the two brasses and the plate spans, the brasses passing up the groove, being held in position by a serew at E. The opening for the brass (in the rodend) is here shown wide enough for the rod-end to pass over the collar of the crank-pin, but in many cases, with this as well as with other forms of solidended rods, the crank-pin may be made plain, that is without a flange, and have a washer secured by a screw (as shown in Figs. 11, 12, and 13), so that by removing the washer the rod may be put on with the brasses already in place, and made no thicker (at the joint face) than is necessary for strength. In fig. 15 is shown what may be termed a clip-end SCIENTIFIC NEWS. to the material employed in the light. A cylin der of platinium foil around a rod of lime gives an excellent light, and strips, wires, rods, beads, HE specification of a patent obtained in and pieces of iridium, ruthenium, rhodium, osTHE Edison has been published mind, metals that fuse, at by one of the daily papers with all the reference high temperature, may be used. Also conducting marks to the 51 figures, but without the figures oxides may be used, such as oxide of titanium themselves. The readers of the Standard are ex- and even silicon and borax are mentioned. Mr. pected to supply them out of their own heads. Edison claims the points above noted, the thermal Mr. Edison says:-"It has long been known circuit regulator in several forms, and also claims that if two electro-magnets, or an electro-magnet the combination with an electric light of a diaand a permanent magnet be drawn apart or phragm operated by the expansion of a gas or fluid in proportion to the temperature of the light to regulate the electric light. The combination of a vibrating body with mechanism, to maintain its vibrations, as a means of converting a "small mechanical force" into a "powerful electric current" is also claimed. B 4 A 5 12 B 15 B 13 NOTES ON NOVELTIES. Illustrated Guide for Amateur Gardeners. 9 According to the Athenæum the experiment of illuminating the reading-room of the British Museum by the electric light has proved, "so far as is yet ascertained," perfectly successful. The words quoted read strangely, and seem to cast some doubt upon the statement, or upon the writer's knowledge. The death of Mr. Bennet Woodcroft, F.R.S., formerly clerk to the Commissioners of Patents, is announced as having occurred on the 7th inst. The deceased gentleman, who was in his 76th year, was well-known in connection with the carrying out of the Patent Law Amendment Act of 1852, in which year he was appointed to the office which he held until his retirement in 1876. He was himself an inventor of several contriv ances of considerable merit, and "Woodcroft's tappets" are largely used in the looms employed for weaving certain descriptions of fabrics. On the history of inventors and inventions he was a well-known authority, besides being a diligent collector of potraits of inventors and discoverers. His best known work is a valuable sketch of the History of Steam Navigation," and he issued also a curious reprint of the famous "Treatise of Hero of Alexandria on the Early Engines," which all collectors of scientific books have long highly prized. Mr. Proctor lectured at the Royal Institution, last week, on the "Great Pyramid of Ghizeh." He put forward the theory that astrology was the moving cause for the erection of the pyramids, which had obviously been erected for astronomical purposes. If built merely as tombs, why were there so many? The reason is that each king must have his own, because, although used as tombs, they were employed for watching the stars, and learning the times when the interests of the king could be best advanced; hence, the observations must be carried on independently. The chambers in the interior were no doubt intended to serve as observatories; and the pyramid was probably constructed in layers, one for each year of the king's reign. connecting-rod, the screw closing the rod-end (to | caused to pass by each other, electric currents take up the wear) against the spring of the metal. will be set up in the helix of the electro-magnet. It is obvious that in this case the hole may receive a It has also been known that vibrating bodies, Mr. E. A. Cowper has invented a telegraph brass bush split as is the rod-end and secured from such as a tuning-fork or a reed, can be kept in writing machine, by which the exact strokes of turning by a pin. Fig. 16 presents another form of vibration by the exercise of but little power. I a pen can be reproduced at a distant station solid end-rod, which admits of the use of a brass having a flange on both sides of the strap, and will avail of these two known forces [sic] and com- The apparatus is about to be exhibited at the take on and off by removing the cap, B. If the bine them in such a manner as to obtain a power- Society of Telegraph Engineers, and if it is not crank-pin collar is solid, the brasses must be placed ful electric current by the expenditure of a small liable to get out of order on the slightest occa on the crank-pin, and the rod, with the wedge in mechanical force. Then follows a description of sion, it will undoubtedly be in great demand. place, lifted or lowered to the brasses; but if the this novel magneto-electric machine, which has Mr. J. W. Swan gave an interesting lecture on crank-pin has a washer and screw, the rod may be tuning-forks two metres or more in length, carry-the "Electric Light," at the Literary and put together and slipped on its place. ing permanent or electro-magnets upon each Philosophical Institute, Newcastle-upon-Tyne, prong, which are opposed to the cores of electro- last week, Sir W. Armstrong being in the magnets suitably situated, the alternate current chair. Mr. Swan thought the problem of an produced being available for the electric light. A economical electric lamp would ultimately be small "air, gas, or water engine is applied to solved. each end of the fork. A correspondent forwards Edison prefers, but he describes several modifi- under the presidency of Mr. C. Hunt, who, in the The annual general meeting of the Midland us a drawing of the current regulator which Mr. Association of Gas Managers was held last week, cations in his specification, in which many mate- course of his address, spoke of the electric light, rials are mentioned as light-giving substances." and pointed out its great defect to a practised Mr. Edison says it is preferable to have the light eye-its lack of the power of diffusion. Mr. within a case or globe, and that various things Hunt thinks that whatever has been achieved by may be employed "to lessen radiation, return electricity in the improved lighting of our streets the heat, and lessen the electric energy required "e.g., alum water between concentric can be done better and more cheaply by coal-gas. cylinders, or coloured or opalescent glass, or solu- Mr. H. T. Wood, Assistant-Secretary to the Fletcher's Apparatus.