the blade of the bradawl in such a manner that, WARMING CARRIAGES.-A new method of warming first-class carriages in express trains has machinery constantly exposed to friction. The grease thus obtained forms an excellent tallow, burning with a clear, brilliant, and what is infinitely more to the purpose, a white light, and at the same time emitting not a trace of any unpleasant odour, or of the ordinary disagreeable accompaniment of combustion-smoke."Notes and Queries on China and Japan." EXHIBITION OF FANS,-At the South Kensington Museum there has been opened to the public an The exhibition is a part of the exhibition of fans. art instruction of women. To promote this object, scheme of the Department of Science and Art for the the Deparment offered prizes in competition for fans painted by the students in the female schools of art in 1868, and again in 1869. The fan-mount to which in the first of these years the chief prize was awarded, is included in this exhibition, and it is intended to continue the competition. Her Majesty also purposes to offer a fan prize for competition at the International Exhibition of 1871. The Society of Arts has also offered its gold medal (of the value of 21 guineas) for Guest and Baroness Meyer de Rothschild have each the second-best fan exhibited. The Lady Cornelia offered a prize of £10 for the two next best fans. sum of £50 will be awarded and spent in various (3965.)-ORGANS.-Will the "Harmonious Blacksmith," Adept," or any of your organised body of contributors give me some information on the following subject:- When my organ was built some years since, funds being rather low, about six or seven of the bottom keys in the swell were left minus any pipes. A few months ago I consulted a first-class organ builder on the subject of having pipes attached Ho examined it, and informed me that the swell box had just been made to encase what pipes there is in, and no more; and that if I wanted pipes attaching they would have to be placed outside the case, a piece of business my swellish pride objects to. Will any trother reader (or sister either) give me their kind suggestion ?-THE HARMONIOUS COTTON SPINNER. [36]-TABLES WITHOUT DECIMALS.-I am of opinion that for certain practical and common purposes all tables which cau admit of figures-without minute decimals-would be a boon to numbers of working mechanics and others not having the power of making calculations; and I know of no medium CULTLY COMBUSTIBLE, AND FOR PRESERV equal to the ENGLISH MECHANIC to start the system. commends the following:-The wood, which must not Will any brother reader kindly arrange a table-free be planed, is placed for 24 hours in a liquid composed from decimals-giving the quantities of water, pounds, ounces, and parts of ounces (of course avoir- of 1 part of concentrated silicate of potassa and 3 of dupois), required to condense a cubic foot of steam, so pure water. After having been removed from this amounts by the Science aud Art Department, for fans as to produce a practical working vacuum, the steam liquid, and dried for several days, the wood is again produced by female students of the schools of art in to increase from common atmospheric pressure to 1lb. the United Kingdom. Among the more curious of the per square inch, up to 101b., or upwards, with size of is a landscape and figures embroidered in silk. fans exhibited is one dated 1650, the mount of which of the carving of the mounts is exceedingly delicate A fan, one of the wedding presents of the Empress of the French, is especially noticeable for its display of fine open cutting in so brittle a material as mother-o'pearl. Some of the fans possess historic interest, two or three being associated with the unfortunate Marie Antoinette. The Queen contributes sixteen examples; the Empress of the French, thirty-five; and the Princess of Wales, Princess Christian, and Madame la Comtesse de Paris, are among the contributors. condenser?-R.W. in [8967.]-MAGNETIC NEEDLE.-Will any of your subscribers answer me this question:-Supposing I have two magnetic needles centered, one strongly magnetised and the other only falutly so, from which ought I to get greatest deflection, placing each in suecessien in the same coil-Onra [3968.]-KILN.-Will one of your correspondents oblige me with a description of a good kiln for burning lime, and state the proportion of coal used to lime burnt, also the quantity burned per day? A sketch would be useful. Is there any good practical book on the subject?-L. M. [3969.]-COPPER BOILER.-Can any of my brother readers kindly inform me of the most efficient design of copper boiler to drive an iron boat 66 inches long by 6 inches beam, the engines of which are two cylinders, each 14 inch bore and 18 inch stroke; and what would be the best form of apparatus and fuel for firing same. The boat is 6 inches deep ?-0. G. [3970.]—FOOD FOR COWS.-Will any reader tell me how to steam food for cows; to do fifty bushels at once. Would it be cheaper to have an iron tank or brick and cement tank?-R.R. of [3971.]-DISPLACEMENT OF SHIPS.-Will any our correspondents be so kind as to give me a proper way to find the displacement of a ship? I have not given any dimensions, but those that can do it, can take a length, breadth, and depth for themselves. I know that it is a difficult problem, but surely there is one amongst our talented brothers that can assist me.-G. B. D. USEFUL AND SCIENTIFIC NOTES. HACKNEY SCIENTIFIC ASSO CIATION.-Mr. H. W. Emon, the Hon. Sec. of this Institution has sent us a report of its third annual meeting just held, from which we gather that the institution is flourishing. The number of members was actually twice as great as at the commencement; the papers, &c., read had been more interesting and numerous than on any previous occasion, and the library, which had only been commenced this year, already comprised many valuable works. The conversazione, held at the commencement of the session, was attended by a much larger number than was expected. It was announced that during the summer months excursions would be organised to places of scientific interest, also to the various public museums. METHOD FOR RENDERING WOOD DIFFI- soaked in this liquid, and, after having been again SOME HINTS ABOUT SCREWS.-Where screws CHANGES IN FISHES.-In the American Natu- A Some The SCRAPING SLIDE VALVES.-Mr. W. P Cowan, of Brooklyn, New York, writes to the "Scientific American to the effect that few workmen know how to scrape properly. He says:-I have always found the scraper works best after a smooth file; everything should be finished with the smooth file previous to the scraper being used. I have seen many workmen leave too much to be done by the scraper. Now that is a gross mistake; every article ought to be fitted as well as possible before being touched by a scraper; otherwise a bad job is almost certain to be the result. scraper should always be used obliquely to the file marks, never across, at any rate. Nothing makes a better scraper for wrought aud cast iron than a taper saw file, and for brass a flat scraper must be used if good work is wanted; say about lin. broad and 3-32in. thick. A saw file scraper is too keen for brass. In all railway shops in the north of England scraping is much used, and with the best results. We always scraped slide valves, motion bars and blocks, and axle boxes. It is certainly a very unworkmanlike way of turning out a slide valve and leaving it to work itself tight. It is tantamount to saying it can't be made tight. Most of the first-class marine engine builders in Great Britain scrape valves, &c. In one case last year it was tried to do away with the scraper on a pair of large valves,; but on the trial trip the valves got cut up awfully, so scraping is considered a necessity. GRAFTING IN CHINA.