which the deposit is made, the solution will not keep saturated. On the other hand, if the anode is very much larger than the positive pole it tends to give a deposit of black powder. Fourth, if zinc is to be coated it should first be coated with copper, as it is difficult to make nickel adhere to zinc, and there is danger that the zinc may be acted on and injure the solution. With solutions and anodes thus prepared and used, the deposition of nickel can be carried on continuously and almost as surely and certainly as the deposition of copper from the common sulphate solution, though the limits of the battery-power which may be used are narrower. The metal deposited is compact, cohesive, and tenacious. It may be deposited of nearly uniform thickness over any surface, however, large. The deposited metal is capable of being annealed by a heat below a lowred heat. It then becomes flexible, malleable, and ductile. The deposit may be made of any required thickness, either to furnish effectual protection to the metal on which it is deposited, or to be removed and used separately from the surface on which it may be deposited." In the same year, but a few months earlier than the date of the patent above referred to, a patent had been granted to the same inventor for the use of a solution of the sulphite of nickel in a solution of sulphite or bisulphite of ammonium. This solution is identical, apparently, with that which M. Roseleur claims to have used as early as 1849, with excellent results, in the establishment of M. Kraintz at Grenelle, but which as I glean from a "Notice supplémentaire sur le Nickelage" which he has lately issued, he has discarded in favour of the double sulphate. The Adams patents were the first on the subject of nickel plating in the United States, and the rapid development of the art to the proportions of an important industry, which took place within a few years thereafter, gives colour to the claim that Mr. Adams is entitled to the credit of being the originator of the art of nickel plating. I have elsewhere pointed out that the true explanation of the remarkable growth of this art is to be found in the substantial improvements in the metallurgical treatment of nickel, by which anodes of any desired size, and of great purity, were placed at the service of the nickel plater; and more especially in the invention and improvement of the dynamo-electric machine, which has made the nickel plater independent of the uncertain and troublesome voltaic battery. Had it not been for the want of these two important elements of success in this branch of the galvanoplastic art, plating with nickel would unquestionably have been extensively practised, years before it actually assumed a position as a successful and popular industry. It cannot be denied, however, that Mr. Adams, by directing the attention of technologists to the excellent qualities of the double salts of nickel and ammonium, at a time when everything was ripe for the new industry, materially assisted in calling it into existence, and in assuring its commercial success. The years immediately succeeding 1869 were very prolific of inventions relating to the art of nickel plating; many of which, however, were comparative valueless. I select for notice a few that appear to have meritorious features. Formulæ for nickel-plating solutions. Double sulphate of nickel and Water Parts. 5 to 8 100 Dissolve the nickel double salt in above quantity In 1879, Edward Weston, of Newark, N. J., noticing its favourable influence upon the electrodeposition of nickel, secured a patent for "the electro-deposition of nickel by means of a solution of the salts of nickel containing boric acid, either in its free or combined state. The nickel salts may be either single or double." Mr. Weston affirms that the presence of boric acid prevents the deposit of sub-salts upon the articles in the bath, of water with the aid of heat. Cautiously add which is apt to occur if the bath is not in proper ammonia, or the sulphate of ammonium, until the working condition; he claims, furthermore, that solution is neutral to testpaper. This solution should its addition, in either the free or combined state, to be maintained as nearly neutral as possible in use. a solution of nickel salts diminishes the liability to This is commonly known in the United State as the the evolution of hydrogen when the solution is used Adams solution. It is in very general use by for the electro-disposition of nickel, and increases nickel platers throughout the United States, and the rapidity of deposition, by permitting the use of yields, were properly managed, excellent results. a more intense current, and improves the character of the deposit by rendering it less brittle and increasing its adhesion. The results of extended practical trials of Mr. Weston's formula, made by the writer, have convinced him of the substantial correctness of the claims of this inventor. Where the double sulphate of nickel and ammonium is used the addition of boric acid in the proportion of from loz. to 3oz. to the gallon of solution gives a bath less difficult to maintain in good working order, and affords a strongly adhesive deposit of nickel. The deposited metal is dense and