-We have also received tion of sulphate of quinine. A variety of Society of Arts, having informed the Science and the catalogue of blowpipe, &c., apparatus made by helices, coils, ribbons, and other forms of light-Art Department, South Kensington, that suffi Mr. Fletcher, of Warrington, concerning which we giving materials are illustrated, and Mr. cient funds will be provided by the City comcan only say that if not known to every metallurgist Edison remarks that in all cases the light is due panies for the payment of teachers of classes for and chemist in the kingdom, it should be. Mr. to the incandescence of the body, and instruction in technology, on the same scale as Fletcher has provided workers in laboratories with that the thermal regulator of the circuit that on which teachers of science classes are now appliances unknown to their ancestors, and the is to be adjusted or made to act automatically paid by the Science and Art Department, with many useful apparatus proceeding from his factory circular has been issued need no commendation at our hands, for they are to lessen the electric current before the same out reduction, a known and appreciated in every laboratory in this becomes sufficiently intense to injure the light- requesting that information of the formation of giving substance. This point will vary according any classes in technology, with the number of country. -We have received from Messrs. Daniels, of Norwich, which we find keeps up its character as one of the best of the gardening catalogues. We have previously spoken in favourable terms of this work, and can recommend it to amateurs who want to know what seed to sow and how to grow the plants. The "Guide" is, in fact, a multum in parvo, and a gardener's library is incomplete without the current their illustrated "Guide for Amateur Gardeners,' issue. The committee inquiring into the explosion on board the Thunderer have reported that the gun, having missed fire when loaded with the battering charge, was again loaded with a full charge, and fired with both of the charges and the projectiles in the gun at the same time." the gun had been a breechloader, would the second charge have been loaded in ignorance that the first was still in the gun? If her pupils attending them, and the probable number Professor Cohn, who has lately given this atten- The Queen has approved the appointment of that will come up for examination in May next, tion, comes to a different view; he regards the Mr. Warington W. Smyth, F.R.S., Sir George may be furnished to the Science and Art depart-matter of these threads as an excretion pressed Elliot, M.P., Mr. F.A. Abel, C.B., Mr. Thomas ment as soon as possible. out through openings of the cuticle, and their Burt, M.P., Mr. Robert Bellamy Clifton, F.R.S., movements as phenomena of soaking and swell- Professor Tyndall, F.R.S., Mr. Lindsay Wood, ing. Another interesting point relates to the and Mr. William Thomas Lewis," as protective use of the beaker surrounding the Majesty's Commissioners for the purpose of stem. According to Kerner, the matter collect- inquiring and reporting whether, with respect to ing in this cistern keeps off undesirable guests, the influence of fluctuations of atmospheric which might creep to the flowers, and take away pressure upon the issue of fire-damp from coal, the nectar, without helping fertilisation. Now, to the adoption and efficient application of trustProfessor Cohn observed on specimens of worthy indicators of the presence of fire-damp, dipsacus, at Breslau, that the water gave and generally to systematic observation of the very imperfect protection of this kind, for the air in mines, to improved methods of ventilation flower-stems above the leaves were, notwith- and illumination, to the employment of explosive standing both thorns and the water obstacle, agents in the getting of minerals, and to other covered with plant lice. particulars relating to mines and mining operations, the resources of science furnish any practicable expedients that are not now in use and are calculated to prevent the occurrence of accidents or limit their disastrous consequences. According to the German sanitary authorities, the disease epidemic in Astrachan is identical with the black death, or the "plague of London.' The outbreak has been very intense, but is limited in area, and the disease has appeared in the midst of a population who had done everything to afford it full scope for the exercise of its virulence. M. Cappanera, having translated Culley's "Manual of Practical Telegraphy" into Italian, is now at work on Mr. Sprague's "Electricity." We hear that the 13-in. silvered glass reflector on Berthon's equatorial stand exhibited in the Paris Exhibition by Horne and Thornthwaite, and for which that firm obtained a silver medal, has been purchased by Professor Janssen for the Meudon Observatory, near Paris. A phenomenon witnessed in some parts of France on the 22nd and 23rd January, has been a subject of comment in the French Academy. Professor Masse, of Epernay, reports that all objects exposed to a rain which then fell became suddenly covered with ice, and he thinks this was a case of congelation of water in a state of surfusion. The water was not frozen, as