-A very peculiar method shoots of the chrysanthemum are inserted into the of grafting is practised in China. In spring the young cision, cross shaped, in the stem of the latter, and stalk of the aia plant (wormwood ?), by making an inbinding the two tightly together with a piece of past or hemp. After the incision has been properly bandaged; a flower-pot is put over it, bottom downwards, the plant passing through the hole in the pot, which does under it, about six inches high. Earth is then put into not rest on the ground, but upon four bricks placed the pot, and the plants gradually unite, taking root at the same time in the pot. As soon as the chrysanthemum flowers, the stem of the ai is severed immediately under the pot, and the whole is removed from the nursery to the garden or verandah. The grafting strengthens" the chrysanthemum, which would otherwise produce but The a very poor flower. method is most ingenious, and the plants seem to A NEW PROJECTILE.-Captain Ericsson announces, in a communication to the American Army and thought them quito distinct: and he says they have Nary Journal, that he has perfected a system of sub- changed considerably, but only in colour, during the unite very readily.-Notes and Queries on China aud last ten years. marine attack by which he can destroy the largest ironclads ever built. The resistance of the water is so great that explosive projectiles have always proved failures hitherto when designed to strike below the water-line. Captain Ericsson is confident that he has devised a projectile which will overcome the difficulty caused by this resistance. It is an elongated shell, charged with 3001b. of dynamite, and shot from a 15in. gun, at such an elevation as to enter the water near the hostile vessel, and strike the hull anywhere below the water-line. It is fitted with a percussion cap, which explodes upon very slight impact against the hull, so that the velocity of the shell when it reaches its destination need not be high. The gun is carried on a swift armoured boat, protected by a turret. Captain Ericsson intends to make a formal offer to test this invention. He is ready to fit out, at his own cost and risk, a fast screw vessel, with two 15in. guns of the kind described, if somebody else will furnish the ironclads to be experimented upon. In the politest terms he does this country the honour to single out the new British aclad Devastation as one of the most splendid pecimens of an armoured war-vessel which can be produced, and challenges her to come out and encounter his torpedo. BRADAWLS-It is stated, remarks the Scientific Review, that there are but three bradawl makers in London, and a bradawl seems to offer such a small field for improvement that a patent would appear to be scarcely worth applying for; yet this is not the case. An improvement has been invented, which consists in making the busk in two pieces, one secured to the handle, and having thereon a tapped or otherwise formed upper part, made to fit in and correspond with the second piece, such second piece being a tapped or otherwise formed cap, furnished with an internal projecting collar or shoulder, both pieces being constructed to receive Japan. REFLECTED LIGHT.-A series of experiments with a novel form of apparatus for determining the amount of light reflected from metallic surfaces at different angles has shown Professor Rood that a mirror silvered by Liebig's process, using the silver side at an angle of 45 deg., reflects 91 per cent. of the light emitted by a flame, and from the glass side 78 per cent., while an amalgam mirror at the same angle reflects only 455 per cent. The apparatus and in thod employed will be found described in the "Journal of Gas Lighting, &c." It would be interesting to know the reflecting power of the beautiful platinised mirrors now coming into use. DEEP-SEA DREDGING.-The Admiralty have THE GREASE TREE.-In China there grows a tree known as the Grease Tree. It is said that large forests of this vegetable lubricant are to be found there, and they form the source of a considerable local traffic, This tree not very long ago was imported into India, and it is said that the experiment of cultivating it there has proved quite successful. In the Punjaub, and North-western provinces generally, it grows as rapidly and as vigorously as in its native soil, and there are already thousands of t ees on the government plantations yielding tons of seed, admirably adapted to a variety of commercial purposes. Dr. Jameson, a chemist in the Punjaub, has prepared hundredweights of grease from this particular tree, and has forwarded on trial a portion of it to the Punjaub Railway to have its qualities tested in a practical manner as lubricating material for those parts of dilute sulphuric acid in preventing colic. GLUE-The value of glue, that is, the amount of pure gelatine it may contain, may be determined by precipitating this body with pernitrate of mercu y, a standard solution of which tested with a kuown weight of pure gelatine may be employed. ANSWERS TO CORRESPONDENTS. All communications should be addressed to the EDITOR of the ENGLISH MECHANIC, 31, Tavistockstreet, Covent Garden, W.C. ADVERTISERS' TESTIMONIALS. Messrs. ASHWORTH, of Ashley-lane, Manchester, after advertising their patent "looped" portfolios in the ENGLISH MECHANIC a few times, say:-"Several hundred of these binders for the ENGLISH MECHANIC have already been sent out." CAUTION. Messrs. MOTTERSHEAD, Market-place, Manchester, say:"Having noticed in a recent number of the ENGLISH MECHANIC a caution about certain members of the long firm calling themselves "Claud & Co., Cheltenham," we send a line to say that we have been favoured with an order from these individuals, but, thanks to your notice, were on our guard. We sent them, as we usually do to strangers, an invoice, requesting a remittance before we sent the goods. Of course we have received no reply (since the 2nd April). We have since had an order from Parks & Co., Manchester Warehousemen, Alvington, Glo'ster, which we treated as above, with exactly the same result. We should judge from the writing that they are the same people. Perhaps another caution about them might be useful." THE following are initials, &c., of letters to hand up to Friday A. W. MARSHALL would oblige by sending the information for "Xanthos and "Cotton Clerk" to our pages for the benefit of others as well. Rev. E. KERNAN, with MS. complete to folio 173. E. SLATER, on Cotton Spinning, next week. PETER FIELDING,-We cannot forward trade circulars. A. TOLHAUSEN, with MS. on Materials, &c. POLSON.