majority of visitors gather their impressions of Madeira from a limited halt in the Bay of Funchal, or from a winter sojourn on its south side, yet fine as its coast line and peaks are seen to be, they are no more comparable to the grandeur of the northern side than the cultivated banks of the Rhine are to the gorges of the Yosemite. The south side is almost destitute of forest growth, except the introduced sweet chestnut, oak, and maritime pine, for the native juniper and dragon trees are almost extinct, but in crossing the dividing ridge another world is entered. Here all but the highest peaks are clothed with densest virgin forest. The naturalist may penetrate at will the wildest gorges, for the only paths into their recesses are the beds of half dried torrents. The common distinctive feature of all these gorges is the precipitous nature of their sides, which time seems not yet to have weathered into angles of repose. The verticality is everywhere appalling, yet giant evergreens cling to every nook and crowd on every terrace. Some of the laurel tribe reach immense girth, and are quite inaccessible to the woodman's axe, rotting as they stand, and forming soil for carpets of Killarney, filmy, and hares-foot ferns. The warm, moist, and shady valleys form a paradise for ferns, the Dicksonia, Woodwardia, and Asplenium rivalling each other in size. The botany of the island is of great interest, especially in its relations to that of Europe and Africa; but the visible fauna, except Mollusca, is meagre, and the comparative absence of birds and butterflies is felt. Beyond the foreground of vast walls of red and brown rock, often 3000 to 4000 feet high, clothed and softened by dark green foliage, are peaks weathered into most fantastic forms, and rising to 6000 feet. But if this grand scenery could become monotonous, there are English moorlands on the Paul da Serra, barren tracts of rock at the extremities of the island, cultivated country with lanes hedged by fuchsias and hydrangeas at Camacha. The coast-line is magnificent in the extreme, one headland on the south presenting a vertical cliff to the sea of 2000 feet, and another, a mountain clothed with myrtle on the north, being scarcely inferior to it. The ascent of some of the peaks might tax even an experienced Alpine climber's nerves; but the effect of ocean rising to the skies like a blue wall all round is very striking when seen for the first time from a lofty island peak. In summer the heat is not oppressive among the mountains, and now that the fares are no longer unreasonable, one with an overtaxed brain seeking rest might make a worse choice than Madeira for a ramble. To him Miss Taylor's exhaustive book is inexhaustible, and the itineraries in it, sketched by Mr. Charles Cossart, invaluable. No mention of Madeira is complete without allusion to its staple produce-wine. The export seems never to have exceeded 20,000 pipes annually, and though this was reached as early as 1750, yet this is far below the producing power of the island. The vines, destroyed by Oideum, have again severely suffered from Phylloxera, but the shipments, owing chiefly to the persistent efforts of Messrs. Cossart Gordon, are steadily recovering. It cannot be too widely known that Madeira is a pure wine, for at the price of grapes there, there is no incentive to use anything but grape juice in its production, though Madeira is exported to other wine countries, presumably for manufacture into sherry. The retail price is only artificially maintained by a pretended scarcity. J. STARKIE GARDNER Tschermak's Lehrbuch der Mineralogie. (Vienna Alfred Hölder.) Part II. IN this part of Prof. Tschermak's text-book the discussion of the optical and physical characters of minerals is continued and concluded in a manner more scanty than was perhaps to be anticipated from the first part. The results of many of the most recent additions to our knowledge of the structure of mimetic and twin-crystals, such as milarite, microcline, &c., as shown by their optical properties, are, however, included. In the chemical introduction which follows, too much space is devoted to the exposition of the fundamental principles of chemistry, such as those of equivalents, atoms, and the theory of types; as also to the principal simple tests for the various elements. A fair knowledge of chemistry is absolutely necessary to the mineralogist, and Prof. Tschermak might well have expected his students to bring such a knowledge with them. In this case his exposition is unnecessary, while if the student is ignorant of chemistry, it is hardly likely to be adequate, and it undoubtedly diminishes the space available for the principles of isomorphism and polymorphism. Considerable space is given to the description of the situations in which minerals are found, and of their associations in beds and veins. Another chapter is devoted to mineral genesis and to the decompositions and transformations which minerals are liable to under the action of natural agencies. These subjects, common to the mineralogist and geologist, are apt to suffer through being relegated by each to the other, and we are glad to see the importance attached to them by Prof. Tschermak. The systematic description of the principal minerals