is often the case by fall on bodies whose temperature was below zero, for the effect was observed on objects comparatively warm, such as umbrellas, and even the figures of passengers. On the other hand, Professor Decharme, of Angers, reports the formation (at the dates just specified) of a layer of transparent ice, through freezing of water under the action of a sharp east wind. Leaves of green trees were rounded by a layer of ice fifty times their weight. Many trees were broken in some parts under their unwonted burden. The phenomenon caused serious accidents, and interrupted several services. The ice-covered telegraph wires acted with difficulty. port. sur Experimenting on the mixed gases, Herr Sir. F. Leighton, the President of the Royal Academy, and Mr. Charles Manby, the Secretary of the Institution of Civil Engineers, were on Monday presented with the freedom of the Turners' Company. Sir F. Leighton, in the course of his reply, said the Turners' Company presented an example deserving of imitation of the amount of good which may be achieved with exceptionally slender means. in a recent number of the Annalen der Physique, should be represented in the Presidency of the Metallic chromium has only been obtained Here we have a new Probably the first private dwelling-house ever lighted by electricity was that of Professor Farmer, of the U.S. torpedo station, at New-manganese can be obtained in the same way, and the author has remarked that when the His parlour was lighted thus every distillation of the mercury takes place at a evening in July, 1859, (i.e., 19 years ago,) and temperature near 350 deg., the manganese obthe electric light was subdivided, too. The tained is pyrophoric. current was supplied from a battery of 2 dozen resemblance between manganese and iron. 6-gallon jars in the cellars, to two electric lamps in the parlour, one at each end of the mantelpiece. One, or both, could be lighted at once by simply turning a little button. The light was much liked, but its use was discontinued simply because it cost about four times as much as an equivalent amount of gas-light. With the cheaper electricity from the dynamo-electric machine, he looks for better things in this direction. From experiments recently made by Mr. Auston, of Coatsville, it would seem as though a piece of iron might be loaded just beyond its socalled elastic limit, and preserve its ductility or toughness so as to yield with every small increase of load; but if you load a piece to very nearly its so-called elastic limit, and keep it there, it will become rigid, and not elongate without a very decided increase of load. A very sensitive telephone, devised by M. Gower, giving the voice and other sounds distinctly enough to be heard throughout a hall, though transmitted through a great wire resistance, was presented to the French Academy the other day. The magnet used is a horse-shoe one; the plate is large and thick, the inclosing case is metallic, and a speaking tube is fitted to the instrument. received from our New York correspondent, Mr. The Journal des Usines à Gaz says:-"We have Warren Dresser, a letter from which we extract the following: Edison has as yet accomplished nothing; he has a lamp, but one which will not work until he has found a new machine to generate electricity. The report runs that he has spent 76,000 dols. (£15,800) in experiments, and that his friends now refuse to furnish him with fresh funds. They find that for a long time he has shown them nothing for their money. I believe that the panic is past, and that there is some hope of seeing better times, and I am certain that gas shares will continually increase in value.' When we remember the excitement caused by the news of Edison's pretended discovery and the sensational articles published by the leading papers, and see the nullity of the results obtained, we think of the fable of the mountain which brought forth a mouse, and we ask whether good faith has always been the rule of newspaper correspondents." USEFUL AND SCIENTIFIC NOTES. The Age of Sedimentary Rocks.-Mr. J. Mellard Reade has made a communication to the Royal Society on 66 Limestones as an Index of Geological Time." He believed that analogy leads us to regard the earliest materials as of the nature of granite and basalt. He calculated the average sedimentary thickness at one mile, and that onetenth of the thickness of this is calcareous. The later strata of England are much more calcareous than the earlier, and this holds good for Europe. This was regarded as indicating an increase in lime available in the formation of sedimentary deposits, and it was pointed out that the annual depth of rain running off the granite and igneous rock areas is averaged at 28 inches, and the annual contribution of lime in the forms of carbonates and sulphates is 70 tons per square mile. From this Mr. Reade has calculated that the elimination of calcareous matter contained in the sedimentary crust of the earth must have occupied at least 600 millions of years. An eccentric man accomplished a journey last year from New York to San Francisco, drawing a wheelbarrow. The wager was about £200. The man is about 40 years of age, firmly built, and slightly under average stature. He left New York on the 20th of June, and reached the Pacific Coast on the 16th of October, having passed through the greatest dangers especially in the Prairie and the Rocky Mountains, where he narrowly escaped being scalped by the A mirror barometer of singular construction, Indians. He passed through Montgomery and great sensibility, has been invented by M. street in San Francisco (where a crowd had Teisserenc de Bort. It is deseribed in a recent turned out to see him), stolidly wheeling his number of La Nature. The instrument is one barrow, and preceded by a Mexican in native of the aneroid class, and is especially well costume. The barrow, made expressly for this suited for precise observations at sea in rough in the metropolis is unfortunately assuming exThe Strike. The strike in the engineering trade extraordinary journey is very light, and is weather, where