white, approaching in brillancy that obtained from the solution of the double cyanide. In 1880, J. Powell, of Cincinnati, patented an electro-depositing solution" composed of the pyrophosphate of soda, phosphate of nickel, the bisulphite of soda, and citrate of nickel and ammonia." In the same year C. G. Pendelton, of New York, patented the use of an acid solution of the acetate of nickel. The inventor emphasises the caution that this solution must always be kept acid. The metallic strength of this solution is fully maintained by the solution of the anodes, and the bath consequently requires no additions of fresh salt. An interesting suggestion is that patented in 1880 by Mr. Powell, and which covers the use of benzoic acid in nickel-plating solutions. In describing his improvement Mr. Powell calls attention to the fact (?) that simple salts of nickel cannot be used on accout of their failure to yield a regular deposit. He claims to have discovered the addition of benzoic acid to any of the nickel salts, arrest in a marked degree the tendency to an imperfect deposit, and prevents the decomposition of the solution, and consequently the formation of subsalts. The amount of benzoic acid necessary to be added to the bath for this purpose is said to be oz. to the gallon of solution. He, therefore, claims an electro-depositing bath consisting of a soluble salt of nickel, its solvent, and benzoic acid." This bath is reported to give very satisfactory results. In the same year, Mr. J. H. Potts, of Philadelphia, was granted a patent for an improved solution for the electro-deposition of nickel" consisting of the acetate of nickel and the acetate of lime, with Mr. the addition of sufficient free acetic acid to The acetate of calcium he prepares by treating No. 2. Double sulphate of nickel and ammonium. Boric acid (refined) Parts. 10 24 to 5 150 to 200 (Weston's solution.) The superiority of this solution is generally acknowledged. The deposited metal, as previously remarked, is almost silverwhite, dense, homogeneous and tenacious, and the solution maintains its excellent working quality very unformly in long-continued service. The nickel salt and boric acid may be dissolved separately in boiling water, the solutions mixed, and the volume brought up to that of the formula, or the two components may be dissolved together. No. 3. Acetate of nickel.. Parts. 24 24 100 To each gallon of this solution add 1 fluid ounce acetic acid. 1.047 sp. gr. To prepare this bath, dissolve about the same quantity of the dry carbonate of nickel as that called for in the formula (or three-quarters of that quantity of the hydrated oxide) in acetic acid, adding the acid cautiously, and heating until effervescence has ceased, and solution is complete. The acetate of calcium may be made by dissolving the same weight of carbonate of calcium (marble dust) as that called for in the formula (or one half that quantity of caustic lime), and treating it in the same manner. Add the two solutions together, dilute the volume to the required amount by the addition of water, and then to each gallon of the solution add a fluid ounce of free acetic acid, as prescribed. (Potts' solution) Sulphate of nickel. Parts. 6 3 3 14 200 In 1877, John Unwin, of Sheffield (England) devised an ingenious process of preparing the double salts of nickel and ammonium. This consists in preparing a strong solution of sulphate of ammonium, by dissolving the salt in hot water in the proportion of about 4lb. of the salt to each gallon of water, then filtering if necessary, and allowing the liquid to become cool. The double sulphate of nickel and ammoniun is obtained by adding this solution to one of the sulphate of nickel. The novelty of Mr. Unwin's process, how- This solution, which I have worked with under ever, resides in the fact that he does not stop a variety of circumstances, is in many respects an the addition of the sulphate of ammonium when excellent one. It gives satisfactory results, without sufficient has been added to combine with all the that care and nicety in respect to the condition of sulphate of nickel present, but continues to add it the solution and the regulation of the current which in farge excess. "I do this," says Mr. Unwin, are necessary with the double-sulphate solution. "because I have discovered that the double sul- The metallic strength of the solution is fully mainphate of nickel and ammonia is far less soluble in tained, without requiring the addition of fresh salt, the solution of sulphate of ammonia, than in pure the only point to be observed being the necessity of water, so that it is precipitated from its solution in adding from time to time (say once a week), a water on adding sulphate of ammonia. I therefore sufficient quantity of acetic acid to maintain a discontinue adding the solution of sulphate of am- tinctly acid reaction. It is rather more sensitive to monia, continuously stirring, until the liquid loses the presence of a large quantity of free acid than nearly all its colour, by which time the double to the opposite condition; 28 in the former sulphate of nickel and ammonia will have been pre- condition it is apt to produce a black decipitated as a light-blue crystalline powder, which