-Advertisements must be paid for. letter. J. T. B. (Chelmsford).-Thanks. As we have refused Mr. J. H. D.-Arrangements are being made to publish the J. B. W.-We cannot act as arbitrators. J. BARRY.-The fault is with the Post Office. W. T. J.-We can only express our sorrow that the ENGLISH ARTISAN will see it is an American invention. J. B. asks what he can do in return for the assistance he has R. W.-Anyone may ask for or communicate information COTTON SPINNING.-Several letters on this subject are post- THE INVENTOR. IN obedience to the suggestions of a number of readers, we have decided on appropriating a portion of our space to a condensed list of patents as nearly as possible up to the date of our issue. APPLICATIONS FOR LETTERS PATENT DURING THE 1408 J. L. Montefiore, 52, Kensington Gardens-square, im- 1411 J. H. Player, Birmingham, apparatus for the manufac 1412 H. B. Greenwood, Welwyn, Hertfordshire, apparatus 1415 B. Hunt, 1, Serle-street, Lincoln's-inn, improvements in 1417 B. Birnbaum, New Broad-street, London, an improved 1418 F. J. Cleaner, Red Lion-street, improvements in apparatus for moulding and stamping soap 1450 G. G. M. Hardingham, 28. Great George-street. Westminster. improvements in tobacco pipes and cigar holders 1430 A. Taylor. Lydbury, Salop, improvements in rocket projectiles for purposes of war 1461 T. Hodson, Manchester, improvements in the manufacture of piled fabrics 1402 T. J. Smith, 166, Fleet-street, an improved arrangement of apparatus for diminishing the friction of spindles, axles, and other similar rotating bodies.-A communication 1463 J. J. Denoual. New Cross, improvements in enveloping medicinal and other liquids 1484 D. C. Lowher. "Church-street, Warrington, improvements in wire ties for securing bales of hay, cotton, and other merchandise 1465 W. Barwell and G. B. Smith, Birmingham, improvements in securing the nuts of the screw bolts used in dsh jointing the rails of railways 1466 H. Osterkamp. Eschweilerpumpe, near Aix la Chapelle, Prussia, improved rock-drilling machine 1467 A. M. Silber, Wood-street. Cheapside, and F. White, Camberwell, improvements in apparatus for lighting and heating purposes firing with complete smoke combustion, &c. 1409 R. Harte, 42. Argyle-road, Kensington, improvements in means and apparatus for effecting aerial locomotion 1470 J. A. Ryke Van Den Bergh, Southsea, an improved sea messenger or receptacle to be used for receiving papers, parcels, and such like 1471 G. Simpson, Glasgow, improvements in machinery and arrangements for cutting or getting minerals 1472 T. H. Lloyd, Stockport, improvements in the construction and arrangement of valves 1473 W. Avery, Redditch, improvements in cases or receptacles for needles, pins, matches, pens, cards, stamps, photographs, cotton, and other similar articles 1474 P. Webley and T. W. Webley, Birmingham. improvements in breech-loading fire-arms 1475 E. E. Allen, 33, Pelham-place. Brompton. Improvement in the construction of tramways and in engines and carriages employed thereon 1476 F. J. Tellier. Paris, improvements in machinery for the manufacture of strings and cords 1477 H. Hind. and G. Wells, Nottingham, improvements in steam and other valves 1478 B. Perowne. Great Snoring. Norfolk. improvements in machinery for cutting turnips and other roots 1479 F. Milnes, Camden Town. improvements in apparatus for healthily exercising the human frame 1480 J. Macqueen, Manchester, certain improvements in carding engines 1451 W. E. Heath, 23, Camden-roud, improvements in cooling or refrigerating beer, liquors, or beverages 1483 H. A. Bonneville, 18, Chaussea d'Antin, Paris, a new and improved mode of manufacturing wooden floors and wainscots.--A communication 1483 H. A. Bonneville, 18, Chausee d'Antin, Paris, improvements in sewing machines.-A communication 1481 P. C. Evans, Brimscombe Mills, Gloucester, and H. J. H. King, Glasgow, improve nents in apparatus for feeding wool, cotton, or other fibrous materials 11485 M. Benson. Southampton-buildings, improvements in the mode of supplying lamps or lanterns with atmospheric air. -A communication 1188 A. Long, 32, Avlesbury-street, Walworth, improvements in means for rezulating the flow or controllin the supply of water or other fluids 1487 W. E. Newton, 66, Chancery-lane, improved machinery for grinding hand saws.-A communication 1488 A. Browne, 85, Gracechurch-street, improvements in screw propellers.-A communication 1489 J. Head, Middlesborough, improvements in setting horizontal stationary boilers 1490 W. R. Lake, Southampton-buildings, London, improvements in machinery for scouring, glossing, and otherwise 1419 B. Lawrence, Basinghall-street, an improved ink, or im-treating leather.-A communication 1420 T. G. Webb, Manchester, improvements in the manufac 112 G. Nelson, Liverpool, improvements in apparatus for 1423 T. P. Young, Bury, Lancaster, and J. Thomasson, Rad- 1425 J. Casthelaz, 19, Rue Saint Croix, Paris, improvements in 1426 J. G. Charlick, 4. Park-street, Dorset-square, improve- FIGURE OF THE EARTH.-Mr. Jas. Beardsley has written us T. J. O'CONNOR-The Philosophical Magazine is published J. S. W.- We cannot give the addresses. You might put E. HATCHIN. We know nothing of the party you mention. A COUNTRYMAN.-We cannot supply them; but they are such cases. THE Sixpenny Sale Column is the only place in which can appear queries sent by Staem, S. D. T., E. G., W. R., A. O. S., Beta. G. C.-It results from several causes-bad teeth, disordered stomach, consumption, &c., and can only be cured by consulting a medical man 1431 W. R. Lake, Southampton-buildings, London, improve. ments in looms for weaving.-A communication 1432 W. Brodie, Edinburgh, improvements in the construction of vehicles used on railways 1433 G. R. Turner, The Woods, Charmouth, improvements in winnowing or dressing machines 1434 F. Edwards, Nottingham, improvements in the manufacture or production of lace 1435 E. Peyton, Birmingham, improvements in the manufacture of welded iron or steel tubes 1433 E, Peyton, Birmingham, improvements in the manufacture of metallic bedsteads 1437 G. T. Bousfleld, Loughborough-park, Brixton, improve. ments in looms for weaving.-A communication 1438 A. M. Clark, 53. Chancery-lace. improvements in machines for manufacturing cigars.-A communication 1439 J. Stoart. 61, Saint James-road, Bermondsey, improve. ments in cleansing ships' bottoms 1440) J. Diggle, Radcliffe, Lancaster, and H. Booth, Pilkington improvements in looms 1441 B. C. Muzzall, Windsor, improvements in the construction of school furniture 1442 S. Baerlein, Manchester, improvements in doubling cotton 1413 J. Smithies and J. Smithies, improvements in the manufacture woven fabrics 1444 W. E. Gedge. 11, Wellington-street, Strand, improvements in steam engines.