of glaciers with dark frowning and flat-topped cliffs, here and there reaching to a height of 1200 feet. It was after passing Barents' Hook that new ground was actually broken, and the exploration was continued westwards until Mr. Smith succeeded in rounding the western headland. The farthest point actually reached by the Eira was in N. lat. 82° 20', E. long. 45°, and thence the land could be seen trending away to the north-west. During the voyage a meteorological record was kept, photographs taken, and various collections made, chiefly of botanical and geological specimens. THE January number of Petermann's Mittheilungen contains an account of a journey from Dufilé to Lur, on the west shore of Lake Mwutan-Nzige, by Dr. Emin Bey, in the last months of 1879. Herr Clemens Denhardt brings together much valuable information on the East African region between Mombasa and the Victoria Nyanza, with special reference to the trade-routes, accompanied by an excellent map. An article of special scientific interest is contributed by Dr. H. Hoffmann on the Comparative Phænology of Central Europe. In a series of tables and in a map the average time of bloom is shown for a very large number of places, with reference to Giessen as a standard. There is a very interesting account by Baron Nordenskjöld of his visit to Behring Island, followed by some critical remarks on the vegetative region of the Serra da Estrella, by Dr. O. Drude. Bulletin, No. 5, 1879, of the American Geographical Society contains a paper by General R. E. Colston on "Life in the Egyptian Deserts," and an amusing lecture by Lord Dunraven on "Moose and Cariboo Hunting." THE French station of the African Association has been established by M. Savorgnan de Brazza at Nghimi, on the route from Machogo to Levumba, in the region of the sources of the Ogové, in 1° 30' S., and about 11° E. from Paris. THE publication in which the results of the determination of the South American longitudes by electricity have been tabulated by American observers has just arrived in Paris. All the positions determined by M. Mouchez on the Brazilian coast have proved correct within a difference of 1 second of time. These determinations were taken by Admiral Mouchez when a subordinate officer in the French service twenty years ago, by lunar distances, occultations, and eclipses. THE author of the summary of Geographical Discovery in Whitaker's Almanac writes to us in reference to the notice on p. 232, that it is not stated that Mr. Leigh Sr. ith's voyage is "the most remarkable geographical event of the year,' to the depreciation of Mr. Thomson's African journey; "but that, in spite of the success of the latter, Mr. Smith's voyage would probably be considered by many as the most remarkable geographical event of 1880." We doubt if "many" would hold such an opinion, merely for the reason assigned in the Almanac. "May I be allowed to point out,' he adds, "that the word 'research' means careful search or investigation? and that mere searching for the North Pole is not the sole object of Arctic voyages?" We are glad the writer is of this opinion, though we doubt if Mr. Leigh Smith's voyage has much bearing on Polar "research." CHESAPEAKE ZOOLOGICAL LABORATORY A REPORT of the third year's work at the Chesapeake Zoo logical Laboratory of the Johns Hopkins University has been addressed to the President of the University by Mr. W. K. Brooks, Director of the Laboratory. An advance copy of this has been sent us, from which we make some valuable extracts. The laboratory was opened at Beaufort, North Carolina, on April 23, 1880, and closed on September 30, after a session of twenty-three weeks. It was supplied with working accommo dations for six investigators, and the facilities which it afforded were used by the following six persons :- -W. K. Brooks, Ph.D., Director; K. Mitsukuri, Ph.B., Fellow in Biology; E. B. Wilson, Ph. B., Fellow in Biology; F. W. King, A.M., Professor of Natural Science, Wisconsin State Normal School; H. C. Evarts, M.D., Academy of Natural Sciences, Philadelphia; H. F. Osborne, Ph.D., Fellow of the College of New Jersey. Beaufort was selected for the third season's work because it is the nearest accessible town south of Baltimore which is favourably situated for zoological study. The scientific advantages of Beaufort are very great; the most important is the great difference between its fauna and that of the northern Atlantic coast. "The configuration of our coastline," the Report goes on, "is such that Cape Hatteras, the most projecting point south of New York, deflects the warm water of the Gulf Stream away from the coast, and thus forms an abrupt barrier between a cold northern coast and a warm southern one. The fauna north of this barrier passes gradually into that of southern New England, while the fauna south of the barrier passes without any abrupt change into that of Florida, but the northern fauna is sharply separated by Cape Hatteras from the southern. As the laboratory of the U.S. Fish Commission and Mr. Agassiz's laboratory at Newport afford opportunities for work upon the northern fauna, it seemed best for us to select a point south of Cape Hatteras in order to study the southern fauna with the same advantages, and as Beaufort is the only town near the Cape which can be reached without difficulty, it was chosen as the best place for the