posit, while it may be run down nearly readily settles to the bottom of the vessel. I then to neutrality without notably affecting the Prof. Boettger; it is said to be well suited for the pour off the liquid from the crystalline precipitate character of the work. The deposited metal is purpose of amateurs, inasmuch as it gives good reof double sulphate of nickel and ammonia and wash characteristically bright on bright surfaces, and results with a platinum anode. It is worked at a the latter quickly with a strong, cold solution of quiring but little buffing to finish. It does not ap- It requires renewal from time time, as it becomes temperature of 100° Fah., with a moderate current. sulphate of ammonia as often as I con- pear, however, to be as well adapted for obtaining sider necessary for its sufficient purification." deposits of extra thickness as the commonly used impoverished in nickel, by addition of fresh nickel By this procedure it will be perceived, the double sulphate of nickel and ammonium. On salt; it must also be kept alkaline by the occasional double salt of nickel and ammonium is the other hand, its stability in use, the addition of ammonia. thrown down in a pulverulent, granular variety of conditions under which it will work condition, readily soluble in water, and therefore satisfactorily, and the trifling care and atready for use in the depositing vat, without waiting tention it calls for, make it a useful solution for for the tedious process of crystallisation. nickeling. Watt recommends for ordinary purposes the following solution, which he affirms will give in careful hands very good results. "Take, say, 2oz. of pure nickel, dissolve in hydrochloric acid, taking care not to have an excess. A gentle heat will assist the operation. When dissolved, dilute the solution with 1 quart of cold water. Now add ammonium gradually, until the solution is quite neutral to test-paper. Next, dissolve loz. of salammoniac (chloride of ammonium) in water, and mix this with the former solution. Lastly evaporate and crystallise slowly." The resulting salt will be the double chloride of nickel and ammonium. It is one of the earliest solutions used for nickel-plating by Smee and Gore, and is affirmed by these writers to give good results. Watt has also obtained excellent results with the double chloride. According to Smee, the simple chloride of nickel will yield a deposit having a very brilliant lustre. I can unequalifiedly confirm the statement of Gore that the electro-deposit obtained from a solution of the double cyanide of nickel and potassium is nearly equal in whiteness to silver." I have obtained deposits with this solution, of such extreme whiteness and beauty as to deceive even an expert on casual inspection into the belief that they were silver. The bath, however, rapidly loses its activity and runs down, and is so difficult to manage that it is impracticable for general use. This, at least, is the opinion I have reached after many trials of it. I am informed, nevertheless, that it is successfully used on the large scale in certain nickel-plating works in this country, though I have not been able to substantiate the fact. THE SCIENTIFIC NEWS. An interesting subject for investigation was suggested by M. Certes in a paper read recently before the Academy of Sciences of Paris on the HE death is announced of M. Boutigny cultivation of the sedimentary matter brought up (d'Evreux) in the eighty-sixth year of his from great depths by the dredgings of the Traage. He was the discoverer of the spheroidal railleur and Talisman. His object is to determine state of water, and investigated many of the if the absence of plants and animals in the depths phenomena connected with the action of high of the sea is due to the presence of microbes temperatures on matter. He was a corresponding analogous to those which produce transformation member of the Academy of Medicine of Paris, of organic into inorganic matter on the surface and was formerly president of the Pharmaceutical of the earth. Society of Paris. Mr. W. Saville Kent, F.L.S., has been appointed Inspector of Fisheries to the Tasmanian Government, and leaves shortly for the scene of his work, which will consist mainly in extending the introduction and distribution of the Salmonidae and the cultivation of the oyster. A systematic investigation of the marine fauna of Tasmanian waters, with the view of turning to a profitable account those that can be utilised, also forms a feature in the programme. Mr. Kent will endeavour to establish a marine laboratory which will no doubt be of great advantage in Australasia. At the meeting of the Bristol Naturalists' Society last week, Prof. Silvanus Thompson read Complaints are beginning to be made of the manner in which the MS. indices at the Patent Office are kept. About 6,000 applications have already been entered this year, and it is important that the indices should be carefully made up; but it is absurd to find under "boats" such simple domestic utensils as "butter boats," and ship's fenders classed as "fireirons." Literal errors are numerous, and yet the staff of the Patent Office is recruited from those who are supposed to have passed an examination in what are known as school subjects." M. Fremy is endeavouring to establish a marine laboratory on the coast of Algeria. Mr. Clement L. Wragge is preparing for press We learn by the last mail from Adelaide that an account of the observations taken by him during his voyage to Australia. USEFUL AND SCIENTIFIC NOTES. Cementing Brass on Glass.