is to occupy the whole of the third part. This volume extends as far as the elements and sulphides, and gives us a foretaste of what is to come. The descriptions are well done, and give much more information than the ordinary text-books do. This information is, moreover, given in general language, and the different forms are better and more fully illustrated than is usually the case. The minerals discussed are those of importance either from their utility, the frequency of their occurrence, or their scientific value; and the selection, from this point of view, is well made. LETTERS TO THE EDITOR [The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts. No notice is taken of anonymous communications. [The Editor urgently requests correspondents to keep their letters as short as possible. The pressure on his space is so great that it is impossible otherwise to ensure the appearance even of communications containing interesting and novel facts.] Scientific Exploration in Egypt Now that we have embarked in a war in Egypt, it is to be hoped that steps will be taken to have a proper staff of scientific explorers attached to the army with facilities for conducting their investigations. There are periods of rest in a campaign during which soldiers and others may be usefully employed in conducting excavations at comparatively slight cost; and difficulties in the way of investigation, arising from the requirements of trade and The deposits of the Delta industry, disappear in time of war. require to be examined. The gravels of the Nile Valley have to be connected with their animal remains. Much has to be done for the earliest and best period of Egyptian art, and the Stone Age of Egypt has to be fixed with certainty, the importance of which cannot be over estimated in connection with the earliest civilisation of the world. I trust also that we shall not rob Egypt of her antiquities to any great extent. It may be useful to complete our typical series to a limited extent, but if Boulak should be happily preserved, I hope it will be preserved for Egypt, and not brought home. Nothing would serve more to prove that we go there to civilise and not to rob. The means of communication are now so easy that all who are intere ted in Egyptology can see it there. Steam and railways have materially altered the requirements of education in this respect. Humanity, and British humanity in particular, now pours through all the great arteries of the world, and people observe and study more abroad than at home. The time has passed when antiquities should be regarded as trophies of war. It is no longer necessary for instruction to hoard up valuable specimens of foreign antiquities in European museums. So long as science has access to the materials of knowledge, that is all that it is necessary to bring away; and national museums, with the limited space at their disposal, should more and more become devoted to local collections. Besides which, it should be remembered that the atmosphere of Egypt preserves antiquities in a way that no other climate can do; and when this fact hereafter becomes fully impressed upon the public mind, the time may come when subscriptions will be raised to take back obelisks and put them up again in their proper places; at any rate we have enough of them weathering and withering in smoke and damp. They are quite out of place in European towns, and seem to hold up a finger of caution to us to proceed no further in that direction. But the opportunity for exploration should not be lost. The French savants did their work thoroughly during their military operations in that country, and it would be shameful if, with the knowledge now at our disposal, the British expedition did not achieve more for the promotion of science than was effected by Napoleon half a century ago. Carlsbad, August 3 A. PITT-RIVERS Francis Maitland Balfour THE memoir of Prof. Francis M. Balfour, published in NATURE, vol. xxvi. p. 313, appears to have been founded, as far as his life at Harrow is concerned, on incomplete information; and I therefore ask your permission to supplement it with my own reminiscences. He entered Harrow School in January, 1865, and when he had reached the upper part of the fifth form in 1867, I was appointed to give instruction in natural science. Although this subject was not taught in any of the forms which Balfour passed through, he soon afterwards eagerly availed himself of the opportunity offered of taking lessons in practical work in biology. This continued without intermission until he left the school for Cambridge more than three years afterwards. He was always ready to spend as many hours as I could give him for work with the microscope and in making dissections. With Dr. Rolleston's "Forms of Animal Life" as guide, he dissected nearly all the typical examples described in that book. In the same way he gained a knowledge of osteology, using a small collection of skeletons which received, for his special benefit, the important additions of a complete crocodile, and an armadillo, several incomplete skeletons of ornithorhynchus, and echidna. No part of comparative anatomy was neglected, but of such an extensive subject, much of his knowledge was necessarily derived from books only, but