-A communication 1445 G. Zanni, Sidmouth-street, Gray's-inn-road, improvements in magneto-electric telegraphic apparatus 1446 J. A. Hopkinson, and J. Hopkinson, jun., Huddersfield improved means or apparatus for admitting and regulating the supply of air to steam boiler and other furnaces 1447 R. Oxiand, Compton Gifford, Plymouth, improvements in the manufacture of sulphuric acid 1448 G. W. Rendel, Elswick Works, Newcastle-on-Tyne, improvements in cartridges for ordnance 1440 R. Pitt, Newark Foundry, Bath, improvements in valves for drawing off water and other fluids A PRESSMAN.-See Reply 3907, in this number. number on the subject, and will probably bring answers to JEUNE HOMME.-Information on the subject appeared in last TOPSY TURVY.-An exceedingly silly question. A. G. PERRING.-See reply to Canto. H. 2. SAVORY.-Thanks for patterns. WM. CARPENTER-We really cannot afford space. J. R. T.-la due time. 1450 J. Schloss, 46, Cannon-street, London, improvements in fastenings applicable to purses and such like articles.-A com 1451 W. Rake. Southampton-buildings, London, imowe- 1453 J. Baird, sgow, improvements in treating oils 1454 J. P. Blake. Massachusetts, U.S.A., improvements in 1456 A. M. Clark. 53. Chancery-lane, improvements in ap- 1457 M. Giraud, Rue Sauzay, No. 22. Constantine, Algerie, 1491 W. R. Lake, Southampton-buildings. London, improve ments in machinery for sewing boots and shoes.-A communication 911492 T. A. de Carvalho, 1, Park-villas, High-road, Lee, improvements in ships and vessels 1493 M. Henry, 68, Fleet-street, an improved case holder or receptacle for matches.-A communication PATENTS SEALED. 3368 J. Bottomley, and S. Emsley, improvements in spinning fibrous substances 3376 H. A. Bonneville, a new and improved steam boiler supply cock.-A communication 3377 H. A. Bonneville, electro-metallurgy.-A communication 3378 H. A. Bonneville, improvements in electric batteries.A communication 3380 J. E. Croce-Spinelli, improvements in means and apparatus for propelling and steering vessels 3381 E. Round, an improved indicator for marking games of skill or chance 3334 A. Nairn, improvements in steam carriages for common roads 8389 A. McNeill, a safe for ships and other navigable vessels carrying mails, specie, and other valuables 3391 J. Fog, improvements in machinery for dressing flags and stone and other hard materials 3392 S, Cotton, improvements in machinery for preparing flax 3398 S. Chatwood and T. Sturgeon, mprovements in apparatus for forcing and drawing fluids and liquids 3401 W. C. Mann, improvements in the manufacture of hats 341 W. Pollitt, and W. J. Knowles, improvements in machinery for washing, wringing, mingling, churaing, and mixing fluids 3443 S. Perry, J. J. Perry, and L. H. Perry, improvements in boxes for holding various articles 3460 J. Wood, J. Wood, and W. H. Wood, improvements in ventilating hats or other coverings for the head 3748 W. Bennett, and J. Currall improvements in kitchen rances and fire-places or stoves $569 G. F. Logan, a new or improved means for utilising Waste heat 8779 G. Hamilton, improvements in the construction of steam boilers 151 . Whitehead, improvements in wool combing and drawing machinery 194 J. M. Plesner, improvements in apparatus for and in the treatment of liquid fuel 308 U. Kinzler and A. Keppler, improvements in propellers 630 J. O. Morrell, improvements in apparatus applicable to the treatment of refuse for sanitary purposes 74 J. J. Stevens, J. J. F. Stevens, and W. A. Stevens, animproved apparatus for working points and siguals on railways 918 C. Cotton, improvements in machinery for the manufacture of knitted fabrics 3400 3. Goddard and w. Finley, machinery for pill mass mixing and pill making 31. M. Felton, improvements in collars and cuffs 8417 D. Barker, improvements in the manufacture of varnish and varnish paints 318 J. Denis, improvements in the means of and machinery for producing pulp from wood 3422 . H. Barke, improvements in metallic barrels 3424 W. Perkins, improvements in fusees, matches, or other analogous articles. 3425 J. Combe, improvements in machinery for hackling flax and other fibrous substances 3127 J. Brunton, improvements in working and locking railway points and signals 3431 J. Pitt, J. Pitt, E. Pitt, and W. Pitt, improvements in machinery or apparatus for drilling, turning, or casting and shaping metals or other materials 3435 L Pochet, an improved apparatus for cutting or dress ing stone 3439 W. Cross, an improved manufacture of shawls 3441 S. Fox and J. Reffitt, improvements in machinery or apparatus for boring, turning, and polishing trouails and bobbins 3455 J. Edwards and J. Quin, improved means for preventing roller laps on roller ends of machines for carding cotton, woollen, flax, or any other fibrous material 3409 R. Milburn and T. Browning, improvements in drying machines suitable for drying ears of corn, grain, seeds, and other materials The English Mechanic AND MIRROR OF SCIENCE AND ART. For NOTICE. external boundaries of luminous surfaces which being incalculably more feeble than the intrinsic answer the description as far as one side of them splendour of stars of any considerable magnitude. is concerned. The surface itself mathematically I have, however, noticed a border round the limb represented by an infinite number of points, will of Venus, undoubtedly due to such a cause, and produce a luminous image composed of an in- in all probability it would he very conspicuous finite number of overlapping spurious discs; and round the sun, were it possible to view him withthe outer boundary which terminates that surface out such a darkening apparatus as must extinwill consist of the half of such an image of a line guish all such appendages. The knowledge of as has been described; the other half being of these facts serves to explain why the details of course merged in the general illumination of the planetary surfaces are frequently not so well disc. Every line being referable to an infinite made out with the largest apertures as we might number of points, and every surface to an infinite have beforehand expected. The amount of light OR years past the ENGLISH MECHANIC,though number of lines, and the image of a luminous may be sufficient to render the interference-rings professing to be published on each Friday point being strictly ascertainable as to character visible, which, overlapping each other throughout morning, has in reality been published on the pre- by the laws of optics, and determined as to the luminous area. must produce a certain magnitude by the experience of the best opti- amount of hazy indistinctness, or what is comeeding Monday. We have, therefore, been obliged cians, we have at length a clue which will guide monly termed a "glare." Hence there is often to go to press on Friday evenings, or a week before us through all the details of telescopic definition. a gain in the definition of minute details by the the nominal day of publication. As this arrange- which must be carefully borne in mind. The haze, and this may probably be the reason why There are, however, collateral considerations reduction of light through moonlight, twilight, or ment has occasioned no end of inconvenience to phenomenon is not only objective but subjective every telescope usually shows such details best correspondents and advertisers, it has been deter--that is, it depends not merely on the existence with