-Puscher recommends a resin soap for this purpose, made by boiling 1 part of caustic soda, 3 parts of colophonium (resin) in 5 parts of water and kneading into Naval Architects was held last week, and a The annual meeting of the Institution of it half the quantity of plaster of Paris. This cement is useful for fastening the brass tops on glass lamps, number of interesting papers were read, the most bears heat very well, and hardens in one-half or as it is very strong, is not acted upon by petroleum, notable of which were the description of the three-quarters of an hour. By substituting zinc Riachuelo by Mr. Samuda, and that of the elec-white, white lead, or air-slaked lime for plaster of trical launch by Mr. Yarrow. With regard to Paris, it hardens more slowly. Water only attacks the latter it was thought that electric propul- the surface of this cement. Wiederhold recomTo prepare this bath make a solution of sion, from the absence of noise, would be of great mends, for the same purpose, a fusible metal comany sait of nickel, and add cyanide of advantage in the case of small torpedo boats, posed of 4 parts of lead, 2 parts tin, and 24 parts potassium solution so long as a precipitate which would be able to harass an enemy's fleet bismuth, which melts at 212 Fahr. The melted continues to be formed, being careful to avoid Several purely technical metal is poured into the capsule, the glass pressed during the night. adding an excess. Then remove the liquid either by decantation or filtration; and after papers were read, of special interest at the pre into it, and then allowed to cool slowly in a warm several washings dissolve the precipitate almost sent time, and some more or less popular which place.-Polyt. Notizblatt. to saturation in cyanide of potassium solution. have a wider application than the comparatively Make a completely saturated solution, and add a narrow confines of steam navigation, such as the small quantity of free cyanide of potassium. The application of hydraulic machinery, and the use brownish-red solution is then ready for use. of cast steel for crank-shafts. With regard to sulphate of nickel and ammonium is used most more than 50 per cent. of the power originally It may be added, in conclusion, that the double the electrical launch, it was pointed out that not generally by electro-platers with nickel. employed to charge the batteries could be recovered and put on to the screw-shaft, but for special purposes a small plant could be made to yield a high power for a short time. (To be continued.) Estimation of Sulphur Compounds in Coal Gas-Prof. J. A. Wanklyn writes:It has been pointed out by more than one chemist that the referees' method of determining the amount of sulphur existing in coal gas is very far from being perfect. The sulphurous acid, which is formed by the combustion of the sulphur compounds, is not placed by the referees under conditions which insure that none of it shall escape oxidation; and it is only too true that one and the same sample of gas will furnish different results in the hands of different operators. An improvement of the referees' method is urgently called for. The following modification has been practised in my laboratory, and appears to meet the requirements of the case. Employing the apparatus which is now so well known as that recommended by the referees, I abandon the use of carbonate of ammonia and of ammonia in all shapes, and I place iodine amongst the glass balls in the upright cylinder. I employ about five grammes (or 75 grains) of iodine for each determination of the sulphur in five cubic feet of gas. The reaction which takes place very well known-viz. : SO2+H2O+I2=SO3+2HI As an extra precaution against loss of sulphuric acid, I insert a long strip of filter paper into the long slanting tube, and from time to time pour in small quantities of distilled water, so as to keep the filter paper moist. I find that the gas may be burnt at least twice as fast as the referees recom M. G. Towne gives, in Comptes Rendus, an account of his method of applying incandescence lamps to astronomical instruments, apparently under the impression that the idea is novel. One of his lamps, which is stationary, is placed in a copper tube 8cm. long and 4cm. diameter, and at the orifice of the tube which faces the lens a glass is fixed, which prevents the heat from penetrating into the lens. At the other extremity is a copper plug, upon which the conductors bear with slight friction. The tube is placed opposite a reflecting disc, which is pivoted, and by means of a button the light can be regulated to any desired degree. The other lamp is placed in a special lantern, and serves alternately for reading the verniers and for illuminating the lines of the meridian circle. M. Towne uses a Trouvé bichromate battery, and regulates the light by the immersion of the zinc plates and the alteration of the reflecting diaphragm. The scientific friends of Signor Sella have determined to place a bronze wreath on his tomb, and Prof. T. M. Hughes, of the Woodwardian Museum, Cambridge, will receive subscriptions. a The Salicylic Acid in Wine.