it is impossible to read the tended proportions. The works of Messrs. Penn fitted with a box for provisions. It bears the mercury barometer. The mirror is pivoted in inscription, "En route from New York to San about a vertical plane on a horizontal axis above the elastic case, and derives motion from the It has been observed by Mr. Francis Darwin latter through simple contact of a small palet that out of the glands of the beaker-shaped on the axis with a metallic point on the case. leaves of Dipsacus there come threads, which Through a telescope fixed horizontally, you view perform peculiar amoeboid movements in the in the mirror the reflection of a vertical scale. water which collects in the leaves. He con- This barometer has had little use as yet, but cluded these were threads of protoplasm, which in recent observations by M. Perrier, in a captive absorbed nitrogenous substances from water. I balloon, it gave very satisfactory results. Francisco." and Sons, of Greenwich, were on Monday affected for the first time. Both there and at the shops of Messrs. Humphreys and Tennant, of Deptford, which rank next in degree to those of Messrs. Peun, information at the time of our going to press fixes the turn-out may be said to be general. The latest the approximate number of men out on strike at about fifteen hundred, while the total number of men employed in the London engineering trade not in any way affected by the reduction is estimated at from eight to nine thousand. LETTERS TO THE EDITOR. W.O. [We do not hold ourselves responsible for the opinions of our correspondents. The Editor respectfully requests that all communications should be drawn up as briefly as possible.] All communications should be addressed to the EDITOR of the ENGLISH MECHANIC, 31, Tavistock-street, Covent-garden, All Cheques and Post-office Orders to be made Payable to In order to facilitate reference, Correspondents, when mentioning the number of the Letter, as well as the page on which it appears. J. PASSMORE EDWARDS. speaking of any Letter previously inserted, will oblige by "I would have everyone 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 from whence great inconveniences derive their original." Montaigne's Essays. to tell him that his hypothesis as to the misspelling the key plan of Captain Noble's drawing of Nov. 2, THE ASSUMED TEMPERATURE OF NOMICAL EDUCATION-TIME-SUN- sketch. [15387.]-Ir is much to be regretted that people like "J.H.E" (letter 15351, p. 517), will persist in rushing into print, without the most rudimentary knowledge of the subjects on which they profess to instruct others. In limine, your correspondent is utterly wrong in his assertion that "Hitherto, at all events, the laws of decrease of radiant heat has been alone interrogated so as to form an idea, or rather settled assumption, by science as to the temperature of each of the primary planets." Had he read, for example, the works of Mr. Proctor, he would have found an array of facts tending to show that almost certainly the larger planets Jupiter, Saturn, Uranus, and Neptune are still red-hot, and act in some sort as suns to the satellites which surround them. In the next place, his statement that the Sun "is of such vast magnitude that two millions of miles would not be too great an estimate of its diameter," can only be explained, though scarcely justified, by the inclusion of the Corona (and perhaps the Zodiacal light as well) in that diameter! Thirdly, the amount of heat received by any given body from the Sun is constant as long as its distance remains constant; and its radiation of heat into space would proceed cæteris paribus just as quickly if it were at rest as though it were in motion. The very analogy which "J. H. E." attempts to establish between the radiation of a planet into void space, and the abstraction of heat from the human body consequent on its rapid passage through air, suffices to show that he has not grasped the very rudiments of the knowledge necessary to enable him to theorise. I cannot profess to teach the writer of such a letter as 15351 the elements of Astronomy in these columns; but, without further reference to other parts of that letter, I would merely observe in connection with its final paragraph that the Earth does receive 1-15th more heat and light during its perihelion passage than it does at the time of its aphelion; and that but for its rapid motion through perihelion (and consequent inequality in the length of the seasons) the Southern Hemisphere would actually receive more heat per annum than the Northern one. "J. H. E." will find this perspicuously explained on pp. 231 and 232 of the last edition of Sir John Herschel's "Outlines of Astronomy.", Letter 15352 (p. 518) has sent me back to its precursor, 15252 in p. 419. Merely remarking that Mr. D. must have secured an "artist's proof" of his engraving, I would ask, in all humility, which is the fine hairline? Is it north or south of the ring or where? It is indeed A Welcome Contradiction" that comes from Mr. Herbert Sadler in letter 15360 (p. 519). It certainly did appear to me in the last degree doubtful that men of the intellectual and scientific eminence of the office holders of the Selenographical Society should have yielded to any extraneous influence in the direction to which the rumour in your "Scientific News" pointed; and I am sincerely gratified to find that my scepticism was so well justified. "Telescope Tele" (query 35525, p. 526) could not be criminally proceeded against if his dog killed a fowl under the circumstances specified unless it had previously shown a tendency to avicide; but, of course, an action would lie against him in the County Court for the value of the deceased bird. In thanking "A. E. S." (letter 15371, p. 540) for and attempt to enlighten me, I am compelled And in answer to his succeeding query (35619, "A. C. F." puts rather a vague query (35664) on two on each side. It appears from the accounts which have reached me that on the evening of Nov. 2, Mr. Baxendall blackness had become very decided. This was the observed the crater at 6h. 15m., and by 6h. 45m. the time at which Mr. Capron dated his sketch and described the spot as nebulous, also his not being able to focus it. Captain Noble's drawing is dated from 8h. to 9h. Mr. Baxendell observed a change between 6h. 15m. and 6h. 45m., blackness increas Sunshine will answer the purpose of "Mac" (querying. A Fellow of the Royal Astronomical Society. 