laboratory. The situation of this town is exceptionally favourable for zoological work, for the surrounding waters present such a diversity of conditions that the fauna is unusually rich and varied." After describing in detail the special characteristics of the locality Mr. Brooks goes on to say: "The zoological resources of Beaufort have not escaped the attention of American naturalists, and there are few places upon our coast, outside of New England, where more zoological work has been done. In 1860 Drs. Stimpson and Gill spent a season in dredging and collecting in the vicinity of Beaufort, Cape Lookout, and Cape Hatteras, and an account of their work was published in the American Journal of Science. Dr. Coues, who was stationed at Fort Macon during the war, occupied himself for two years in collecting the animals which are found here, and he published a series of papers on the Natural History of Fort Macon and Vicinity' in the Proceedings of the Academy of Natural Sciences of Philadelphia. These papers, which were continued by Dr. Yarrow, contain copious and valuable notes on the habits and distribution of the animals which were observed, and we found them a great help to us. These two naturalists found 480 species of animals in the vicinity of Beaufort. Of these 480, 298 are vertebrates, and 182 are invertebrates. the vertebrates 24 are mammals, 133 are birds, 27 are reptiles, 6 batrachians, 97 fishes, and 11 selachians. Of the invertebrates 147 are mollusks, 21 are crustaceans. The list of vertebrates is very nearly exhaustive, and we made no additions to it; but the list of invertebrates is obviously very imperfect, and although we made no attempt to tabulate the species which we observed, there would be no difficulty in enlarging the list twenty or thirty fold. 66 Of Among other naturalists who have spent more or less time at Beaufort I may mention Prof. L. Agassiz, Prof. E. S. Morse, Dr. A. S. Packard, Prof. Webster, and Prof. D. S. Jordan. Prof. Morse procured most of the material for his well-known paper on the Systematic Position of the Brachiopoda on the Sand-bars in Beaufort Inlet. "I will now attempt to give a very short statement of some of the leading points in our own summer's work. Much of our time was spent in studying the development of the Crustacea, since this is one of the most important fields for original work upon our southern coast. The supply of material is almost inexhaustible, and would employ a number of students for many years. The life-history of the Crustacea is of great interest in itself, and the recent species are so numerous and diversified that there is no group of animals better adapted for studying the general laws of embryonic development in their relation to the evolution of the group. These considerations have led us to devote especial attention to this group during this and the preceding seasons. One of the published results of the first season's work was an illustrated account of the metamorphosis of Squilla, a representative of a somewhat aberrant group of Crustacea. During the second season a member of our party, Prof. Birge, made a very thorough study of the development of Panopeus, one of our crabs, and the account of his observations, with drawings, was ready for publication several months ago. At Beaufort we spent most of our time upon this subject, and figured more than 800 points in the development of various Crustacea. specimens of one genus at Fort Wool, and the same genusLucifer-in great abundance at Beaufort, associated with another genus which is also new to North America. As nothing whatever was known of the development of Lucifer, we made every effort to obtain the eggs and young, and after four months of almost fruitless labour we finally succeeded in finding all the stages of the metamorphosis, and figured them in a complete series of ninety-nine drawings. We also obtained a somewhat less complete series of figures of stages in the life history of the second Sergestid. Our only motive in this work was the desire to fill a gap in our knowledge of crustacean development by supplying the life-history of a very interesting group of animals, but the result was found to have a very unexpected value, since it contributes to the discussion of a number of problems in general embryology and morphology, and is the most significant crustacean life history which has ever been studied. "The following are some of the more important points :The egg undergoes total regular segmentation. There is no food-yolk, and cleavage goes quite through the egg. There is a true segmentation cavity. Segmentation is rhythmical. There is an invaginate gastrula. The larva leaves the egg as a Nauplius, and passes through a protozoea stage and a schizopod stage. The fifth thoracic segments and appendages are entirely wanting at all stages of development. "Another interesting group which was studied is the Porcellanidæ ; the least specialised of the true crabs. The adults of our American species are almost restricted to our southern waters, although the swimming larvæ are carried north by the Gulf Stream. Within the last two years two northern naturalists have studied these floating embryos upon the south coast of New England, but as they were working upon stragglers so far from home, their accounts are incomplete and somewhat contradictory. Our advantages at Beaufort