-The Syndicate of the Bordeaux wine merchants has fought in the various lawcourts of France to maintain the right of preserving wine by the aid of salicylic acid. chants' syndicate has been bold enough to petition Though the Consulting Committee of Hygiene for France has condemned this practice, the wine merthe French Chambers on the subject. tribunals have convicted and sentenced severely persons proved guilty of introducing salicylic acid into wine; but the Court of Appeal of Bordeaux, yielding to local influence, sanctioned the practice. sion, to the Cour de Cassation at Paris, and the The matter was therefore referred, for final decisentence pronounced laid down the principle that, though salicylic acid when used in certain propor tions was not likely to injure any alimentary substance, nevertheless the sale of any wine or food containing even the smallest quantity of this acid must be rigorously forbidden. The reason for this very necessary injunction is easily understood. Wine, especially, changes hands so frequently, that it would be impossible to check the amount of salicylic acid introduced if the use of any quantity whatsoever was allowed. The admixture of Spanish and Italian wines with the caused by the phylloxera have rendered the ravages French wines a matter of absolute necessity. But the former wines contain so large a proportion of sugar that when they reach the consumer and are exposed to the heat of apartments, &c., a second fermentation is likely to set in. To prevent this, antiseptics, and especially salicylic acid, have been used in such large quantities, that Dr. Brouardel detected as much as one gramme in a litre of wine. These facts are of almost as great interest on this as on the other side of the Channel; for, now that the Court of Final Appeal has rendered the sale of France, it is more than probable that these wines wines containing salicylic acid a penal offence in will be sent over to England.-Lancet. Calcutta International Exhibition. The Park Hill railway cutting at Croydon gave rich yield of fossils from the Woolwich and Reading beds, which have been described by Mr. Klaassen in the Proceedings of the Geologists' Messrs. F. Leroy and Co., of Gray-street, Commend. The gas in my own laboratory at West-bird and an ulna of the rare Eocene mammal their Bengal agents, a second class certificate and a Association. He found the bones of a gigantic mercial-road, London, E., have obtained, through minster has furnished 18.6 grains of sulphur per named Coryphodon. The great engineering bronze medal for their non-conducting composition 100 cubic feet. I have to caution gas managers against using both ammonia and iodine at the same difficulties experienced in making this cutting for preventing radiation and loss of heat. These time, and so producing the terrible iodide of render it unlikely that any similar opportunity are the only awards granted for any covering of nitrogen." will occur again. steam-heated surfaces at this exhibition. ENGLISH MECHANIC AND WORLD OF SCIENCE: No. 994. LETTERS TO THE EDITOR. [We do not hold ourselves responsible for the opinions of the ENGLISH MECHANIC, 81, Tavistock-street, Covent-garden, W.O. All Cheques and Post-office Orders to be made payable tr • In order to facilitate reference, Correspondents, when "I would have everyone write what he knows, and a 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. VEGETARIANISM-TRUE PLANE SUR- Tortoise man") ? APRIL 11, 1884. day and night to be delivered from "eminence" on point will be rendered parallel by the lens L, and who lost his tail. It is the way with all fanatics and 53357, p. 88) can scarcely do better than to obtain be directed. At C M. Montigny interposes discs of the real one to which the telescope may happen to glass, coloured according to Chevreul's chromatic scale, and so tinges his artificial images with the various colours it includes; but he also suggests (I do not know whether he has tried it practically) I P 0 Τ very fine [22553.]-IF Mr. W. Henley Richmond (letter 22474, p.35) is content to accept letter 22530 (p. 82) as in any sense a reply to his demand for the names of eminent men who have been vegetarians, verily, like the old Scotchwoman in the parable, he must be "thankfu' for sma' maircies." It may not be wholly uninstructive to take Dr. Allinson'seminent men 99 seriatim, and see exactly the weight of the argument derivable from his selection. The Essenes, we know, were ascetics; but who told Dr. A. that they were vegetarians? Pythagoras, scarcely one single thing is known given place (say Greenwich), find the Sun's right As for "Marienberg" (query 53368, p. 89) should get of his personal history. a celestial globe, elevate it to the latitude of any Clement of Alexandria, Eusebius, and so Diodorus Siculus, to Bentley, Stanley, and Thirlwall, only differ ascension and declination from Whitaker's Almanac, among themselves 84 years as to the date of turning the globe on its axis, let him note, by the on and stick a small