a certain amount of power-namely, that of certain undulations, but in the capacity of the which without expanding the light to too great mined in future to go to press on Tuesday evenings, retina to appreciate them. Below a certain in- feebleness, reduces it so far as to render these and publish early on Friday mornings; in other tensity, varying considerably in different in- rings, and the resulting irradiation or glare, inwords, on and after the 8th of July next, the dividuals, the vibrations constituting light fail to sensible. produce any perceptible effect upon the organs of ENGLISH MECHANIC AND MIRROR OF SCIENCE vision; and the office of the telescope in many will be published at the same time as the widely- cases is, by collecting a greater number of these circulated London weekly papers. In order that vibrations, to produce the requisite intensity, and to strengthen the latent image till it excites the no inconvenience or disappointment may arise, retina to a sufficient degree. Thus, though the our readers will oblige us by informing their optical image of every star is theroretically surrounded with a considerable number of rings, ELECTRICITY-ITS THEORY, SOURCES, respective booksellers or newsagents of the con- in practice our eyes can only distinguish a few of templated alteration in the day of publication. them, even around the brightest stars, from the We beg also to inform our Subscribers that we diminish in magnitude, so the outer rings go rapid degradation of their light; and as the stars have purchased the copyright of Scientific Opi- successively out of sight. By the use of a larger nion, and that on the day mentioned the 8th proximo, that well known and high-class scientific publication will be incorporated with the ENGLISH MECHANIC. Scientific Opinion has a good staff of contributors and correspondents ;these, added to our own, will no doubt materially enhance the value of the ENGLISH MECHANIC. as we call up, store some of the lost rings, but adtion, and so to speak, the rings of the inferior magnitudes, so we bring into sight the central discs of innnmerable fainter stars, which were before imperceptible, and whose rings are still too feeble for our sight. And the same of course holds good with the external portions of the spurious discs which are in a similar way lost sight of, or brought into view, according to the visible telescopic brightness of the star. In every case, therefore, of a luminous telescopic image, the HINTS TO ASTRONOMICAL STUDENTS. theoretical result is modified by the receptive BY T. W. WEBB. (Continued from page 74.) Na previous paper we discussed at some length IN the nature of the images formed from luminous points by refraction on reflection, and the representation of stars by spurious discs, with their attendant rings. We will now proceed to extend our remarks to the consideration of the telescopic definition of lines and surfaces. The character of this, after what has been said, it will not be difficult to understand. As the real discs of the stars, from their extreme remoteness, approximate, so far as our sight is concerned, to mathematical points, so, for the same reason, the natural outlines and boundaries of heavenly bodies become sensibly mathematical lines. But the mathematical line may be considered as composed of an infinite number of mathematical points; and its telescopic representation will therefore be equivalent to an infinite number of spurious discs, each with its attendant series of rings. The resulting image, instead of being indefinitely and almost imperceptibly narrow, must have a sensible breadth equal to that of the spurions disc; and the edges of the infinitely overlapping rings wi produce as many narrow luminous borders on both sides of it as there are visible rings, each parallel to the bright band which forms the image of the line. Such is the natural result of what we have already attempted to explain; we have, however, no opportunity of exemplifying it in practice, there being no instance of a luminous object in the sky, at once, long enough, narrow enough, and bright enough. to form such a telescopic image. We have, how ever, in the limbs of the celestial bodies, the power of the eye, and the aperture of the instru- We are now in a position to understar.d why as that such an effect is imperceptible for the same We have thus pursued the subject of definition to a considerable extent. The different modes, however, in which telescopic vision may be effected will render a little further investigation necessary at a future opportunity. AND APPLICATION. BY J. T. SPRAGUE.* The next great class of electric gene- inventions. 131. GROVES's CELL.-This was the first devised of this class, and in most respects is the best, platinum being the negative metal, and nitric acid the oxidising agent. The form is not essential, but it is usually made with flat plates; the platinum in a flat and narrow porous vessel to reduce the quantity of acid to the least, the zinc being either in two plates connected together, or one plate bent so as to surround the porous vessel at a distance of about three eighths of an inch. Fig. 40 cylindrical porous jar, as in Fig. 41, which will serve as the type of this form. 133. CARBONS.-The employment of carbon is attended with some difficulties which call for attention here. Carbon is one of the most remarkable of the elements, possessing what is called "allotropic" forms, in which, though chemically the same thing, its physical properties are different, with different relations to heat, electricity, and light; such varieties are the diamond, charcoal, and graphite. It is this latter which is useful in electricity, either in its natural form of plumbago or black lead, or the artificial deposit of gas carbon. It must be clearly understood that this substance is not coke; coke is the solid residue left after distilling coal; the graphite comes from the gas, the rich hydrocarbons of which are decomposed by contact with the heated retort, on which they form a shell; it is, in fact, a great nuisance to the gas maker, as it arises from the destruction of the richest gas, injures the retorts, and wastes the heat; in the gasworks it is called "scurfing." The densest and hardest is the best for electrical use, and some which comes from abroad is far superior to anything our English cals produce; it should be almost non-absorbent, and ring like a metal when struck, and have a clear gray colour, not black. It is rather costly when good, simply because of the great difficulty of working it. Other substances will answer, such as the material of black lead crucibles, which is indeed made up for the purpose, The chief difficulty with carbon is making the connection with it; this is commonly done by simply fixing a clamp on it, in which case a piece of platinum ought to be interposed between the two surfaces. A better plan is to deposit copper on the upper part, and then solder the connection to it, as this gives continuous circuit ; the copper takes on it just as it would on a metal. There is one drawback to this, the same in fact which requires the platinum interposed