United Kingdom," and "On the Necessity of the Immediate Investigations of the Anthropology of Oceanic Islands."

I. Physiology.—This section was presided over by Prof. Michael Foster, who since 1883 has been Professor of Physiology in Cambridge, and is well known as the author of several text-books on physiology. His address dealt with the events in physiology for the thirteen years that had elapsed since the association met in Montreal. After alluding to certain conspicuous events that had occurred, he said of some of the older problems, such as muscular contraction: “ Progress, if not exciting, has been real; we are some steps measurably nearer an understanding what is the exact nature of the fundamental changes which bring about contraction and what are the relations of those changes to the structure of muscular fiber. In respect to another old problem, too, the beat of the heart, we have continued to creep nearer and nearer to the full light. Problems again, the method of attacking which is of more recent origin, such as the nature of secretion, and the allied problem of the nature of transudation, have engaged attention and brought about that stirring of the waters of controversy which, whatever be its effects in other departments of life, is never in science wholly a waste of time, if indeed it be a waste of time at all, since in matters of science the tribunal to which the combatants of both sides appeal is always sure to give a true judgment in the end." Of physiological chemistry he said: "The old physiological chemistry is passing away; nowhere, perhaps, is the outlook more promising than in this direction, and we may at any time receive the news that the stubborn old fortress of the proteids has succumbed to the new attack." He discussed as a marked feature of the period "the increasing attention given to the study of the lower forms of life, using their simpler structures and more diffuse phenomena to elucidate the more general properties of living matter." The advances made in the study of the internal secretion, the central nervous system, and the workings of the brain were fully rehearsed and discussed.

Among the more important papers read before this section were the following: The Rhythm of Smooth Muscles," by Henry P. Bowditch; "The Innervation of Motor Tissues, with Especial Reference to Nerve Endings in the Sensory Muscle Spindles," by Carl Huber; "The Muscle Spindles in Pathological Conditions," by O. F. Grunbaum; The Ear and the Lateral Line in Fishes," by F. S. Lee; "On the Effect of Frequency of Excitation on the Contractility of Muscle," by W. P. Lombard; "A Dynamometric Study of the Strength of the Several Groups of Muscles and the Relation of Homologous Muscles in Man " and "A Dynamometer for Clinical Use," by J. H. Kellogg: "The Output of the Mammalian Heart examined by a New Method," by G. N. Stewart; "Observations on the Mammalian Heart," by W. T. Porter; "Leber die naechsten Probleme der Haemodynamik," by Karl Huerthle; "The Comparative Physiology of the Cardiac Branches of the Vagus Nerve," by W. H. Gaskell; "On Rhythmic Variations in the Strength of the Contractions of the Mammalian Heart," by Prof. Cushny: "The Physiological Effects of Peptone," by W. H. Thompson; "The Absorption of Serum in the Intestines," by E. Waymouth Reid; "The Function of the Canal of Stilling in the Vitreous Humor" and "Description of some Pieces of Physiological Apparatus," by Anderson Stuart; "On the Phosphorus Metabolism of the Salmon in Fresh Water," by Noel Paton; "Electrostatical Experiments on Nerve simulating the Effects of Electric Rays," by Jacques Loeb; "Gastric Inversion of Cane Sugar

by Hydrochloric Acid," by Graham Lusk; "Study of the Comparative Physiology of the Cells of the Sympathetic Nervous System," by Carl Huber; "On the Micro-Chemistry of Nerve Cells," by J. J. Mackenzie: "Changes in the Ganglion Cells of Cord after Section of Nerve Roots," by Dr. Warrington; "Action of Reagents on Nerve," by A. Waller; "Action of Anaesthetics on Nerve," by F. S. Lloyd; "Action of Anaesthetics on Cardiac Muscle," by Miss Welby; "The Refractory Period of Nerve," by Charles Richet; "On a Cheap Chronograph," by W. P. Lombard; "Demonstration of the Pendulum Chronoscope for Accurate Movements of Time, together with Some Accessory Apparatus" and "The Tricolor Lantern as applied in teaching the Physiology and Psychology of Color Vision," by E. W. Scripture; "Visual Contrast and Flicker Experiments," by Prof. Sherrington; "Microscopic Specimens illustrating the Distribution of Iron in Cells," by A. B. Macallum; "Microscopic Specimens illustrating the Presence of Copper in Cells" and "On the Presence of Copper in Animal Cells," by R. Royce and W. A. Herdman; "On Intestinal Absorption of Hæmoglobin and Ferratin," by F. W. G. Mackay; "On Secretion in Gland Cells" and "The Morphology and Physiology of Gastric Cells," by R. R. Bensley; "Visual Reaction to Intermittent Stimulation," by O. Grunbaum; "Functional Development of the Cerebral Cortex in Different Groups of Animals: The Psychic Development of Young Animals," by Wesley Mills; The Physiology of Instinct," by Lloyd Morgan; The Nature and Physical Basis of Pain," by L. Witmer; "On the Action of Glycerin upon the Growth of the Tubercle Bacillus," by S. M. Copeman; "Inhibition as a Factor in Muscular Coordination," by C. S. Sherrington; "A Movement produced by the Electric Current," by F. Braun.