enabled us to contribute towards the solution of this confused subject by raising one species of Porcellana from the egg. We also raised six other species of crabs from the egg, and made drawings of the more important stages of development. One of the species which was thus studied is the edible crab. Its metamorphosis has never been figured, and although it presents no unusual features, its economic importance gives value to exact knowledge of its life history. Mr. Wilson also studied the development of one s ecies of Pycnogonida, a group of very peculiar Arthropods distantly related to the spiders. As he has paid especial attention to the systematic study of this group, and is now engaged in describing the Pycnogonids collected in the Gulf Stream by Mr. Agassiz, the opportunity to study them alive in the laboratory has been a great advantage to him. "Another important investigation is the study by Mr. Wilson of the embryology of the marine Annelids. Although the representatives of this large group are abundant and widely distributed, little was known of the early stages of their develop ment until he procured the eggs of several species and studied them at Beaufort. This investigation has shown, among other things, that the accepted division of Annelids into two great groups, the Oligochata and Polychata, is not a natural method of classification. The work upon the development of marine Annelids was supplementary to an investigation which Mr. Wilson carried on last spring at Baltimore, and which he will continue this winter, upon the development of land- and freshwater Annelids. "As much time as possible was given this season to the study of the hydroids and jelly-fish of Beaufort. The life history of several of them were investigated, a thorough anatomical study of some of the most important forms was carried on, and nearly two hundred drawings was made. It is almost impossible to complete a study of this kind in a single season, but if one or two more summers can be given to the work, we have every reason to hope for valuable results, for although the North Carolina coast is the home of many species which are only found as stragglers upon our northern coast, and of other species which are not known to occur anywhere else, and of some genera and families which are new to the North American coast, this field has suffered almost total neglect. "Nearly three months of the time of two members of our party, Mitsukuri and Wilson, were given to the study of the habits, anatomy, and development of Renilla, a compound Polyp very much like that which forms the precious coral, but soft and without a stony skeleton. The animals which form the community are so intimately bound together that the community as a whole has a well-marked individuality distinct from that of the separate animals which compose it. The compound individuality of Renilla is quite rudimentary as compared with that of a Siphonophore, and as there is no trace of it in the closely allied Gorgonias, it furnishes an excellent field for studying the incipient stages in the formation of a compound organism by the union and specialisation of a community of independent simple organisms. With this end in view the anatomy of the fullydeveloped community was carefully studied, and the formation of a community was traced by rearing a simple solitary embryo in an aquarium until a perfect community had been developed from it by budding. During the process of development the law of growth by which the characteristics of the compound organism are brought about was very clearly exhibited, and it is fully illustrated by nearly one hundred drawings. "One of the most interesting results of our work is the explanation by Mr. Wilson of the origin of the metamorphosis of the larva of Phoronis, a small Gephyrean worm which lives in a tube. Several of the most noted embryologists of Europe have studied the development of Phoronis, and our knowledge of its life history is due to their combined labours. Last summer Mr. Wilson reviewed the subject, and added some important points, and during the present season he has shown by the comparison of a great number of allied forms that the very peculiar meta. morphosis admits of an extremely simple explanation. The adult is sedentary and confined to its sand tube, while the larva is a swimming animal totally different in structure. The change from the larva to the adult is very rapid and violent. It occupies only a few minutes, and during the change the larva becomes turned wrong side out, so that what was internal is external. Mr. Wilson's comparison shows that Phoronis was originally a free animal, and that the structural peculiarities which fit the adult for sedentary life in a tube are of recent acquisition. The larva has however retained its ancestral adaptation to a swimming life in order to provide for the distribution of the species. There must have been a time, in the evolution of the species, when the adult was imperfectly adapted to a sedentary life, and also imperfectly adapted to a swimming life; and if the development of the individual were a perfect recapitulation of all the stages in the evolution of the species, we should have, between the swimming larva and the sedentary adult, a stage of development during which the adaptation is not quite perfect for either mode of life. It is clearly an advantage for