it was sound, being based on Huxley, Müller, Kölliker, and the like. He had the opportunity also of learning elementary botany. All this work was carried on under conditions with which only a boy of his energy and indomitable perseverance could have coped. At first he had some difficulty in acquiring skill in the purely mechanical details of dissection, but he determined to overcome this difficulty, and he succeeded. The time at his disposal for biology was chiefly the half-holidays, and for such work no marks could be given by his form masters, but on the contrary, it is only too certain that his position in other subjects was affected by his devotion to natural science. Those who managed the affairs of the School Scientific Society in 1868 (two years before Balfour left Harrow), showed their appreciation of his remarkable powers by asking Prof. Huxley to award the prize, which had been offered, through the liberality of Mr. C. J. Leaf, for the best essay written during the previous holidays, being a description of some district known to the author. This unusual step was taken when it was found that the essay sent in by Balfour and another by his friend A. J. Evans, were of such rare merit, that it was felt that they were worthy of being brought under the notice of such a distinguished man as Prof. Huxley. His opinion of the value of these essays fully jus'ified this view. Balfour's knowledge of geology was chiefly gained at home, and no doubt it was of considerable service to him in the com I AM Sorry that I omitted in my brief sketch to point out the benefits which Balfour undoubtedly derived from the science teaching at Harrow, and I am sure my friend Mr. Griffith will understand that it is as far as possible from my wishes to fail in acknowledging the fruit of the labours which he has been carrying on there these several years with such zeal and energy. There can be no doubt, I think, that the training which Balfour had under Mr. Griffith not only helped towards his gaining the scholarship, but materially contributed to making him the man he was. What I wrote concerning his reputation at Harrow, referred rather to what I understood was the general opinion of the school, than to Mr. Griffith's own forecast of what Balfour might become; the latter I have known for a long time to be so sanguine as to come near the truth. M. FOSTER On "getting" Coal by Means of Caustic Lime IN an article on this subject (NATURE, vol. xxvi. p. 299) Mr. William Galloway states that this system "has been found by experiment to be incapable of breaking down a hard rock or shale roof," and is, therefore, not likely to have anything but a limited application. Will you allow me, as one who has had a good deal to do with the new process, to assure Mr. Galloway that so far as it has yet been applied, it has answered every purpose in respect of which gunpowder or wedging have been hitherto used. We have not yet had time to make a series of experiments with the lime process on hard rock, &c., as our attention has been until now turned exclusively to the getting of coal, especially in those mines in which, from their fiery nature, the use of powder has been prohibited. In the Shipley Collieries, where the lime-process has been in constant operation for many months, it is regularly applied to one of the hardest seams in the Midland coal-field, the toughest part of which is that next the roof, and this portion could never be got by wedging in the ordinary way, but had subsequently to be hacked down into slack-by the lime process, however, the coal is parted clean from the roof, along the entire face operated on. In other districts where it has been proved to be a complete success, the places selected for experiment were invariably the hardest in the mine. The cases where the tamping has been blown out are extremely rare, and have been due to causes immediately and easily rectified. We have no reason to believe that the process would fail in its application to the mining of shales, iron ores, &c., and this point will be settled by experiment before long, pending which Mr. Galloway's conclusion on the subject is at least premature. PAGET MOSLEY 81, Warwick Road, Earl's Court, August 10 IN stating that the caustic lime process was likely to have only a limited application in coal-mining operations, it was not my intention to convey the impression, as Mr. Mosley appears to think it was, that the area of its usefulness would necessarily be a small one. On the contrary, I believe it could be successfully employed in getting coal under a large variety of circum stances. Mr. Mosley's connection with the subject could not well be more intimate than that of the gentlemen who supplied me with the information brought forward in the article referred to, and I understood them to say that experiments had been made with the roof of Shipley Collieries, giving results which amply justified the conclusions I stated. Science at the Victoria Hall THE immediate object of the Victoria Hall Committee is to provide healthy amusement in place of the unhealthy sort too often found in places of cheap recreation, and does not appeal specially to scientific men as such. But they have a scheme on hand for next autumn to which I venture to call