in the first plan; the acid both creeps up the surface and soaks into the substance, and then acts on the copper and destroys the connection. I have devised a perfect remedy for this which I do not think has ever yet been published. Before use I thoroughly dry the carbon and mark on it the point to which the liquid will reach, and then moisten with water this part, and also the extreme top where the copper is to go; the intermediate part is then heated by a Bunsen's gas burner, and touched carefully with a piece of paraffin as long as it will absorb any, taking care none runs over the surfaces to be used; with care this intermediate portion may be thus thoroughly saturated with paraffin, which resists contact of liquids, and on which acids have no action; the copper is now deposited, and the connection fixed, and then the copper surface and top of the carbon is covered with a thick coat of paraffin, which serves as a complete protection. by one atom of acid would be different. The principal action which really occurs is the first and third combined, HNO3 + Hs becoming 2 Hg 0 + NO, and according to this, one atom of nitric acid is effective for one and a half equivalents of electrical action; or to express it practically, though not in the true chemical language, two-thirds of an atom is the equivalent. This action is however complicated with others, for the acid is even totally deoxidised and converted into ammonia to some slight extent. Owing to this and to the loss by evaporation or carrying away of acid by the escaping gases, and by leakage through the porous cell, the working equivalent or value of the acid can only be settled by actual experiment, and in addition to this, when we buy nitric acid we only get a solution of it varying very much in actual strengh. I therefore have calculated a table showing the properties of the acid at the various strengths; it is not prepared for analytical, but for practical use, and is based on Ure's tables. Column I. is the specific gravity as given by him; Column II. is the percentage of true acid HNOS U e's tables are based on the anhydride N, O, formerly regarded as the acid, but I have calculated the true acid from his figures. Column III. is the number of atoms of 63 grains weight contained in one lb weight; 'and Column IV. the number of those atoms in 1000 grains fluid measure; these two I have calculated from the percentage, and they will furnish every required information as to the work which acid of any strength is equal to. 28, is 2HNO3 + 3HO. This is the strength to which boiling brings both stronger and weaker acids and distils unchanged at 248° Fah., but is not, as sometimes stated, a definite hydrate, as it varies according to the pressure. 39 and thereabouts, is double aquafortis, and about 63 is single aquafortis. of 136. The following experiments will both illustrate the uses of the table and the actions of the battery. The acid used was pure, intended for analytical purposes, its specific gravity 13175 giving, by averages between No. 49 and 50 in the table, a value of 10-58 atoms per 1000 grains, or 5-29 for 500, the quantity used in the porous cell, which on the above theoretical considerations should furnish at two-thirds 7.93 equivalents; 3000 grains measure sulphuric acid solution were used in the outer cell equivalent to the consumption of 12 units of zinc, and a sheet of copper was arranged to receive a deposit of copper. The cell continued in action for nearly 7 hours, giving a deflection ranging between 679 to 55° and at last falling rapidly to 20°. There were deposited 8.64 units of copper, while 10-21 units of zinc were dissolved, showing a loss, by local action, of 1.57 units. I afterwards allowed the action to go on as long as any took place, but only 1-23 more of copper was deposited, and 3 of zinc dissolved, showing how much the local action increases towards the end; it was more than 14 per cent. beyond the 5 allowed in calculations for the simple cell: as to the nitric acid, 8-64 the true work is so near 7.93 that calculated as to show that the reaction described is the chief one and that the more perfect deoxidisation which may occur compensates for losses; however as it is not possible to work to near exhaustion as in this experiment, for practical purposes the atom should be taken as the equivalent instead of two-thirds. 137. It has been recommended to use salt instead of sulphuric acid, and the following trial was made under exactly the same conditions as the first; the current went up to 64° lasted 3 hours instead of 7 gave a deposit of copper 4:13 units and use of zinc 4.72 being a loss of oneeighth by local action. This proves, as might be expected, that the use of salt is bad economy, it takes no part in the reaction (so far as cost is concerned), except as a conductor, but the zinc is dissolved by the nitric acid transferred to it by electrolysis. 138. For practical use a much cheaper nitric acid may be obtained. Thus I use one of sp. gr. 1-4146 containing 76-4 atoms per lb., and costing threepence per lb., or '0393 of a penny per atom. Applying the results of the experiment to this value we have the cost of working nitric acid batteries thus: Extra local action 14 per cent. = '0066 Nitric acid-atom I. II. Specific Percentage Gravity. HNO3 Atoms per lb. 1 1-5210 100. 111-11 214 2 1.5000 92-978 103:31 21.5 1.4980 92.048 Cost of simple cell per unit -0471 70.000 77.78 15.78 15:50 76.44 15:29 67.874 78:34 14.65 134. Other materials have been employed, as lead or iron, platinised. Cast iron has been strongly advocated under the name of Callan's, or the Maynooth cell; a very few words will sum up their qualities. They are worthless. If any one wishes to lose his temper and his money he can use a cast iron battery, with some certainty 36 of success. They waste the acid frightfully, they boil over suddenly, in fact they do everything we 39 should wish not done, without having one redeeming quality to atone for their evils. 135. The relative merits of platinum and carbon depend on circumstances; the first is most expensive at first (especially as it is bad economy to use very thin sheet, which is a bad conductor, and soon becomes brittle and breaks up), but it gives a slightly higher force, and is preferable if the battery is to be much used. Still, for ordinary use the carbon answers every purpose, and is much more commonly employed. The actual conditions and expenses of working are the same with both, and the following remarks apply to both, though the experiments were actually made with a carbon plate. It is impossible to give an exact statement of the reactions which take place in the nitric acid cell, as they are continually varying with the strength of the acid. HNO3 may lose 1 atom of oxygen, becoming HNO2 nitrous acid, under one equivalent of action, which provides Hg to from H2O water; but one atom of hydrogen is equally able to take up one of oxygen together with the hydrogen of the acid; thus HNO3 + H becomes H2O + NO2; or the same reaction taking place with the residue (nitrous acid) of the first case HNO3 + H becomes H2O + NO. In each of these cases the work done electrically, 7.28 7:07 6-43 622 6.00 hydrate formert. 