and your readers have had enough of the flute controversy; yet I cannot refrain from saying a word in refutation of C. Devant's (1. 570) unfounded strictures upon that (if well played) sweet-toned instrument. He says the composers of the present day despise it; how is it then we find it in every orchestra ? Really the musical taste of the public must be fading, or they would not tolerate such "snorting, spitting" abortion as "C. D." has unearthed. He cannot have heard the late R. S. Pratten, Richardson, or others I could name, who have made their mark in the flute world. Again, why have poets and writers so often spoken of "flute-like voices " and tones" issuing from the lips of their heroes and heroines, if they amounted to nothing more than "tootletooing"? a 66 I infer that our friend must hold a prejudiced opinion from having been ear-tortured by some struggling tyro on the old German flute, and not having had the treat of hearing a professor discourse upon an instrument such as Pratten's perfected, which has been a source of intense eujoyment to thousands of delighted listeners. J. H. L. THE VIOLIN. [643] SIR,-In looking over some back numbers of the ENGLISH MECHANIC, I found with pleasure that the subject of violin construction had excited some interest, and received much investigation, yet I did not discover that an easy manner of improving an ordinary good instrument, and therefore increasing its value, is generally known. As I have done so to my violin with very marked success, I may speak with confidence of the improvement, which consists simply in placing a rod of light well-seasoned deal along the inside, abutting against the tail-post and the end of the neck. This bar, however, requires to be very neatly fitted and wider in the Now it is evident to any man, except Mr. Smith, that the nearest distance between any two points is a straight line; hence the arc of any circle is longer than the chord of the same arc. It is also clear that a greater area cannot be contained in a less; therefore the area of the inscribed polygon cannot be greater than the area of the circle circumscribing the polygon. The chord of an arc is equal twice the sine of half Let a be an angle less than 45°, and radius of circle/ having too much air, but we cannot get it to repeat river to have a current of two miles an hour, find the *1305262, which multiplied by 2 gives 2610524 for side of polygon of 24 sides or chord of 15. Multiplying by 24 we get 6.2652576 = perimeter of polygon of 24 sides. If in finding sin 15 the roots were extracted correctly to 14 places of decimals, this last result must be true to about 6 places; and, as the arc is greater than its chord, the circumference of the circle circumscribing the polygon must be greater than 6-2652576. But according to Mr. Smith's theory it would be only 6.25, which is impossible. And finding the area of this inscribed polygon of 24 sides, it is found to be greater than what Mr. Smith declares the area of its circumscribed circle to be, which also is impossible. So Mr. Smith's theory fails. Wern Mill, Ysccifiog. J. JONES. this so as to regulate the supply. Again, "O. Ö." says that a 2in. rising main is too large, because the pressure to be overcome at each pulsation of the ram is too intense. Now the pipe is taken off the air-vessel by a connection having hole through a yard or so of lin. lead pipe into 2in. main; water pressing equally in every direction, the weight in vessel will be the same with any size of pipe, and as the friction must be considerably less in a large 2in. pipe than in a small one, the larger body of water moving more slowly, the pressure in air-vessel ought to be relieved quicker, and therefore have the opposite effect to that which I suppose "O. O." to mean. In a private inquiry I made about a ram which has a fall of 16ft. with 4in. drive-pipe, raising water 280ft. through 2in. main, about 3,000 gallons in twenty-four hours, the owner says the air-vessel holds one gallon more than is required, and should be let out every third day or twice a week. Now too much air and no work is as bad as too little and straining the machine. This is the reason, Mr. "A boat's crew row 3 miles down a river and back Before committing an error on a large scale I must Enspend operations in that direction until he has favoured us. Can I not connect the two elements by a fine iron wire or the like, when not using the battery, to prevent the action he describes ? It has been proposed to combine with each cell of a Daniell's a supplementary cell; having a copper positive element and a platinum negative, connecting together the coppers of the two cells. It is presumed that the sulphate of copper solution will become saturated in one, as it is exhausted in the other: the copper in the second dissolving as fast as it is deposited in the first. To recharge the battery exchange the