6h. 45m. and Sh., by which in some way it was renHad another change supervened between dered invisible? With regard to the nebulosity of the object, two instances are familiar to me, the cloud-like appearance of the white patch west of Picard, and the interior of Tycho. Most observers are acquainted with the first, as to the interior of Tycho, it is now many years since I had a great difficulty in focussing it. It appeared always misty and ill-defined. At length this mistiness disappeared, and the interior became perfectly distinct and sharply defined, when I saw very plainly the smaller hill on the north-western side of the large central hill, mentioned by Webb in "Celestial Objects," third edition, p. 104. In comparing Capron's statement with these instances there appears to be great reason that a most careful watch should be kept on Klein's object, especially as it has presented parallel phenomena to the two instances abovementioned.. REGION NEAR HYGINUS. [15388.]-IF Mr. Dennett had taken the trouble to have consulted the article with the above heading in the ENGLISH MECHANIC, Dec. 13, 1878, No. 716, P. 335, when he had observed the dark spot mentioned in Letters 15326 and 15352 he might have saved himself the further trouble of perusing the The Astronomical Register, February, 1879, two paragraphs relating to it, for a dark spot in its p. 36, reports the following words of Mr. Nelson, locality has been registered for some years as I have not seen it, and to this day I have not seen IA ŋ 4. The statement in Letter 15326 "and it," speaking of Klein's object. We may regard likewise the S side of the western arm of the clefts this as evidence that Mr. Neison has really not seen for some distance on Jan. 9d. 11h.," indicates that the object. His conclusion, therefore, that it is the extension of the darker tint westwards is a new new is based not upon his own observation, but feature, for in most drawings which I possess the upon the published and written accounts of those spot has a circular form. I should have thought who state they have seen it. All the confusion that that with Mr. Dennett's increasing knowledge of has arisen may be cleared away, and we may arrive selenography he would have consulted the article at approximate certainty if for the future observers in the ENGLISH MECHANIC, Dec. 13, 1878, and will conscientiously align the object (supposed to pointed out the different forms under which Captain be Klein's crater) in the way above-mentioned, Noble and he saw it and endeavoured to obtain con- giving the designation of the conspicuous objects firmation of his own observation before he ventured employed as they occur in existing maps. to amend "Lunar Chart No. 1." The spot in ques- In the report of the meeting of the R.A.S., pub tion, as represented by Captain Noble, appears as lished in the Observatory for February, 15, at least three times the area of Hyginus, with ill-p. 328, Mr. Neison is reported to have said, "the defined edges and a darker tint S. and S.E. of the cleft, which, however, is not so dark as the spot itself. It is to be regretted that Mr. Dennett has not furnished the readers of the ENGLISH MECHANIC with a drawing of the extension of the darker tint, showing the alignments of its S.W. and N.E. extremities; but as they possess in No. 716, p. 335, reason why Mr. Pratt and Lord Lindsay did not ses the crater on the 17th Oct., must have been that it was then within the shadow of the lofty ridge on the east." I am uncertain as to the precise locality which Mr. Neison assigns to the new crater, but from his statement that" on Oct. 17 it was within the shadow of the lofty ridge on the east"-i the western portion of the outer circumvallation of TEMPERATURE OF PLANETS - THE All these experiments were made on iodised silver plates. Shortly afterwards the experiments were confirmed in this country by Herschel, Powel, and others, who devised more than one way of proving "the existence" of invisible rays of low refrangibility other than "by their thermal effects." distance at which I can read this print is 6 inches. should be indicated. Stockton-on-Tees, Feb. 6th. C. W. Hodgson. PHOTOGRAPHY AT THE RED END OF .. THE SPECTRUM. The Ghost of Daguerre. AUTOMATIC COUPLINGS ON RAILWAYS. despatch of traffic by the use of automatic coupling, ject in your issue of 31st ult. You admit the great importance of the saving of time secured in better and yet a few lines further on you consider the advantages I show as visionary, because the eight minutes you suggest as a time-saving per train would probably have no effect on the actual time for departure of a particular train. [15389.]-THE first consideration which, as it appears to me, might have suggested itself to J. H. E." before writing letter 15351, p. 517, to "remind our philosophers" that the usual law of [15390.]-FROM Captain Abney's article, pub[15391.]