the animal to pass through this stage as quickly as possible, or to escape it altogether. The peculiar metamorphosis enables the larva to remain perfectly adapted to a locomotor life until the occurrence of the sudden change which fits it for life in a tube; and Mr. Wilson has pointed out the manner in which the metamorphosis has been acquired in order to bridge over the period of imperfect specialisation. This explanation is somewhat similar to that which Lubbock has given of the origin of the metamorphosis of insects, and we may hope that the same method of investigation will throw light upon the significance of other remarkable instances of metamorphosis in the invertebrates. "During the summer the following abstracts of some of the more important points in our work have been published in scientific journals: The Development of the Cephalopoda and the Homology of the Cephalopod Foot. By W. K. Brocks. Amer. Journal of Science. The Development of Annelids. By E. B. Wilson. Amer. Journal of Science. The Rhythmical Nature of Segmentation. By W. K. Brooks, Amer. Journal of Science. The Origin of the Metamorphosis of Actinotrocha. By E. B. Wilson. Amer. Assoc., Boston Meeting. Notes on the Medusa of Beaufort. By W. K. Brooks. Amer. Assoc., Boston Meeting. Budding in Free Medusa. By W. K. Brooks. Amer. Nat. Development of Marine Polychatous Annelids. By E. B. Wilson. Zoologischer Anzeiger. Embryology and Metamorphosis of Lucifer. By W. K. Brooks. Zoologischer Anzeiger. The Early Stages of Renilla. By E. B. Wilson. Amer. Journal of Science. "Other abstracts are now in the press, and others are ready, for publication. "A paper, with four plates, on the 'Early Stages of the Squid,' is also in the press, and will soon be issued in the Memorial Volume of Memoirs of the Boston Society of Natural History." ELASTICITY OF WIRES1 THE experiments described in this paper form a continuation of experiments undertaken in connection with the work of the Committee of the British Association for commencing secular experiments on the elasticity of wires. Long-continued application of stretching force increases to a very great extent the tensile strength of soft iron wire. Thus in experiments described to the British Association in 1879 (see Report of the Committee just referred to), a particular very soft iron wire was shown to have a breaking weight 10 p.c. higher if the weight necessary to break it is applied half a pound at a time per day, than it has if the breaking weight is applied half a pound at a time at intervals of say two minutes. It was found also that this wire, quickly broken, extends before breaking by as much as 25 p.c. of its original length; whereas if the application of the stress is very slow, the extension is not more than 5 or 6, or perhaps 8 p.c. Further experiments have been undertaken on this subject, and are still in progress. Using a continuous arrangement for applying the stretching weight and employing some very soft iron wire which had been specially prepared, and which was used in former experiments, the greatest weight which could be rapidly put on the wire without breaking it was determined. It was found that with a weight of 41 lbs. gradually applied in 61 minutes the wire stretched by 24'4 p.c. of its original length, and broke 18 minutes after the weight was put on. With the same weight, 41 lbs., applied in 6 minutes, the wire stretched 22'1 p.c. and broke in 24 minutes. With 41 lbs., however, applied in 7 minutes, the wire stretched 18 p.c., and did not break. This weight, therefore, appeared to be just as much as the wire would bear with this method of applying the weight. Accordingly it was applied to a great number of wires for different lengths of time for the purpose of hardening them, and arrangements have been made for keeping a number of wires for very long times with this stretching force applied to them. The amount of extension produced by the application of the hardening stress was observed in each case. After the hardening stress had been applied for a certain time the additional weight necessary to break the wire was determined, and also the additional elongation before breaking, which was in all cases almost insensible. The wires seemed permanently set in about forty minutes from the time when the hardening stress was applied. They did not alter in length till just before they broke, when they generally stretched 1 or 2 millimetres on a length of about 1,800 mm. The following table shows some of the results out of a great many that have already been obtained. Curves have also been obtained and were exhibited to the Section showing the extension with gradually applied weights both of a number of wires and of the different parts of the same wire; also curves showing the extension at different intervals of time from the beginning of an experiment in which the wire is running down under a weight sufficient to break it finally. The author acknowledged the great assistance that he had received from Mr. A. C. Crawford and other students the in Physical Laboratory of the University of Glasgow. Similar experiments are in progress on wires of copper and tin, and it is intended to test gold wire very soon, as it will probably give interesting results, and results very different from those given by soft iron wires. 