your attention. They would like to devote one evening in the week for popular lectures, and as a previous experiment they propose to have during October and November a series of very elementary popular addresses on scientific subjects of about half an hour in length, to be introduced in the beginning, or middle, or end of the temperance demonstrations which take place on Friday evenings. It is hoped that an interest in such matters may be awakened in the audience (usually numbering ten or twelve hundred, or during the winter more than this), which assembles at these demonstrations. It is an audience less of artisans than of labourers and costermongers, among whom the demand for cientific teaching must be created as well as supplied. If once it can be shown that such addresses are appreciated, we have good hope of efficient help in carrying them on, but we should be grateful for offers of help in the pioneer course. Dr. W. B. Carpenter, Dr. Richardson, and one or two others have given conditional promises, but we have not yet sufficient names for a long enough series to try the experiment fairly. To simplify and popularise science to the utmost, without lowering it, is not a task which can be performed by those who have no qualification except goodwill, and as, unfortunately, the Victoria Hall is not yet self-supporting, the comittee cannot offer anything like adequate remuneration for the services of competent and therefore busy men. They would gladly be responsible for the expense of providing lime-light, or hiring apparatus for experiments, but beyond this they must appeal to the public spirit and generosity of scientific men. Communications may be addressed to the Honorary Secretary, Royal Victoria Coffee Hall, Waterloo Road, S.E., or to Miss C. A. Martineau, Walsham le Willows, Bury St. Edmunds. ONE OF THE COMMITTEE Spelling Reform IN your note last week on the United States Spelling Reform Report, there is a slight misapprehension. It is said that the result of adopting a phonetic spelling will be the break-up of the English language. This is quite erroneous. Phonetic spelling simply represents pronunciation, and if the phonetic spelling of London English differs from that of Colonial English it can only be Lecause the pronunciations are different; that is, because the language has already broken up. On the other hand, if the pronunciations are the same, the spellings will be the same, and I fail to see how an identical spelling in London and Australia can bring about a disruption. In the present state of Biblical criticism, I rather wonder that the tower of Babel should be appealed to as evidence of Hebrew thought; but if the Hebrews were really so impressed with the confusion of tongues, and if phonetic spelling is really so conducive to that confusion, then let me ask: Why did the Massorites, with that story before their eyes, go and make the originally phonetic Hebrew alphabet more phonetic still by adding the finest set of vowels that has ever been used? Why, except that they knew, as Prof. Sayce and Dr. Tylor know, and the late Charles Darwin knew, that phonetic spelling is the only thing that preserves language and its history from utter decay. JOHN FENTON Spelling Reform Association, 8, John Street, Adelphi, W.C., August 14 Possible Sound Organs in Sphingid Pupæ IN recently characterising the pupa of Sphinx catalpa, Boisd., for my report as entomologist to the Department of Agriculture, I was struck with the occurrence on the anterior border of each of the larger movable abdominal joints (viz., abdominal joints 5, 6, and 7) of a peculiar elongate concavity, a structure not mentioned by Westwood, Burmeister, Kirby and Spence, Girard, Clemens, Harris, Graber, or any modern author whom I have been able to consult. There is an approach to it in the pupa of Ceratomia amyntor, and it occurs in that of Sphinx harrisii in similar position and form as in S. catalpa. In Macrosila 5maculata it is somewhat above the spiracles, and that on the fifth abdominal joint has a second larger ridge running around it posteriorly. It does not occur in any of the species of the genera Sesia, Thyreus, Darapsa, Deilephila, Philampelus, and Smerinthus in my collection. It has no internal connection with the respiratory or circulatory systems, and its function is probably sound-producing by friction with the posterior margin of the preceding joint. This organ may, in fact, throw some light on the method by which the noise is produced which the pupa of Unfortunately, I have no pupa Sphinx atropos is capable of. of that species for examination. I shall be glad to learn from any of your Lepidopterological readers if they are familiar with this structure on any other pupæ or know of any record of it. C. V. RILEY Washington, D.C., U.S. A. Meteorology of the Antarctic Region IT is well known that on the Antarctic lands perpetual snow descends much lower than in corresponding latitudes of the northern hemisphere. The chief cause of this is, no doubt, the difference of climate due to the preponderance of land in the northern hemisphere and of water in the southern. But there is another cause, of sensible magnitude, which I have not seen mentioned. In high southern latitudes the barometer stands permanently