circular piece of paper or a wafer his birth! I suppose that Dr. Allinson knows the brass hour circle, how long the sun takes to pass on the spot indicated by these co-ordinates. Now, legend about his stopping the ox from eating beans from its point of rising from beneath the wooden by a whisper? What odd vegetarian practice! By horizon to the point of setting. Having ascerZeno, does your correspondent intend to signify tained this, he may elevate the globe to a different that the white light of the electric arc might be Zeno the Stoic, or Zeno of Elea (the "Achilles and latitude altogether (suppose Calcutta). Once more passed through a prism (or series of prisms?) of did mainly live on figs, bread, and honey. in describing its path from its rising to its setting, ing colours caused to traverse the lens L as before. Zeno, the Stoic of Citium, let him observe how long his paper spot occupies great dispersive power, and any one of the resultDr. Allinson can only rely on the inscription over and he will see at once that it is the latitude of a do not myself see why for the electric light at E the entrance to the garden of Epicurus to show that place which makes the difference in the (local) should not be substituted a very minute, accurately he was a vegetarian. Authority, too, is needed for times of sunrise and sunset, and not the longitude pierced hole in a metal plate. Perhaps a thin leaden the assertion that Plutarch did not eat flesh. Of at all. German almanacs give the times of sunrise plate perforated with the point of a course, Porphyry wrote the treatise " Twv εμúkov"; but upon what conceivable autho- English almanacs show the hours of sunrise and good kerosine lamp. This, if placed accurately Tεpi άroxйs and sunset in Berlin, using Berlin Mean Time. needle might do, illuminated from behind by a rity is it asserted that St. Matthew ate no meat? sunset at Greenwich, employing Greenwich Mean in the focus of L, would make a nice little star Beyond the fact that he was a Roman tax collector, Time. Berlin is just 1° north of Greenwich, so image, and films of coloured gelatine carefully less than nothing is known about him. I have that the diurnal path of the sky on the same day of selected by the spectroscope might be placed at C. heard of Musonius, the Stoic; but, probably owing the year differs but little at the two places. The This, however, is only a notion of my own, which I to my neglected education, I am ignorant of the difference between Greenwich and Edinburgh throw out for what it is worth. "painter." That Brahmins were-and are-vege- would be much more perceptible. tarians is but too true; millions of them never touching, or being able to procure, anything but rice with a pinch of curry powder. To what an intellectual condition this diet has reduced them, and what moral and physical courage it has developed in them, let anyone who has ever been in India say. Dr. Allinson's authority for his assertions with reference to Cyrus, as also to the training of the Greek gymnasts, &c., is desirable. Before passing to his modern instances," I must express my great surprise that he has omitted one eminent" vegetarian, of which authentic historical record exists. I mean, of course, Nebuchadnezzar (Daniel iv. 33). Coming now to more recent times, nothing can be more unfair than to speak of a man being "a vegetist part of his life." This means anything, and proves nothing. Sir Isaac Newton's insanity is unhappily matter of history (reply 53288, p. 87). Halley may have been (I don't say was) a vegetist; at any rate he bad rickets, and led a protracted life of suffering. Sir Richard Philips was an anti-Newtonian quack, whom it is an abuse of language to describe as "eminent." As for the string of utter nobodies with which Dr. Allinson concludes his penultimate paragraph, I am not even yet convinced that he is not poking some very clumsy fun at Mr. Richmond. "Dr. Nichols": Is this the man who keeps the "Food of Health" shop? nalist": Is this the person who exploitéd those "Burns the Spiritscandalous impostors-Herne and Williams, to say nothing of other Media"-until they were found out? A very "eminent" man truly! Anti-vaccination and teetotal fanatics et id genus omne complete the list;-with reference to which I would simply say that if these be "eminent" men, I should pray 66 to redeem the promise made (on p. 76) to Mr. Baird tions of the Comets of 1880, 1881, and 1882, of the Gemmill to observe the list of stars which he gave highest interest to all who are engaged in the study Since writing letter 22505, I have endeavoured nati Observatory will be found a series of observa on p. 55, with a view to the determination of the of cometary physics. The first part of the work In the volume recently issued from the Cinciacolours which they present to my eye. The result, is devoted to the determinations of the co-ordinates so far as I have been able to go, is this:-Arcturus of position of these bodies, made, of course, with a appeared of a reddish white (the night being rather view of ascertaining their respective paths through hazy); Procyon (on a brilliant night), very pale the sky, and hence, obviously, their orbits. The yellow; Regulus, cream colour; Capella, white, second