1 Strength and Elasticity of Soft Iron Wires. Abstract of a Paper read at the British Association, by J. T. Bottomley, M.A., F.R.S.E. SPECTROSCOPIC NOTES, 1879-80. DOUBLE Reversal of Lines in Chromosphere Spectrum.—The magnesium lines of the b group, and the two D-lines of sodium have been seen several times (first on June 5, 1880) doublyreversed in the spectrum at the base of a prominence. A bright line first appears in the centre of the widened dark lines; then this bright line grows wider and hazy at the edge, and a thin dark line appears in its centre, as shown in the figure. The phenomenon lasts usually from ten minutes to an hour. It is evidently the exact correlative of the double reversal of the bright sodium lines, observable in the flame of a Bunsen burner or alcohol lamp under certain circumstances when the quantity and temperature of the sodium vapour in the flame are greatly increased. The H-lines in the Chromosphere and Sun-spot Spectra.-In 1872 I found the H- and K-lines to be reversed in the spectra of prominences and sun-spots, as observed at Sherman, 8000 feet above the sea. Until recently I have not been able to verify the observation, except for a moment during the eclipse of 1878. During the past summer, however, I have succeeded in seeing them again, and with suitable precautions as to shadeglass, adjustment of slit to true focal plane for these special rays, and exclusion of extraneous light, I have no further difficulty with the observation. The spectroscope employed has collimator and view-telescope each of 1 inches aperture, and about 13 inches focal length, and a speculum-metal Rutherfurd grating with 17,300 lines to the inch. A shade of cobaltblue glass greatly aids the observation. The solar image is 1 inches in diameter. In the spectrum of the chromosphere, H and K are both always reversed. I have never failed to see them both when circumstances were such that h, the nearest of the hydrogen lines, could be seen. Furthermore, H, in the chromosphere spectrum, is always double: that is, a fine bright line always accompanies the principal line, about one division of Ångström's scale below. The principal line seems to be exactly central in the wide dark shade, the other is well within the nebulosity. K on the other hand shows no signs of duplicity. In the spectrum of a sun-spot H and K are also, both of them, generally, though not always, reversed; and the reversal is not confined to the spot, but covers often an area many times larger in its neighbourhood. In the spot spectrum, however, H has never yet been seen double. The companion line of H is therefore probably due to some other substance than that which produces H and K; a substance prominent in the chromosphere, but not specially so in the neighbourhood of spots. In view of the recent observations of Vogel, Draper, and Huggins, it is natural to think that hydrogen is probably the element concerned. If so, it may be expected that H will be found doubled in the spectrum of a spot which reverses the hydrogen line h. I have not yet been able to test it in this way, as h is rarely seen reversed, though C and F occur pretty frequently. [Note. An observation made since my paper was written leads me to modify this opinion, that the companion of H is due to hydrogen, and satisfies me that in all probability both H and K must themselves be hydrogen-lines. At II A. M. on October 7, a bright horn appeared on the S.E. limb of the sun. When first seen it was about 3' or 4' in elevation, but it rapidly stretched up, and before noon reached a measured altitude of over 13' (350,000 miles +) above the sun's limb. It faded away and disappeared about 12.30. It was brightest about 11.30 with an altitude of about 8' and at this time both H and K were distinctly, and for them, brilliantly reversed in it clear to the summit. H was not double in it to any notable elevation, though the companion of H was visible at the base of the prominence. The H- and K-lines also showed evidence of violent cyclonic action, just as C did. h was only faintly visible in the prominence; F and the line near G were of course strong. But no other lines, either of sodium, magnesium, or anything else, could be traced more than a very few seconds of arc above the sun's limb. I am not able to say how long the H-lines continued visible, or to what elevation they extended afterwards, as I returned to the C-line to watch the termination of the eruption. If I remember rightly, this eruption reached a higher elevation than any before observed. There was (and is to-day) nothing on the sun's limb visible with the telescope which would account for it.-Princeton, October 8.] Examination of Lines in the Solar Spectrum which are given in the Maps as common to Two or more Substances.