1, is the absolute theoretical acid, called the 1st 19, is 2INO hydrate. +2 0, formerly the 2nd Cost per unit = This shows an excess of cost of one-eighth by using salt, and this excess would increase according as the cost of nitric acid per lb. or per unit exceeded the figure given. Adding to the first figures enough to bring the cost up to practical working, or 1 atom of acid per unit 07990131 0930 as the cost per unit as compared with the other forms of battery. This is somewhat under that of Daniells, but that is capable of reduction by causing the copper to be deposited in useful forms, while this is at its lowest; the real drawback, however, to nitric acid batteries is the escape of nitrous gases, which are unwholesome and very injurious to all metallic substances; where these can be avoided, and the trouble attending its use is of little moment, the nitric acid cell is undoubtedly the most powerful and most advantageous source at present known from which to obtain a steady and powerful current. (To be con'inued.) ON STAR-GROUPING, STAR-DRIFT, AND Le Sueur, with the great reflector erected at Mel- families of satellites; we see the rings of Saturn, STAR-MIST.* (Concluded from page 247.) TURNING to of URNING to the subject of star-mist, under propose to deal but with a small proportion of the evidence I have collected to prove that none of the nebula are external galaxies. That evidence has indeed become exceedingly voluminous. I shall dwell, therefore, on three points only. First, as to the distribution of the nebul:They are not spread with any approach to uniformity over the heavens, but are gathered into streams and clusters. The one great law which characterises their distribution is an avoidance of the Milky Way and its neighbourhood. This peculiarity has strangely enough been regarded by astronomers as showing that there is no association between the nebula and the sidereal system. They have forgotton that marked contrast is as clear a sign of association as marked resemblance, and has always been so regarded by logicians. Secondly, there are in the southern heavens two well-marked streams of nebule. Each of these streams is associated with an equally wellmarked stream of stars. Each intermixed stream directs its course towards a Magellanic Cloud, one towards the Nubecula Minor, the other to wards the Nubecula Major. To these great clusters they flow, like rivers towards some mighty lake. And within these clusters, which are doubt less roughly spherical in form, there are found intermixed in wonderful profusion, stars, star clusters, and all the orders of nebula. Can these coincidences be regarded as accidental? And if not accidental, is not the lesson they clearly teach us this, that nebulae form but portions of the sidereal system, associating themselves with stars on terms of equality (if one may so speak), even if single stars be not more important objects in the scale of creation, than these nebulous masses, which have been so long regarded as equalling, if not outvying, the sidereal system itself in extent ? The third point to which I wish to invite attention is the way in which in many nebula stars of considerable relative brightness, and belonging obviously to the sidereal system, are so associated with nebulous masses as to leave no doubt what ever that these masses really cling around them. The association is in many instances far too marked to be regarded as the effect of accident. Amongst other instancest may be cited the nebula round the stars c and c in Orion. In this object two remarkable nebulous nodules centrally surround two double stars. Admitting the association here to be real (and no other explanation can reasonably be admitted), we are led to interesting conclusions respecting the whole of that wonderful nebulous region which surrounds the sword of Orion. We are led to believe that the other nebule in that region are really associated with the fixed stars there; that it is not a mere coincidence, for instance, that the middle star in the belt of Orion is involved in nebula, or that the lowest star of the sword is similarly circumstanced. It is a legitimate inference from the evidence that all the nebule in this region belong to one great nebulous group, which extends its branches to these stars. As a mighty hand this nebulous region seems to gather the stars here into close association, showing us in a way there is no misinterpreting, that these stars form one system. The nebula round the strange variable star, Eta Argûs, is another remarkable instance of this sort. More than two years ago I ventured to make two predictions about this object. The first was a tolerably safe one. I expressed my belief that the nebula would be found to be gaseous. After Mr. Huggins' discovery that the great Orion nebula is gaseous, it was not difficult to see that the Argo nebula must also be so. At any rate, this has been established by Captain Herschel's spectroscopic researches. The other prediction was more venturesome. Sir John Herschel, whose opinion on such points one would always prefer to share, had expressed his belief that the nebula lies far out in space beyond the stars seen in the same field of view. I ventured to express the opinion that those stars are involved in the nebula. Lately there came news from Australia that Mr. The substance of a Lecture delivered by R. A. PROCTOR, B.A., at the Royal Institution on May 6. Eight pictures of nebulae were exhibited in illustration of this peculiarity. bourne, has found that the nebula has changed in which minute satellites must be as the sands largely in shape since Sir John Herschel observed on the sea-shore for multitude; the wonderful it. Mr. Le Sueur accordingly expressed his belief zone of asteroids; myriads on myriads of comets; that the nebula lies nearer to us than the fixed millions on millions of meteor systems, gathering start seen in the source feld of view. More lately, however, he has found that the star Eta Argus is shining with the light of burning hydrogen, and he expresses his belief that the star has consumed the nebulous matter near it. Without agreeing with this view, I recognise in it a proof that Mr. Le Sueur now considers the nebula to be really associated with the stars around it. My belief is that as the star recovers its brilliancy, observation will show that the nebula in its immediate neighbourhood becomes brighter (not fainter through being consumed as fuel). Infact, I am disposed to regard the variations of the nebula as systematic, and due to orbital motions among its various portions around neighbouring stars. As indicative of other laws of association bear ing on the relations I have been dealing with, I may mention the circumstance that red stars and variable stars affect the neighbourhood of the Milky Way or of well-marked star-streams. The constellation Orion is singularly rich in objects of this class. It is here that the strange "variable" Betelgeux lies. At present this star shows no sign of variation, but a few years ago it exhibited remarkable changes. One is invited to believe that the star may have been carried by its proper motion into regions where there is a more uniform distribution of the material whence this orb recruits its fires. It may be that in the consideration of such causes of variation affecting our sun in long past ages a more satisfactory explanation than any yet obtained may be found of the problem geologists find so perplexing the former existence of a tropical climate in places within the temperate zone, or even near the Arctic regions.