two porous cells with their contents, the current going in the other direction, depositing the copper upon the stripped plate that is in the saturated solution, and dissolving the deposited metal in the exhausted solution. Will "Sigma " kindly inform me if there is any advantage in this arrangement, or if it is founded upon a fallacy? In letter 601, p. 110, "if r be less than the reciprocal if 2" should evidently be, "if r be less than the reciprocal of 2 #," W. H. COFFIN. MR. S. A. VARLEY'S PAPER. [646] SIR,-In a paper read by Mr. S. A. Varley before the Mathematical and Physical Science Section of the British Association (a condensed report of which appears in your issue of Sept. 30th, 1870), Mr. Varley states that not a single case of a coil wire being fused has occurred on circuits protected by a bridge. Three cases, but three only, have occurred where the pointed metallic conductors have been connected together under the influence of discharge, the coils being uninjured." As this statement has been made so publicly, will you allow me, through the medium of your journal, to record the following faults in these coils which have come under my notice since the transfer of the telegraphs to the state? In one case the coil wire was completely fused, although it was protected by a bridge. In another case the metallic conductors of the bridge were in contact, the coils being thus cut out of circuit; and in several cases the magnets outside the coils have been demagnetized, thus seriously interrupting the working, as bar magnets cannot be so readily magnatized as needles. Each case mentioned above was after a thunderstorm. As it is not at all probable that faults in these coils have been restricted to those which have come directly under my notice, it would appear that little practical advantage has been gained by their introduction, more specially as during the time to which I refer, I have no record of a serious fault, such as the above-mentioned, having occurred in the old style of coils. J. W. W. WINDMILLS. 647] SIR,-Seeing wind power forms a subject for discussion in your columns, I beg to offer a short comparison between the horizontal and vertical systems, leaving your readers to draw their own conclusions on the subject. With Firstly. In a vertical mill the whole of the sails are constantly exposed to the full force of the wind. a horizontal mill it is almost impossbile for more than half the sails to operate at the same time, and most of those acting in a very imperfect manner, because they cannot all be at right angles to the wind at the same moment. Secondly. The sails of a vertical mill have their angles varying according to their distance from the centre of motion, so that every portion of a sail does a fair amount of work. The horizontal mill has no similar arrangement, and although the sails may be said to move in a line with the wind, their velocity measured on that line is continually varying. Thirdly. The sails of a vertical mill intercept most of the wind comprised within the circle which they deseribe. A horizontal mill is entirely dependent upon the amount of sail which it can spread. Fourthly. The sails of a vertical mill move in what may be considered as still air, though at a speed greater than the (wind. The sails of a horizontal mill have to be dragged back edge to wind at the speed of the wind the speed of the machine. It is to be remembered that the pressure of the wind is as the square of its velocity. Lastly. The sails of a vertical mill are simple and easy to make. The sails of a horizontal one are complicated and expensive. J. D. YORK. SUGAR MANUFACTURE. [648] SIR,-I regret that I cannot give to "Esperance" the result of experience wita sugar mills constracted as described by him, viz., rollers without Hanges working against planed headstocks. But I can most unhesitatingly express my entire agreement with his view and condemnation of the plan, not so much from fear of the probability of trash" getting between the rolls and headstocks and so causing a jam," as from the friction which must ensue between the canes and the headstocks, which flanges entirely obviate, and the very great chance which exists of friction to an unknown amount between the rolls themselves and the headstocks if the strains on the mill should, as is by no means unlikely, cause the slightest derangement in the position of these nicely-adjusted parts. Common sense alone is sufficient to show that in machinery of the class of sugar mills, subjected as these are to enormous and unequal strains, with the most reckless of feeding, accurate or close fitting in any but the actual working parts can be of no benefit and may prove an unmixed reil. Indeed there would seem to be but one object in the planing and facing spoken of, viz., that of enhancing the first cost of the mill, and of rendering repairs and consequent resort