—-For this purpose a spectroscope of high dispersion has been constructed by combining the grating mentioned above, which has about 4 square inches of ruled surface, with a collimator and observing telescope each of 3 inches aperture and about 42 inches focal length, using magnifying powers ranging from 50 to 200. The apparatus is arranged upon a wooden frame-work, and when in use is strapped to the tube of the 12-feet equatorial of our observatory, so that it is kept by the driving-clock directed to the sun. An image of the sun is formed on the slit by an achromatic objectglass of 3 inches aperture, in order to increase the light and to avoid the widening of the lines due to the sun's rotation. large prism of about 20° angle was sometimes placed in front of this object-glass (between it and the sun) to separate the colours before reaching the slit; and in examining the darker portions of the spectrum a concave cylindrical lens was sometimes used next the eye, like a shade glass, to reduce the apparent width of the spectrum and thus increase its brightness. A The grating is an admirable one, on the whole the best I have ever seen. But I have been greatly surprised at its excessive sensitiveness to distortion by pressure or inequalities of temperature. Although the plate is fully of an inch thick, and only 3 inches square, an abnormal pressure of less than a single ounce at one corner will materially modify its behaviour, and a quarter of a pound destroys the definition entirely. In fact the plate is not naturally exactly flat, and to get its best performance it is necessary to crowd a little wedge gently under one corner. When it is in good humour and condition, however, the performance is admirable; one could wish for nothing better, unless for a little more light in the violet portions of the spectrum. With this instrument I have examined the 70 lines given on Ångström's map as common to two or more substances. Of the 70 lines, 56 are distinctly double or triple; 7 appear to be single; and as to the remaining 7, I am uncertain; in most cases, because I was unable to identify the lines satisfactorily on account of their falling upon spaces thickly covered with groups of fine lines, none of which are specially prominent. As a general rule the double lines are pretty close, the distance being less than that of the components of the 1474 line. Generally also the components are unequal in width or darkness, or both, though in perhaps a quarter of the cases they are alike in appearance. The doubtful lines are the following, designated by their wave length on Ångström's map: 5489'2, 54250, 5396 1, 5265 8, 4271'5, 4253'9 and 4226 8. I strongly suspect 53961 and 52658 (which present no difficulty in identification) of being double, but could never fairly split either of them, and therefore leave them among the doubtfuls. Those which show no signs of doubling, so far as could be seen, were: 6121*2, 6064'5, 5019'4, 4585'3, 4578′3, 4249'8, and 4237'5. In respect to the lines 5019'4, 4585'3 and 42375 it is quite possible there may be some mistake as to the coincidence, since in his tables Thalen gives neither of them as due to iron. An accidental strengthening of the dotted line, which, on the map, leads up from the symbol of the element concerned, through the iron spectrum, would account for the matter, by making the line appear on the map as belonging to iron also. As the facts stand, therefore, it is obvious that arguments which have been based upon the coincidence of lines in the spectra of different elements lose much of their force; it appears likely that the coincidences are in all cases only near approximations. At the same time this is certainly not yet demonstrated. The complete investigation of the matter requires that the bright line spectra of the metals in question should be confronted with each other and with the solar spectrum under enormous dispersive power, in order that we may be able to determine which of the components of each double line belongs to one, and which to the other element. If in this research it should be found that both of the components of a double line were represented in the spectra of two different metals, and the suspicion of impurity were excluded, we should then indeed have a most powerful argument in favour of some identity of material or architecture in the molecules of the two substances involved. Distortion of Solar Prominences by a Diffraction Spectroscope.Generally, in such an instrument, the forms seen through the opened slit are either disproportionately extended, or compressed along the line of dispersion. The reason is this: if the slit be illuminated by monochromatic light, the image of the slit, formed on each side of the simple reflected image in the focus of the view-telescope (which is supposed to have the same focal length as the collimator), will have the same width as the slit itself only in one special case, not usually realised with a reflecting grating. If the angle, between the normal to the grating and the view-telescope, is less than that between the normal and the collimator, the slit-image will be narrower than the slit, and a prominence seen through it will be compressed in the plane of dispersion. If the relation of the angles be reversed, then of course the distortion will also be reversed, and we shall have extension instead of compression. The mathematical theory is very simple. Suppose the collimator and telescope to be fixed at a constant angle, as in the now usual arrangement. Let angle between telescope and collimator = a. Angle between telescope and normal to grating = 7. Then, by principles of spectrum formation, we have 入= S n {sin x}, which reduces to, dr = (cos asin a tan т) dк. Distortion can only disappear in cases when this coefficient of de reduces to unity. Special cases- 1. If there is no distortion-but also no dispersion: it is the case of simple reflection. 