nearly an inch lower than in corresponding northern latitudes, and this must cause a permanently lower temperature in the Antarctic regions. That is to say, a depression of an inch in the barometer corresponds to about 1000 feet of mountain ascent; and any station in the Antarctic region must therefore be as much colder than a corresponding one in the Arctic region, as if the Antarctic station stood 1000 feet higher above the sea-level than the Arctic one. The cause of the barometric depression in the Antarctic region is probably the centrifugal force of the west winds, cr "countertrades," which, as Maury remrrks, surround the South Pole with "an everlasting cyclone on a great scale." JOSEPH JOHN MURPHY Old Forge, Dunmurry, Co. Antrim, August 8 RECTOR (whose appeal for help in protecting a granite boulder in his country parish we inserted in No. 663) requests us to acknowledge with many thanks the following contributions:Saxo, 2s. 6d.; William S. Layman, 2s. 6d. ; J. W. A., 5§. SUN-SPOTS AND MARKREE RAINFALL Y aid of R. Wolf's series,1 I have been endeavouring, if BY possible, to trace the effect of the different state of the sun's surface, as shown by the extent of its spots, on our climate. I distributed the annual rainfall, registered here 1833-1863, into ten classes, according to the corresponding values of "the relative numbers r, as exhibited in Table I. These relative numbers have been determined by Prof. Wolf from a discussion of the registered number of spots and groups of spots on the sun, and are supposed to be proportional to the area covered by spots on the sun's surface. The mean rainfall M, the average of the thirty-one years, is 37 254 inches. o is the rainfall regis 1 "En désignant par g le nombre des groupes de taches nus un jour quel conque sur le soleil, une tache isolée comptant pour un groupe; parle nombre des taches contenue dans tous les groupes, nombre que j'estime approximativement proportionel à la surface tachetée; et par & un coefficient dépendant de l'observation et de son instrument, et déduit d'observations correspondantes, en supposant ce coefficient égal à l'unité pour mai et pour le grossissement 64 d'un Fraunhofer de 4 pieds, je pose: r=¿ (f+108), et je nommer le nombre relatif de ce jour. La moyenne de tous les nombres relatifs appartenant à la même année donne le nombre relatif de l'année." R. Wolf, Mémoire sur la Péric de commune à la Fréquence des Taches Salaires et à la Variation de la Déclinaison Magnetique (Memoirs of the Royal Astronomical Society, vol. xlii., 1877, Part vi). are exhibited in Table I., the last column of which exhibits the remaining errors, v, i.e. the difference between the registered rainfall, o, and the calculated, CM-10x-yr, after that the quantities r and y had been obtained from the equations of condition by solving them by aid of the method of least squares. It will be remarked that vis far smaller than o M in Table I., the average of several years, but the comparison from year to year, o-C as exhibited in Table II., shows but a small decrease in the differences. The result is inches. C = 34 435 +0'04785 r = 37 254 + 0·04785 (r — 58′91). ... ... 56.2 90'3 94'8 777 610 45'4 ... ... ... ... ... ... 40 25 45'72 35 17 34'77 29.36 27.87 35°14 34'34 41'65 43'74 46°52 40°23 34'97 ... +3712 +0°31 -0'08 -0°13 +3.00 +8.47 -2'08 - 2:48 -7.89 -9'38 - 2'11 - 2.91 +4'40 +6'49 +9:27 + 2.98 - 2 28 ... ... o-C. inches. +9.60 + I'42 +125 - 8.41 -0'73 -173 +4'10 -- 1.92 -137 +2'79 - I'II -0'67 - 5'44 - 0'40 +4'77 +8.36 - 1'64 1861 1862 1863 It should be remarked that the receiver of the guage is placed on the top of the library, 16 feet above the ground and 148 feet above mean sea-level. I have placed another guage 6 inches above the ground and 110 feet above the sea, as levelled from bench-mark on observatory wall, and have taken precautions against evaporation from this guage. By comparing the results from the two guages during the last five years, I find that the rainfall registered by aid of the upper guage must be multiplied by 12426 in order to indicate the rainfall at 11c feet above sea. The formula properly reduced is therefore— THE NEW REPTILE HOUSE AT THE ZOOLOGICAL SCIETY'S GARDENS THE present Reptile House in the Zoological Society's Gardens adjoining the Lecture Room, is an old wooden building, which in the early days of the Society was used for lions and tigers, and is now in a very bad state of repair. Besides this it is much too small for the present collection of reptiles. The cages which it contains are always over full, while the tortoises are necessarily lodged in a separate house, and the crocodiles are kept in a building properly destined to contain sloths anʼl marsupials. Moreover, most of the compartments in the present Reptile House are accessible only from the front, which renders it inconvenient, not to say dangerous, to open them in the day-time, when the house is filled with sightseers. Under these circumstances, the Council of the Society have determined to construct an entirely new building for the better accommodation of the reptiles at the southern corner of the Gardens, and having obtained the necessary permission of H. M. First Commissioner of Works, will commence operations immediately. The new