to the manufacturer more probable and more frequent (not to the advantage of the proprietor). DEAFNESS. tion addressed to themselves. J. B. PRIMUS. v2 × 7 + 50 d Then h= which reads thus: the 2500 dj velocity multiplied by the length of the pipe, plus fifty head of water is equal to the square of the times the diameter, and divided by 2500 times the diameter. Applying this rule to the case in question, the proceeding is this. 15 gallons per minute, passing through a pipe 2in. diameter, must have a velocity of 1-83ft. per second, which call r. Then d = 2in. = •167ft., and 1 in the first case = 60ft., and in the second 100ft. v2 x 1 + 50 d 68 × 8:35 Case 1. h = = '55ft. 2500 d 108 × 3:35 417 [649] SIR,-There does not appear to me to be any class of persons more deserving of sympathy, or who get less, than the deaf. No one thinks anything of ridiculing or cheating a deaf person; they are fair game for all sorts of swindles, in consequence of their perceptions being less acute than those of other people; those of the deaf are comparatively deadened. The Case 2. h = and whereas the perceptions of the blind are quickened blind meet with sympathy and help, but the deaf may go to the for aught any one cares for them; their affliction is only laughed at, especially when they misconceive-as they are prone to do-conversaThe hearing of the blind is quickened in an eminent degree, as well as all their other faculties; whilst the deaf, on the other hand, are blind to transactions taking place almost under their noses. All intellectual enjoyment is denied them, except reading and writing. Society is closed to them, nor can they compete for the prizes of professional life, either as doctors, lawyers, or clergymen; and as to becoming M.P.'s, or entering the army or navy, they might just as well strive for the premiership; whilst their life is one of constant privation of all the pleasures which others enjoy. In most cases an infernal noise is eternally ringing in their heads, to which the rushing of a train through a tunnel is but a faint comparison, and that of such a nature that if any ordinary person were to suffer for a week, it would drive him either to madness or suicide. AS DEAF AS A POST. CASK GAUGING. [650] SIR,-On examination of several works on mensuration, including those by Chambers and Ingram, it occurs to me that some of the rules given for caskgauging are extremely faulty, and calculated to mislead those who use them for ullaging or determining the contents of casks. to do a little business in this branch of The writer of this note, having sometimes occasion practical mathematics," would feel obliged if some one of your intelligent correspondents will kindly suggest a few practical rules which will determine the ullage and contents of casks with more exactitude than those at present in use. Some of the objectionable rules may be briefly stated here :-and 1. the common rule for ullaging a lying cask (v. Leadbetter's "Royal Gauger," Chambers' Practical Mathematics," &c.) The given formula are FRICTION OF WATER IN PIPES. [651] SIR, The question of " A Working Engineer" No. 541, on page 84, may be answered in this way. It is a law of hydraulics that the resistance of friction to water passing through a pipe of given diameter with a given velocity, increases with, and in the same ratio as, the length of the pipe. The resistance, therefore, due to the length of the pipes he mentions is as 100 to 60, or as 5 to 3. The measure of this resistance is usually called "head of water to overcome friction," and is ascertained in any particular case by the following formula. There are other formule, but this one will illustrate the case; it is given by Tredgold in his "Tracts on Hydraulics," and is quoted from Eytelwein. Let v = the velocity of the water through the pipe in feet per second. 417 = .87ft. So that the resistance of friction in the two cases is as 55 to 87. These are the comparative resistances due to the lengths merely; but a more serious consideration in the second case is the resistance of the six quick bends of 90 each. Weisbach has given a formula by which to calculate this resistance; but "A Working Engineer" asks for plain arithmetical rules. Well, if we turn to Dr. John Robison's "Mechanical Philosophy," under the head of "Waterworks," and in the section on Forcing Pumps, we find it stated that "the change of direction requires an addition of force to what is necessary for merely propelling the water through the pipe; it varies according to the abruptWhen a pipe is bent to a right angle, ness of the turn. without any curvature or rounding, the velocity is diminished about one-eighteenth, which would augment the head of water about one-ninth." According to this, if each right-angled bend augments the head of water necessary to overcome friction by 1-9th, 6 of them would augment it by, or g, which is, in