2. If x=0, the grating being kept normal to the collimator, then dr seс а dк. 3. If T=0, the grating being kept normal to the telescope (which in this case must be movable), then dr = cos a ďê. 4. If a=90°, dт=tan т dк. 5. If a=0, dт=dk, and there is no distortion. This is possible only by using the same tube and object-glass both for collimator and view-telescope, the grating being slightly inclined at right angles to the plane of dispersion. The principal difficulty in this form of instrument lies in the diffuse light reflected by the surfaces of the object-glass. It is hoped that this may be nearly obviated by a special construction of the lens which will throw the reflected light outside of the eyepiece. An instrument on this plan is being made for Prof. Brackett by the Clarks, for use in the physical laboratory at Princeton, and is now nearly completed. DR. J. E. HARRIS (D.Sc. Lond.) has been appointed to the vacant Professorship of Natural Philosophy at Trinity College, London. FROM the new Calendar of the University College of Wales we learn that the present number of students is fifty-seven. We see there are classes for most of the branches of science, only unfortunately they are all taught by one professor, which, to say the least, must be rather hard on him. We hope the college will soon be able to have separate teachers, at any rate for the physical and biological sciences. THE new University Library at Halle has just been opened. It is built entirely on the French system, and special precautions have been taken with regard to fire. It now numbers some 200,000 volumes, but there is room for half a million. The cost of the building amounts to 400,000 marks (20,000%.). SCIENTIFIC SERIALS THE American Naturalist for December, 1880, contains :D. Cope, on the extinct cats of America. -F. V. Hayden, Twin lakes and Teocalli Mountain, Central Colorado, with remarks on the glacial phenomena of that region.-C. E. Bessey, sketch of the progress of botany in the United States in the year 1879.C. S. Minot, sketch of comparative embryology, No. 5; on the general principle of development.-The Editor's Table.-Permanent exhibition of Philadelphia.-Recent literature.-A new edition of Packard's "Zoology" is announced.-General Notes. Scientific news. Proceedings of scientific societies. Revue des Sciences Naturelles, December, 1880, contains: Herborisations of Strobelberger about Montpellier in 1620, translated, with notes, by M. Kieffer (a complete exposé of the extraordinary plagiarism of Strobelberger, who copied his work on the plants of Montpellier almost verbatim from the work of Lobel).-M. Doumet-Adanson, on an immense Calamary taken near Cette, January, 1880 (Ommastrephes sagittata). This specimen was nearly six feet in length, from the end of the body to the tops of the arms.-M. S. Jourdain, on the late development of scales in the eels.-E. Dubrueil, catalogue of testaceous mollusca collected from the French shores of the Mediterranean. -M. Reitsch, an analysis of Falkenberg's researches on the fecondation and alternation of generation in Cutleria.-F. Fontannes, on the stratigraphical position of the Pliocene group of Saint Aries, in the Western Bas-Dauphiné, and particularly in the environs of Hauterives (Drôme).-Scientific Reports and Bulletin. Gegenbaur's morphologisches Jahrbuch, Band 6, Heft 4.—Dr. M. v. Davidoff, contribution to the comparative anatomy of the posterior limb masses in fishes, 2nd part (Plates 21, 23); Dr. W. Pfitzner, on the epidermis in the amphibia (Plates 24, 25); J. E. V. Boas, on the conus arteriosus in Butirinus albula and in other Teleostei (Plate 26); Dr. H. Rabl-Rückhard, on the mutual relations between the chorda, hypophysis and the middle ridge of the skull in the embryos of the sharks', &c., brains (with Plates 27, 28); Carl Rabl, on the "pedicle of invagination," &c., in Planorbis (Plate 29); Prof. R. Wiedersheim, on the duplication of the os centrale in the carpus and tarsus of Axolotl (Plate 30); Prof. C. Gegenbaur, critical remarks on polydactylism as atavism; short notices; W. Leche, on the morpology of the pelvic region in the Insectivora. Archives des Sciences Physiques et Naturelles, December 15, 1880.-Tertiary man in Portugal, by M. Choffat,-Monograph of the ancient glaciers and the erratic formation of the middle part of the Rhone valley, by MM. Falsan and Chantre.-Organic dust of the atmosphere, by Dr. Yung.-On the question of lowering of the high waters of the Lake of Constance, by M. Achard. SOCIETIES AND ACADEMIES Royal Society, January 6.-Observations on the Structure of the Immature Ovarian Ovum in the Bird and Rabbit, and on the Mode of Formation of the Discus Proligerus in the Rabbit and of the "Egg-Tubes" in the Dog. By E. A. Schäfer, F.R.S. The first part of the paper is devoted to a minute description of the young ovarian ova of the bird as seen in sections of the ovary of a laying hen. The germinal spot is described as composed of two distinct substances, namely, a homogeneous matrix staining but slightly with logwood and a number of coarse granules imbedded in it, which become darkly stained. The germinal spot may often be seen to be connected with the wall of the germinal vesicle by a network of fine filaments (intranuclear network). Appearances are also described which indicate that two germinal vesicles may be originally present in one ovum (? formed by the fusion of two primitive ova), and that one of the two may afterwards disappear. A