Reptile House will be 120 feet long by 60 feet in breadth, with a large porch and double entrance at the front, and keepers' and workers' rooms in the rear. The building will be of brick with corse-hill stone dressings, the roof of iron, slated on the north slope, and provided with ample skylights on the south slope. The house will face due south. It will be fitted with fixed cages for the rep iles on the north, east, and west, leaving the south side (which will be nearly entirely of glass), available for movable cases (such as are now in use in the Insect House), for the smaller and more delicate objects. There will be a large oval pond for crocodiles in the centre of the building, and two smaller circular ponds on each side of it for other aquatic reptiles. The fixed cages, which will be from thirty to forty in number, will be fronted with plate-glass, and the only means of access to them will be from the keeper's passage in the rear, so that there will be no possibility of the animals escaping into the space occupied by the public. The new Reptile House, will, it is expected, be completed and roofed in before Christmas, and as the hotwater apparatus will be finished by the same date, it will be possible to dry it thoroughly during the winter, so that the reptiles may be moved into their new quarters early in the ensuing summer. The designs for the new building have been drawn by Mr. C. B. Trollope, and the contract for its erection has been undertaken by Messrs. Hannen and Holland. The Society's collection of reptiles consists at present of 57 tortoises. 10 crocodiles, 95 lizards, and 83 snakes. Of the last-mentioned, 10 are large pythons and boas, and 14 belong to venomous species. Besides the reptiles there are 56 Batrachians living in the Gardens, which for the present at least, will be kept along with the reptiles. There is, therefore, no fear of the new Reptile House lacking inhabitants, when ready to receive them next year. DIFFICULT CASES OF MIMICRY I SEE a notice regarding mimicry and simulation, by Mr. A. R. Wallace, in NATURE, vol. xxvi. p. 86, and beg to forward the case of a caterpillar mimicking a shrew, as a peculiar instance of this curious law. Here we see the insect unconsciously simulating the very animal that most likely feels on itself, or at least an insectivorous mammal. Passing through a dense forest near a path, I suddenly came on the caterpillar, at about five feet from the ground, on a stout creeper, and of course mistook it for a shrew. Its remaining, and not running off, induced me to look closer, when I saw the green markings, and at once secured the prize, and, after making a sketch or two, put it in my "hatching" cage; unfortunately, I could not find what it fed on, and after spinning a pale greenish cocoon, it died. The natives did not seem to know it. When moving along, it does so as other caterpillars, as seen in the outline 1, of which 2 is plan of the head. If suddenly disturbed, it at once strikes the peculiar pose, as seen in the sketches, and retains it for some time. The general colour is a neutral to brown-grey, beautifully marked, and which I have not attempted to imitate; the general appearance is dark, except where the greenishyellow spots occur. It is the first case I know where a caterpillar mimics a vertebrate animal. The cases are almost innumerable out here, where insects mimic each other and similar or different kinds, or leaves, seeds, flowers, sticks, pieces of grass or clay, &c., &c.; but we see it also in many other cases, not always protective, though invaluable to the animal or the insect. The tiger has one call, when hunting, so like the loud whistle of the Samber (deer) that only an expert and old resident can tell the difference. The deer, if within range, run to it, and I have myself shot a Samber at twenty yards that dashed up on my whistling loudly, with a leaf; unfortunately, native shikaries are only too expert at this. Again, the eye and nose lumps of a crocodile are so like lumps of foam that I have often drifted past close to one in my Rob Roy, and only found it out by the lump of foam quietly and suddenly sinking below the surface of the muddy water. In the case of the tiger the simulation was by sound, to enable it to get food; in that of the crocodile the same end is gained by simulation of appearance, enabling the animal to drift close to prey without alarming it. Asam, June 25 S. E. PEAL THE WASHBURN CHRONOGRAPH THE article on the Brussels Chronograph (NATURE, vol. xxvi. p. 107) induces me to send a brief description of the chronograph of this observatory, which may be taken as representing the form usually adopted by the best American makers, Alvan Clark and Sons, Fauth and Co., Stackpole and Brothers, &c. The accompanying engraving gives a good general idea of it. The scale may be obtained by remembering that the iron base plate is 21 inches by 11 inches. The barrel is 14 inches long by 7 inches in diameter. The paper used is 23 inches by 13 inches which provides for a lap at the line of junction. There is room for the observations of two hours and forty minutes. The weight employed is fifteen pounds, and usually a double pulley is used to diminish the fall. The chronograph can be wound while it is going, with |