-I DESIRE to say a word or two on your decrease of radiant heat is not applicable to the lished in the Times of Dec. 28, "On Recent Ad-article upon the contents of my lecture on this subtemperatures of bodies in motion is, that it would vances in the Applications and Science of Photocircumstance, if true, escaped the attention of the years no photographic effect had been obtained from be little less than miraculous had so elementary a graphy," one would gather that until the last few many great men who have made such matters the the rays at the red end of the spectrum. After restudy of their lives. His error lies in confusing ferring to the experiments of Dr. Vogel, of Berlin, conduction with radiation. He instances "persons and to Captain Waterhouse, the article proceeds: riding on an open vehicle in still and cold air feel Following in their steps, Captain Abney has colder when it is running than during a stoppage." shown that not only all the visible radiations can Though not one of the "experienced correspond- make an impression on a simple silver compound, whose opinion he asks about the applicability but that the dark rays of low refrangibility, the of this illustration to the earth's motion, I may existence of which was previously known solely by perhaps be allowed to say that my opinion is that their thermal effects, can be similarly effective when space is not occupied with a medium like our the simple compound is so prepared as to absorb atmosphere, which indirectly accelerates these radiations. Here we have a possibility of radiation () of internal heat, through the layer extending our knowledge of spectrum analysis and of air enveloping the earth being with its heat (or solving problems which heretofore were impossible radiation) left behind and renewed at intervals." to grasp." Radiation is not the heat which a layer of air in contact with a warm body possesses, and diffuses very slowly indeed, but, on the contrary, a mode of heat which flies away, if I may speak so, at the rate of ents 185,000 miles a second. It is true in one sense that the mean temperature of the earth is considerably greater in June than in December, when the sun is three million miles nearer to it; but it is also true that in the latter case the earth receives about one-fifteenth more heat. The explanation of this is to be found in the great predominance of land in the northern hemisphere. I trust "J.H.E." will further cultivate the subject," and will be more fortunate the next time. "A.E. S.," on p. 519, enters a just protest against the two frequent use and misuse of foreign phrases in our language. Any writer should see that a profuse sprinkling of such phrases will only give a pedantic appearance to his productions. I cannot see much advantage in mixing languages-hope there will never be a common language, and dislike to come across English phrases when reading French or German. However, there are a great many French words which are so constantly used that they have become as well known as English to a moderate reader, and there are some which express ideas for which we have no apt English words. Moreover, French and Latin suit some people's style of writing more than others. Such words as beau monde, chaperon, tapis, being unknown in the French language in their English seuses, may be described as slang. That defective vision is a subject of considerable interest among your readers, the queries which relate to it abundantly testify. And though they may not be so frequent on short sight as on other defects, yet this subject must be at least interesting, to as many readers as the eternal discussion on Nos. of engines and speeds of trains. The other day, I came upon the article on Defects of Sight in Chambers's Encyclopædia. Remarking on myopia, the writer says "So far from shortsightedness improving in advanced life, as is popularly believed, it is too frequently a progressive affection." This agrees with my own limited observation, and not long ago some statistics were given in your "Scientific News," of the increase with age in the percentage of short-sight in schools in Germany. As popular sayings of this kind, however, are rarely without foundation, and as the cornea of ordinary eyes becomes less convex with increasing age, I should like to hear the opinions of some of your competent readers, upon the generality of the rule that short-sight does not improve with age. That this affection is brought on, or, where congenital, increased, by excessive reading seems placed beyond doubt. The article alluded to in Chambers' Encyclopædia, quoting from Donders, says "While in the Foot-guards, consisting of nearly 10,000 men, not half a dozen men have been discharged, nor half a dozen recruits been rejected on account of this imperfection, in a space of 20 years, in one college at Oxford no less than 32 short-sighted men were met with out of 127.'" I, myself, have been an omnivorous reader from youth, and the greatest I expected that Dr. Draper, or some other of the scientific photographers of my generation who are still alive, would have written to correct this mistake; but, as now more than a month has elapsed without any correction, and as I see that some of Captain Abney's friends are referring to him as the talented discoverer of photography at the red end of the spectrum, I think it time to send you some references to the early history of the photography of the less refrangible rays. In the Philosophical Magazine for November, 1842, Dr. John William Draper (the elder) published an account of some photographs of the spectrum which he had obtained, showing lines considerably below A of Fraunhofer's spectrum. These lines he named a, B, and y; he also succeeded in photographing every part of the spectrum, from the extreme ultra-violet above P down to the ultra-red below Y. In his recently-published volume of scientific memoirs, pp. 87-89, Dr. Draper refers to still earlier physicists who had detected chemical action at the red end of the spectrum. He writes:-"That the opposite ends of the solar spectrum possess opposite qualities, is an idea which has been floating among chemists for many years. The first distinct statement in relation to it with which I am acquainted occurs in a work published by Mr. B. Wilson, the second edition of which dates as early as 1776. It is entitled "A Series of Experiments on Phosphori." He shows that it is the more refrangible rays which excite the phosphorescence of sulphide of lime, but the less refrangible ones extinguish it when shining. "In 1801 Ritter found that chloride of silver which had been blackened in the violet rays, had its colour partially restored when placed in the red. He states also that phosphorus, which is oxidised with the production of fumes in the invisible red, is instantly extinguished in the violet. "The well-known experiments of Wollaston with guaiacum served to show the opposite relations of the red and violet