* more and more richly around the sun, until in his neighbourhood they form the crown of glory which bursts into view when he is totally eclipsed. But wonderful as is the variety seen within the planetary system, the variety within the sidereal system is infinitely more,amazing. Besides the single suns, there are groups and systems and streams of primary suns; there are whole galaxies of minor orbs; there are clustering stellar aggregations, showing every variety of richness, of figure, and of distribution; there are all the various forms of nebula, resolvable and irresolvable, circular, elliptical, and spiral; and lastly, there are irregular masses of luminous gas, clinging in fantastic convolutions around stars and star-systems. Nor is it unsafe to assert that other forms and varieties of structure will yet be discovered, or that hundreds more exist which we may never hope to recognise. But lastly, even more wonderful than the infinite variety of the sidereal system, is its amazing vitality. Instead of millions of inert masses, we see the whole heavens instinct with energy, astir with busy life. The great masses of luminous vapour, though occupying countless millions of cubic miles of space, are moved by unknown forces like clouds before the summer breeze; star-mist is condensing into clusters; star-clusters are forming into suus; streams and clusters of minor orbs are swayed by unknown attractive energies; and primary suns singly or in systems are pursuing their stately path through space, rejoicing as giants to run their course, extending on all sides the mighty arm of their attraction, gathering from ever new regions of space supplies of motive energy, to be transformed into the various forms of force,-light, and heat, and electricity, and distributed in lavish abundance to the worlds which circle round them. Truly may I say, in conclusion, that whether we regard its vast extent, or its infinite variety, or the amazing vitality which pervades its every portion, the sidereal system is of all the subjects stupendous. It is as a book full of mighty problems, man can study, the most imposing and the most of problems which are as yet almost untouched by man, of problems which it might seem hopeless for him to attempt to solve. But those problems are given to him for solution, and he will solve them, whenever he dares attempt to decipher aright the records of that wondrous volume. SCIENCE FOR THE YOUNG.* (Continued from page 223.) § II.-FLEXIBILITY. LEXIBILITY is the capability of bending permanent of par It remains that I should exhibit the general results to which I have been led. It has seemed to many that my views tend largely to diminish our estimate of the extent of the sidereal system. The exact reverse is the case. According to accepted views there lie within the range of our most powerful telescopes, millions of millions of suns. According to mine, the primary suns within the range of our telescopes must be counted by tens of thousands, or by hundreds of thousands at the outside. What does this diminution of numbers imply but that the space separating sun from sun is enormously greater than accepted theories would permit? And this increase implies an enormous increase in the estimate we are to form of the vital energies of individual suns. For the vitality of a sun, if one may be permitted the expression, is measured not merely by the BY THE REV. E. KERNAN, CLONGOWES COLLEGE. amount of matter over which it exercises control, but by the extent of space within which that matter is distributed. Take an orb a thousand times vaster than our sun, and spread over its surface an amount of matter exceeding a thonsandfold the combined mass of all the planets of the solar system:-So far as living force is concerned, the result is-nil. But distribute that matter throughout a vast space all round the orb -that orb becomes at once fit to be the centre of a host of dependent worlds. Again, according to accepted theories, when the astronomer has succeeded in resolving the milky light of a portion of the galaxy into stars, he has in that direction, at any rate, reached the limits of the sidereal system. According to my views, what he has really done has been but to analyse a definite aggregation of stars-a mere corner of the great system. Yet once more. According to accepted views, thousands and thousands of galaxies, external to the sidereal system, can be seen with powerful telescopes. If I am right, the external star-systems lie far beyond the reach of the most powerful telescope man has yet been able to construct, insomuch that perchance the nearest of the outlying galaxies may lie a million times beyond the range even of the mighty mirror of the great Rosse telescope. But this is little. Wonderful as is the extent of the sidereal system as thus viewed, even more wonderful is its infinite variety. We know how largely modern discoveries have increased our estimate of the complexity of the planetary system. Where the ancients recognised but a few planets, we now see, besides the planets, the Sir John Herschel long since pointed to the variation of our sun as a possible cause of such changes of terres trial climate. ticles in a body. This is an important property, in consequence of practical questions which it involves. No. I.-Laws.-A body in which the dimension of length is considerably greater than the other two dimensions, may be viewed as constituted by three sets of particles-the upper, the lower, and the middle. The conditions of these in a flexed body are the subject of the few but important laws of flexibility. A rod with wires passed through it, shows well, in an enlarged form, the When the wires carry meaning of the laws. white beads the action is made still more evident, Fig. 37. Lead or some body that keeps the bent form, is the best material for the rod. Law I. The upper particles of a flexed body are separated without destroying their molecular attraction. Hold the wired rod, the wires perpendicular, bend the ends down, the wires diverge, forming an angle between each pair. The beads, as Fig. 38, represent the particles as separated by the action of bending. N.B.-The terms upper and under, are not to be taken in their ordinary sense only. For then the laws would refer to but one sort of flexion centre raised up, ends bent down. Every flexed body has a convex and concave side. And in this sense are used the terms upper and under. Law II. The lower particles of a flexed body are compressed. Look at the beads below (a), they are close up, or perhaps overlapped. *The copyright of this series of articles is reserved by the Author. |