section of the volume will probably appea! with a very faint tinge of yellow; Rigel, almost to a wider public, dealing as it does with the physi white, with very slight tinge of yellow: there is cal structure of these bodies. I can personally a kind of blue rim round the disc of this star. testify to the extreme accuracy of many of the each case I employed the same instrument and eye- of this portion of the book are illustrated. Notpiece; an achromatic of 4in. aperture, with a ably is this the case as regards Comet b, 1881, the a Orionis, reddish orange; a Tauri, orange. In beautiful drawings with which the descriptive parts power of 160 linear. are all comparable inter se, and are trustworthy as my own sketches made on the same nights at differential ones. Colours, has Mr. Gemmill ever heard of the in- the singularly close agreement between delineations Hence, these observations engravings of which I have been comparing with genious contrivance for determining the colours of executed so many thousands of miles apart, by By the bye, writing on Star the telescope; with no little gratification at finding stars devised by M. Montigny, of Brussels, to observers with instruments differing so greatly in whose classical referred in letter 22395, Vol. XXXVIII. p. record of the remarkable physical changes under557? researches in Scintillation I size and power. As an absolutely trustworthy but it seems to me to hold out the promise would be hard to exaggerate the importance of the of being very effective. I have not seen the apparatus myself, gone by the strange bodies of which it treats, it should make its principle intelligible. To the should be in the library of all who are interested in object end O of an achromatic telescope is fitted an the physical structure of Comets. I should suppose The annexed figure volume brought out by Mr. Herbert C. Wilson. It prism P in front of the object-glass. Supported curable through an American bookseller in London. arrangement carrying a very small total-reflection-although I do not certainly know-that it is proby the arm, shown in the sketch, is a second totalreflection prism P', like the first, towards which it write-the first one issued from the Astro-Physica reflects rays following direction ELP. At L is an Observatory of Herr Eugen von Gothard, & achromatic lens, and at E, in its focus, M. Mon- Herény in Hungary. Celestial physics is a subject Another fine volume, too, lies on my table as I tigny employs the electric light to produce a lumin- which would appear to exercise a peculiar attraction ous point. Quite obviously the rays from such a for the Hungarian mind. The noble work done by Dr. Von Konkoly at O'Gyalla, is familiar to astronomers in every part of the civilised globe; and judging from this first Volume of Observations, he would seem to have a formidable competitor (or rather I would say a worthy coadjutor) in Herr von Gothard. In fact the latter gracefully and gratefully expresses his obligation to Dr. Von Konkoly for the invaluable aid he has rendered him in the prosecution of his design. The chief instrument in the Herény Observatory is a 104in. Browning reflector, mounted equatorially, and, of course, driven by clockwork. The transit is a small portable one by Reichenbach, with a Fraunhofer object-glass, and there are two astronomical clocks. The spectroscopic and inicrometrical apparatus, and that for celestial photography, is of a very elaborate description. There is a laboratory fitted with the most approved apparatus for physical research, a library, and a complete set of meteorological instruments. The three brothers, Herren Eugen, Alex., and Stefan von Gothard, together with Joseph Molnár, form the staff of the observatory. A fine series of sketches of Jupiter, made during the year 1882, adorn this volume; both that planet and Mars having been sedulously observed. In addition, too, to the spectroscopic observations which form a leading feature in the work of the observatory, watch was kept upon the solar eclipse of 1882, May 16th; on the last transit of Venus, and on the August shooting stars, the results of all which are given. Here, again, is one more example-were such needed-of what private enterprise and singlehearted devotion to the search of truth can, and does, effect for science. Why, there is more real work done at places like O'Gyalla and Herény in a month than there is at Brompton in a year. Men like Von Konkoly or Von Gothard would as soon think of going to the Hungarian Diet to have their "researches" "endowed as they would of standing hat in hand in the road to beg quarter-gulden pieces of the passers by. To the eternal disgrace of our own country, it has been reserved for England to produce a cadging ring of scientific mendicants, who from their head-quarters at Brompton send forth their whining appeal to be paid for work before they do-or even are able to give the slightest assurance that they can do-it. angles to which the prisms in the Merz polarising its shadow-cone is a minimum; but every day on JUPITER. [22554.]