rays. It is remarkable that he subsequently abandoned this interpretation of the phenomena on discovering that green guaiacum changed its colour by the application of a hot silver spoon. "In 1839 Sir J. Herschel encountered the same action in the case of some of the preparations of silver. His first idea was that of a positive and negative polarity of the spectrum; but this was subsequently modified for the reasons set forth in his memoir (Phil. Trans., 1840, § 60, etc.)" Shortly after 1842 M. Becquerel, without having heard of the research of Dr. Draper, succeeded in obtaining traces of the spectrum below the visible limits, but it appears that he did not obtain the lines a, B, Y. In 1846 MM. Foucault and Fizeau deposited with the secretary of the French Academy a sealed It is well-known that the trip system has been introduced chiefly on account of the large proportion of goods trains which exceed their time table journeys by some 50 per cent. of time, and it is designed to meet by an average payment the extra cost of working on particular trains where the working expenditure per journey extinguishes the profit. to It is the knowledge that these journeys can be expedited by automatic couplings and the average expenditure per train reduced that leads me enforce this proposition with all the earnestness I can, and I will do my best within reasonable limits to show you how this can be. Twenty trains per day from a station where the saving of time per train reaches six minutes, yields two hours. But you contend that in spite of being ready earlier they start no sooner. How many goods trains leave their first station to time, much less the second station? Very few, as far as I can learn. An earlier start by six minutes to the first train may do no more than get it away to timetable time, but it gives the following train twelve minutes in which to get made up and be despatched, and so throughout the day at that goods yard punctuality is advanced and the engine free to execute other shunting in the yard or for other duty if needed. The value of this at various centres must be great, but it is as nothing to what follows upon the despatch of the train. Numberless instances can be given in which the delay of a few minutes has closed the signals against a late train, and when shut back it gets later and later at station and siding; and I have in my recollection a train which I followed up which lost at the second station 15 minutes, never once got near its time-table time anywhere, and at its last point got shut out for 160 minutes-losing 5 hours in less than 100 miles. Such matters occur daily and hourly, as some of your correspondents on railway matters can confirm. Can it be doubted that the saving of time in the first case will vastly facilitate the getting through of the second, and that the third will have a better prospect, and those following advanced thereby. You also question reduction of collisions by automatic couplings. Collisions are certainly not directly the result of want of couplings, but undoubtedly many could be avoided by their use. It may be remembered that in the case of the Sittingbourne collision the goods guard in vain attempted to get the chain links on to the hook of the waggon to draw it out of the way, and hundreds of cases may be cited were facilities for prompt connection or disconnection, especially on the move, would prove invaluable. But yet another point. We are so accustomed to ascribe a collision to points, brakes, or faulty signalmen, that no one ever inquires how the wrecked goods train came to be where it was. Instances there are of collisions occurring when, according to time-table arrangements, the goods train should have been twenty miles away. As your writer suggests, automatic coupling savings depend on time saving, but the saving of money which must result therefrom constitute the strongest argument for the adoption of them. T. Attwood Brockelbank. Gresham House, Feb. 4, 1879. P.S.-Permit me to add that should your readers desire to study the subject, I shall be happy to post them, on application, a copy of my paper.-T.A. B. ་ [15394.]-PERMIT me to submit the following plan for "Carl's" approval or corrections. It taken from his design, Fig. 6, No. 35,218, January 10th. No. 720 of ENGLISH MECHANIC. I trust it will show I have paid some attention to his instructions, and it is possible it may be interesting to "Old Engineer," and others. [15392.]-I WOULD wish to have the opinion of some of ours" if the rise of the tide could be utilised for the above purpose, thus:-Have a large buoy or air vessel capable of floating or raising a "weight" of say 20 tons. Buoy to be made with flanges or rollers on sides to travel on guides, and "weight" similar, a chain from such " weight" and as tide raises buoy and weight, the slack of Numbers are in progressive order from 1 to 36. chain to be coiled on a cylinder in lighthouse, say I believe this pattern could be worked with 12 by a spring or balance-weight. Now, on fall of treadles in the hand loom. "Carl" will see I am tide, such weight to be utilised as an immense clock-of opinion that Threads Nos. 19, 25, 31, 39, 45, and weight, to actuate machinery to supply motive 51 are the same as Nos. 3, 9, 13, and Nos. 22, 28, power for an electric light, which would, of course, 34, 42, 48, 54, the same as Nos. 6, 10, 16. If this is be far superior to the oil lights used, and except so the pattern can be made on 10 shafts as above. first cost, after expense trifling. C A REFERENCES TO SKETCH.-A, air vessel as it would be at low water; B, weight as left by tide when full; C, guides or framing fastened to masonry: D, guide pulley for chain; E, winding-drum for chain and now source of power; F, balance-weight to take slack of chain; G, stays from guides to building; H, chain. If one tide per day would give sufficient power, buoy could be anchored down during rise of second tide, so as not to impede fall of weight. J. J. J. Old Overlooker. THE PERMANENCY OF CARBON PRINTS. [15395.]