network of filaments is also described as existing in the yolk, which in some ova shows peculiar condensations of vitelline substance, which simulate nuclei; but the origin and meaning of these are left in doubt. Other appearances, as of systems of striæ, are also mentioned as occurring in larger ovarian ova. With regard to the membranes of the ovum the author differs from Waldeyer and agrees with Balfour in regarding the zona radiata as a product of the protoplasm of the ovum, and not as derived from the cells of the follicular epithelium. The ovarian ovum of the rabbit is next described, and is found to agree in most essential particulars with that of the bird. The zona pellucida is porous, and allows granules of foodmaterial to pass from the epithelium cells of the Graafian follicle directly into the vitellus. But it is chiefly in this epithelium that the interest centres, for the inner layer of cells of the follicular epithelium appears to be formed in the peripheral layer of the vitellus of the ovum itself, making their appearance first of all as mere nuclei (derived in all probability from the nucleus of the ovum), around which part of the protoplasm or vitellus of the ovum becomes segmented off. This description is compared with that which Kuppfer gives of the formation of an inner layer of follicular epithelium from nuclei which make their appearance in the periphery of the vitellus of the ovum of Ascidia canina, and with the observations of Kleinenberg upon the formation of a layer of cells from the periphery of the ovum of Hydra. Finally the gland-like nature of the ovarian tubes in the bitch's ovary is insisted upon in agreement with Pflüger and Waldeyer, and in opposition to the view taken by Foulis. January 13.-"On the Forty-eight Co-ordinates of a Cubic Curve in Space," by William Spottiswoode, President R.S. In a note published in the Report of the British Association for 1878 (Dublin), and in a fuller paper in the Transactions of the London Mathematical Society, 1879 (vol. x. No. 152), I have given the forms of the eighteen, or the twenty-one (as there explained), co-ordinates of a conic in space, corresponding, so far as correspondence subsists, with the six co-ordinates of a straight line in 'space. And in the same papers I have established the identical relations between these co-ordinates, whereby the number of independent quantities is reduced to eight, as it should be. In both cases, viz., the straight line and the cubic, the co-ordinates are to be obtained by eliminating the variables in turn from the two equations representing the line or resulting from the eliminations. the conic, and are, in fact, the coefficients of the equations In the present paper I have followed the same procedure for the case of a cubic curve in space. Such a curve may, as is well known, be regarded as the intersection of two quadric surfaces having a generating line in common; and the result of the elimination of any one of the variables from two quadric equations satisfying this condition is of the third degree. The number of coefficients so arising is 4 X 10 = 40; but I have found that these forty quantities may very conveniently be replaced by forty-eight others, which are henceforward considered as the co-ordinates of the cubic curve in space. The number of identical relations established in the present paper is thirty-four. But it will be observed that the equations are lineo-linear in each of two groups, say the U-co-ordinates and the U'-co-ordinates; and as we are concerned with the ratios only of the coefficients, and not with their absolute values, we are, in fact, concerned only with the ratio of the U-co-ordinates inter se, and the U'-co-ordinates inter se, and not with their absolute values. Hence the number of indepe› dent co-ordinates will be reduced to 48 - 34 − 2 = 12, as it should be. Mathematical Society, January 13.-S. Roberts, F.R.S., president, in the chair.-Miss C. A. Scott and Messrs. J. Parker Smith, O. H. Mitchell, Fellow of John Hopkins University, and T. Craig, U.S. Coast Survey Office, Washington, were elected members. Dr. Hirst, in drawing attention to the loss the Society had sustained by the death of M. Chasles, gave a rapid sketch of that distinguished geometer's career and work; in lightly touching upon his private life he mentioned how gratified M. Chasles had been by the fact that he was not only the first Foreign Member of the Society, but for a long time the only one. The following communications were made:---On an apparently paradoxical relation of the circle, parabola, and hyperbola, by A. J. Ellis, F. R.S.-A proof of the differential equation which is satisfied by the hypergeometric series, by the Rev. T. R. Terry.-On the periodicity of hyperelliptic integrals of the first class, by W. R. W. Robert.-On the tangents drawn from a point to a nodal cubic, by R. A. Roberts.-Sur une propriété du paramètre de la transf rmée canonique des formes cubiques ternaires, by Signor Brioschi (Milan).-Note on a kinematical theorem connected with the rectilinear courses of two vessels sailing uniformly, by C. W. Merrifield, F.R.S.-A partition-problem connecting the angles a triangle with the angles of the successive pedal triangles, y J. W. L. Glaisher, F.R.S. PARIS Academy of Sciences, January 10.-M. Wurtz in the chair.-The following papers were read: On the conditions |