effect, that whatever the resistance of friction may be in a straight pipe of any given length, the addition of 6 bends in it of 90° each will augment the resistance by two-thirds, or 66 per cent. It has been shown that the resistance in the second case is augmented by the increased length from 55 to 87, which is about 58 per cent.; and if we add the resistance due to the bends, we shall have a total augmentation of 124 per cent.; or in other words, the resistance in the second case is more than double that in the first. C. S. 6 THE ZODIACAL LIGHT. [652] SIR, It is with reluctance I presume to advance an opinion respecting the causes of this light, and the task would not have been undertaken if the argument against its terrestrial origin had been unanswerable; as, supposing it to be a phenomenon of the earth's atmosphere, and the denser portion of illuminated air is at the ecliptic, I cannot perceive how an observer should see the light vertically above him at any station north or south of this line. Again, as our atmosphere is not luminous, except under solar action, the tongue-shaped aspect of this light is accounted for by the consideration of the gradual diminution towards the zenith of the sun's influence. I apprehend, however, the subject will be better understood if a kindred phenomenon is previously investigated, giving, first, a glance at the nature and cause of light. will dispute the conclusion that it is occasioned by the I think no one conversant with luminous radiation, vibration of universal force. The transmission of solar light has no known limit; therefore, the vibrating power must be boundless. As a beam of ordinary light is of a compound character, its various rays being unequally refrangible, of several colours, and lengths of waves of vibration; and as the most refined experiment has failed in changing any one of them, it follows, the different rays, being unconvertible-must represent the vibrations of distinct forces. light invariably accompanies the volumetric contraction of elementary matter, but never its decomposition and expansion, and as the luminous waves are radiated from the contracting substance outwardly in every direction, it follows the vibrating forces must be expansive. Again, as By the theory described in letter 573, p. 89, the sun shaped mass of nebulous matter. is regarded as the condensing centre of a vast lenticularIt rotates upon its axis because the contractive power has converted a great portion of the force exerted upon it by expansion into this motion. It is surrounded by a luminous atmosphere, because its contractive force suffices to effect a continual condensation, and precipitation of the dense nebulous matter surrounding it; and by the joint effect of contraction and centrifugal force, the whole mass, with its contents, follows the direction of its axial motion. Suppose a comet, traversing space with cosmical velocity, enters the mass of nebulous matter surrounding the sun, the effect of solar radiation will evidently be proportionate to its chemical constitution. If formed of unstable materials it will combine with the nebulous matter producing light; and the intensity of the chemical action increasing as its distance from the sun diminishes, the comet will enter into violent combustion, Now it projects a long tail into space in a direction opposite to the sun, and the reason appears in both being condensing centres: a chemical combina. tion, and condensation of the nebulous matter being precipitated along the line of united action of sun and comet. It is the same with the earth. Although far more that of the sun, hence the "Zodiacal Light," the sub- AN INEXPENSIVE LATHE. [653] SIR,-There have been at various times illustrations in the ENGLISH MECHANIC of lathes of varions constructions, but they have all been of a price that frightens any one, save those with a long pocket, and I are sorry to say that a long pocket seldom accompanies the love of mechanical and scientific pursuits, and makers, as a rule, either don't or won't know this. How is it that I can buy a cotton loom for £5 or £6, and any little bit of lathe costs such a lot? Herewith I inclose a photograph of a lathe, lately purchased by a friend that lives near me, and I have often used it, and can speak well of its capabilities for both wood and iron turning. The foot headstock is cast in one with the bed'; by this, the cone on the spindle is a good diameter, so the strap sticks well; the large speed of the cone is drilled so as to answer the purpose of a dividing plate, with "SIGMA'S" SUGGESTION. [654] SIR,-I think the suggestion of "Sigma's," [655] doing in ASTRONOMICAL DIAGRAMS. Can we not all remember diagrams What would be thought of any zoolo- With Mr. Proctor's admirable ex- [656] two rows of holes, 20 and 25, very useful numbers for W. T. C. JOHN BROWNING. RAISING WATER (4492). diately beneath