-I SEND a list of observations of the red spot and white equatorial spot on Jupiter, obtained here since the middle of January : RED SPOT. Date. Jupiter is daily assuming a less favourable position for observation of detail, and it is very important that during the period remaining available the chief markings should be reobserved as frequently as possible. There is little doubt that the white spot will still be visible when the planet (after conjunction) becomes well presented in the morning sky at the end of next S-ptember, but the further existence of the red spot is extremely questionable. Under these circumstances, it is essential that the latter be followed as long as practicable during the present apparition. Below give a list of the times when the red aud white spots will be presented on or very near the central meridian of the planet, and shall be much interested in seeing some further observations reported in your columns: h. April 15...... 11:4 12.6 18. 8.9 16. 8.3 11 10 82.6 90.2 5.... 8:0 4...... 9.2 I would commend the careful study of the 14th verse of the xvth chapter of St. Matthew's Gospel o the consideration of the writer of letter 22534, on ). 99. The Nautical Almanac was quite right, and Mr. Binns is utterly wrong. The fact is that he aistook the quasi-circular white patch on the great outhern dark belt of Jupiter for his IVth satellite, nd the satellite itself for its own shadow! The nost rudimentary acquaintance with the subject would have shown him that with Jupiter within a ittle more than a month of coming into quadrature with the sun, at least 10 hours must elapse between the time of transit of his outer satellite, and that of The daily rate 878 46° corresponds to a period of its shadow. When the planet is in or very near 9h. 50m. 7-42s., which Mr. Marth derived from the opposition, as he was on the 20th of last January, observations made between October, 1880, and both this satellite and its shadow may be simul-August, 1882; but the motion has exhibited a simiobservable on the 22nd of that month; but to allege the last seven months the time of rotation has inaneously visible on his disc, a phenomenon actually lar retardation to that of the red spot, for during that it could by any conceivable possibility have creased to 9h. 50m. 128. Between Feb. 23 and been witnessed on March 12th is, not to speak dis- March 15 of the present year the white spot was courteously, sheer nonsense. unusually bright and large; but the last time I saw it (on March 24), it was recorded as faint and small. Judging from the successive appearances of this object during the last few oppositions, there is every probability that it will remain visible for a lengthened period. As to the present aspect of the red spot, it still lingers in a state bordering on utter obliteration, and its S.E. side has recently become involved with the faint belts in higher latitude. It remains to be seen whether this is the prelude to its final extinction. I much fear that I can give no trustworthy rule or rules which shall enable A Foreign Subscriber " (query 53388, p. 111) definitely to identify Jupiter's satellites, save that III. is the biggest of them all, and IV. seems to shine with, if I may so express it, a darker or greyer light than the others. The worst of it is, though, that the light of these moons is variable, and this introduces a serious element of difficulty. If my querist has access to the Nautical Almanac, or to Whitaker's Almanac, he will find diagrams of the positions of all four satellites in either of these works for a given hour on every day in the year on which Jupiter is visible. These will enable him to recognise the satellites with certainty at the time specified; and he may then try so to familiarise his eye with their physical aspect as to know them again when he sees them. The "books on astronomy" to which "H. A." refers in query 53389 (p. 111) tell us what would happen if the sun were to remain stationary on the equator for the whole of the day on which he is said in the almanacs to enter Aries"; and if our atmosphere were removed. Inasmuch, however, as neither of these conditions can by any possibility obtain, we are brought face to face with such discrepancies as puzzle your correspondent. As a matter of fact, the sun is moving rapidly in declination when he crosses the equator, and the effect of refraction is to cause him to rise some 3m. 448. earlier, and set 3m. 44s. later, in these latitudes than he would were our aerial envelope non-existent. "H. A." presumably knows that the sun was not on the meridian on March 18th until 8m. 1s. after noon. In reply to "Solar" (query 53398, p. 111), the We are all much indebted to Mr. T. G. Elger for = 13..... 9.6 15...... 10.8 The red spot at intervals of 29 rotations days crosses the C.M. at the same times as before. The transits of the white spot, after 61 rotations 25 days, also recur at the same approximate times. It is useful to remember this as affording a ready means of computing the transits sufficiently exact for purposes of observation. Bristol, April 5. W. F. Denning. COLOURS OF 23 STARS OBSERVED Colours of 23 stars observed with the 3in. refractor, his remarkably effective drawings. He will, how-10. 3 Geminorum Colour. pale orange orange (var). T. E. Espin. Observatory of the Liverpool Astronomical Society, With regard to the black transit of Satellite IV. |