-HAVE any of your readers had much experience with carbon prints? I had always understood, and had perforce believed, that carbon prints were as permanent as anything could possibly be in this world; but I see from a recent meeting of the Berlin Photographic Society that there is at least a difference of opinion. Herr Reutlinger has, it appears, carried out a variety of experiments with a large number of samples of tissue, in which he carefully attended to all the precautions suggested by his own experience as well as by the instructions of others, so as to overcome all technical difficulties of the process. But in the durability of the prints thus obtained he has been bitterly disappointed. During the late exhibition he prepared some carbon prints with the greatest care on tissue obtained from the well-known house of Braun and Co., and exhibited them in the same case with a number of silver prints. After being thus exposed during the whole period of the exhibition-from six to eight months-the difference in the condition of the silver and carbon prints was most marked. The latter, when first exhibited, had a rich brown tone, but when they returned to the studio they had a dirty yellow tint shot with green, and had lost much of their original intensity; spots that had been retouched had become painfully manifest. During all this time the silver prints that had been exposed under exactly the same circumstances had remained unchanged. Herr Reutlinger believes the cause of the change of colour to be due to chemicals contained in the colouring material of the coating, or in the paper. His opinion is that the old silver process, if attention be paid to it, will long continue to bear the palm. Several subsequent speakers agreed with Herr Reutlinger, one in particular asserting that he had silver prints which were twenty-five years old, and as good as new in point of colour. Prof. Vogel explained that carbon pictures prepared on tissue tinted with Chinese ink or lamp-black would not fade. The cause of the change of colour experienced by Herr Reutlinger was to be found in the use of carmine, which is known to be an impure VIBRATIONS v. ELECTRIC LIGHT. and evanescent colour. Insufficient washing might [15393.]—THERE are two kinds of vibrations: one also, in consequence of a residuum of chromate, resolves into heat, as in chemical combustion; the produce a change of tint in carbon pictures. To other resolves into sound, as in the fractional vibra-obviate this, the treatment of the print with sodium tion of a musical string. As by means of heat vi- hyposulphite to decompose the chromate could be brations sound has been utilised and controlled, why recommended. He had twelve years ago prepared may not the converse be true that the sound vibrations his own tissue, and on the advice of the late Herr can control the heat vibrations? Thus: what would Grasshoff had used Vandyke red instead of be the effect if the circuit of an electric battery were carmine. Pictures taken on this tissue had not placed in vibratory motion, by means of a spring, or suffered the slightest change of colour in all that if part of the copper wire were tightened by means of time. tuning pegs, placed on a board with glass feet, and From a chemical point of view it would seem to vibrated by an insulated endless band or bow? I be a matter of course that pictures formed in an do not know what effect it would have on the elec-imperishable material like carbon would never tric are: it might produce a steadier continuous fade; but printer's ink does fade, and it may be light, or perhaps a more rapid combustion. Will that some unknown causes are at work in regard those who have the means put this theory into to carbon prints. practice and oblige a Fiddler? A Knight of the Camera. A SIMPLE ELECTRIC ALARUM. [15396.]-ALTHOUGH electric alarums are not strangers to your pages, I am not aware of having seen so simple an arrangement as that which I venture to introduce to your readers. All that is necessary to transform any common clock into an alarum in connection with an electric bell is, to connect one pole of the battery with the works of the clock (by attaching the wire to one of the screws connected therewith), and the wire from the other pole (having the bell attached) to a movable pointer, whose extremity is capable of different positions on the dial. The first point is easy enough. To accomplish the second: take a fat piece of mahogany or deal, the size of the top of your clock and about in. thick; into the side of this piece of wood, A, fix a binding screw, B. To the base of the binding screw (B) attach the wire from your bell, and fasten it to block A. The block may now be placed on the top of the clock and kept in position by an ornament, O. For the pointer bend a knitting-needle (or, better still, a piece of stout brass wire) into the shape represented by P (Fig. 3). Clamp this in the binding screw, B (shown in position). Now cut the minute hand of the clock, so as to make it shorter than the hour hand. If you wish to wake at six, clamp the pointer so that the point will be touched as the hour hand comes round to six o'clock. Communication between the poles will thus be effected, and the bell will ring until you unclamp the pointer. This, at any rate, insures your getting up, and lessens the risk of taking a second "nap," as often happens with some kinds of alarum. Of course, I am supposing the dial to be a non-conductor, such as enamel or paint. If the clock be not flat at the top, the block and pointer could be placed beneath the clock. Geo. H. Mason. TELEPHONIC EXPERIMENTS. [15397.]-THE following experiments with the telephone may, no doubt, be interesting to some of the readers of the ENGLISH MECHANIC: The telephone A was connected with the terminals, bc of the primary circuit of a small Ruhmkorf's coil, and the circuit closed by screwing the platinum point tight to the contact-breaker. The line and earth wires were then connected to the terminals de of the secondary coil, and then to another telephone at the other end of the circuit. Conversation could be easily carried on by means of the telephone thus arranged, although the voice |