the working wheel. The ends of the chain, passing over the wheel, lead down through holes PLAN 栅 in the arms of the stay, as shown by the small black squares in the plan. The upper side of these arms and of one portion of the stay (that towards the driving shaft) has a fair surface, on which slides the piece h, whose arms, i i, bear against the hollow shaft of d d There are also two arms worked on hat right angles to it, resting on the arms of the stay. The movement of moves the wheels d d, thereby reversing the gear. What is required, therefore, is to move exactly as one bucket is emptied, thus reversing the motion, and retain it in that position until the other bucket rises to be emptied, and as that is emptied, h to return to its original position. This is accomplished as follows: -The bucket is hung on an iron rod, which has a wedge worked on the face of it, as shown at k. The chain is secured to the end of the rod, k. The large end of the wedge is in breadth equal to the necessary throw of h h, being in the position shown. As the bucket which is shown rises, the wedge will drive h across, thus moving d d. Now that h has been shifted and motion reversed it is necessary to secure h until the other bucket is empty, h is therefore secured by a pawl plate falling on its arm, which has notches to fit, the distance between the notches being equal to the throw of h. The paw! plate, which in this case secures h, is removed, and shown by itself 1, thus exposing the arm of h, on which it would fall. When his in either extreme position, there is room enough between the chain and the arm of h, to allow the thin end of the wedge to pass and lift the pawl plate before the wedge acts on h, h is driven over and the pawl plate on the opposite side falls and secures it. On the front of the bucket is a kind of handle, which as the bucket rises catches in a hook on the side of the trough, cants the bucket, and the water is carried off by the trough. I think the method is now explained in every particular, and leave it for "A. C. G." to say whether it is what the circumstances of the case require: I think it is. It is really a simple piece of mechanism that cannot well get out of order, and entirely self-acting, for when the honest donkey is put on the treadmill a bucket rises, is emptied, the motion reversed, the opposite bucket rises, is emptied, and so on continuously. The sketch is not done to any particular scale, the parts are put together as most convenient. Wishing all success to our Scientific Mutual Improvement Journal, I must conclude.-PSI. CORRELATION OF FORCE. [657] SIR,-As Mr. Proctor, No. 580, p. 105, requests the expression of my opinion as to the state of modern knowledge of the nature of forces, I repeat what I have often stated before; of the ultimate nature of forces, or of the causes of their operations, in fact, to use the abstract term, of their essence, our knowledge is entirely described by one word-nothing. We have not yet got over the old metaphysical stumblingblock, the question whether there really is such a thing as matter, or whether there exist actual forces. All we can deal with, all that any one will profess who really has anything beyond a very superficial, and, therefore, commonly enough, a very presumptuous knowledge, is a certain degree of information as to the external facts and operations, and a more or less wellbased idea as to the process by which these are effected. As to heat, it is pretty certain, and the whole scientific world now admits it, that it is a "mode of motion," probably vibratory, of the atoms of matter; but no one has yet shown, or even given us a tolerably sufficient guess, as to how the externally perceptible motion of sensible heat passes into the self-contained form known as latent heat; still less does any one as yet know how (I mean by what exact process) heat is related to chemical affinity, or why the actions ascribed to affinity are always attended with gain or loss of heat. I may venture (by exercising the faculty of imagination lately and justly lauded by Tyndall) to suggest that affinity is probably a function of wave length similar to harmony in music, and may yet be traced out by mathematical considerations from the absorption effects of different bodies in the spectroscope; still it is a guess. So with electricity. There is a very general feeling that it is also a mode of motion, but of what nature is much less certain than that of heat even. My papers originated in the desire to set forth certain ideas of stituting electricity; but supposing my theory were my own as to the nature of the mode of motion conever established, which it is not, we should still be as far as ever from knowing the cause which is at the foundation of these and other motions. In fact, each step by which we advance the bound of our knowledge only shows us more plainly that there |