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On Aug. 24 a joint meeting was held with Section K (botany), at which the " 'Chemistry and Structure of the Cell" was discussed, and in connection with which the following papers were read: "On the Rationale of Chemical Synthesis," by R. Meldola; "On the Existence in Yeast of an Alcohol-Producing Enzyme," by J. R. Green; and "New Views on the Significance of Intracellular Structures and Organs," by A. B. Macallum.

K. Botany.-Prof. H. Marshall Ward, who since 1895 has been Professor of Botany in the University of Cambridge, presided over this section. His address was devoted chiefly to a review of the advances in our knowledge of the fungi. In opening he alluded to the progress made in the various departments of botany, which were tending toward the specialization of this science-a fact now tacitly, but soon to be openly, recognized. Already the establishment of bacteriological laboratories and a huge special literature; of zymotechnical laboratories and courses on the study of yeasts and mold fungi; of agricultural stations, forestry and dairy schools, and so on, were signs of the inexorable results of progress. After referring to the growth of specialism in botanical study and its reward in the form of a wealth of additional discovery, Prof. Ward entered upon a review of the advances in the knowledge of fungi during the last three decades, dealing particularly with the agency of fungi in alcoholic fermentations. Of the destruction of bacteria he said: "There is one connection in which recent observations on enzymes in the plant cell promises to be of importance in explaining the remarkable destructive action of certain rays of the solar light on bacteria. The English observers Downes and Blunt showed long ago that if bacteria in a nutrient liquid are exposed to sunlight they are rapidly killed. Further researches gradually brought out the facts that it is really the light

rays and not high temperatures which exert this bactericidal action. That these matters are of importance in limiting the life of bacteria in our streets and rivers, and that the sun is our most powerful scavenger, has been shown." The speaker emphasized the need of recognizing that bacteriology only touches animal pathology at a few points, and of the public learning that, so far from bacteria being synonymous with disease, the majority of these organisms appeared to be beneficial rather than inimical to man. Cases were cited as pointing to the conviction that a school of bacteriology which had nothing to do with medical questions, but investigated problems raised by the forester, agriculturist, and gardener, the dairyman, brewer, dyer, and tanner, etc., would yet be established in connection with some great botanical center. The speaker then went exhaustively into the discoveries regarding the exact relation of bacteria to the various methods of cheese and butter manufacturers, and pointed out the value of the researches of many well-known scientists in this subject. Prof. Ward next dealt with the action of fungi upon the roots of forest trees, and then explained the nature of researches and the nitrifying organisms found in manure and soils. With respect to these it was shown that there now exists a sketch of the whole of the down grade of the cycle of organic nitrogen in Nature; it only needs supplementing by the history of the fixation of free nitrogen from the atmosphere by leguminous plants and certain soil organisms to complete the sketch. In conclusion, he dealt with wheat rust and the use of manure.

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Among the more important papers read before this section were the following: "On the Mycelium of a Witches' Broom Fungus," by P. Magnus; "Stereum Hirsutum: A Wood-Destroying Fungus," by H. Marshall Ward; "The Nucleus of the Yeast Plant," by H. Wager; "A Disease of the Tomatoes," by W. G. P. Ellis: "The Chimney-shaped Stomata of Holocantha Emeryi: Some Consideration on the Functions of Stomata" and "Distribution of Nebraska Trees," by Charles E. Bessey; "On the Species of Picea in Northeastern America," by D. P. Penhallow; "Contribution to the Life History of Ranunculus," by John M. Coulter; Vegetation of the Region of the Prairie Province," by Roscoe Pound and F. E. Clements; "The Zonal Constitution and Distribution of Plant Formations" and "The Transition Region of the Caryophyllales," by F. E. Clements; "Note on Pleurococcus," by Dorothea F. M. Pertz; "Spermatozoids of Zamia Integrifolia," by H. J. Weber; "Diagrams illustrating the Result of Fifty Years' Experimenting on the Growth of Wheat at Rothamsted, England," by H. E. Armstrong; "Preliminary Account of a New Method of Investigating Stomata," by Francis Darwin; "Notes on Lilæa," by D. H. Campbell; "Lecture on Fossil Plants," by A. C. Seward; "On the Existence of Motile Antherozoids the Dictyotacea," by J. L. Williams; "Insemination in Ferns and "On more than One Plant from the Same Prothallium," by E. J. Lowe; "Results of Some Experiments in Cross Fertilization," by W. Saunders; "On a Hybrid Fern, with Remarks on Hybridity," by J. B. Farmer; "Morphology of the Stele in Vascular Plants" and "The Gametophyte of Botrychium virginianum," by E. C. Jeffrey; "Remarks on Changes in Number of Sporangia in Vascular Plants," by F. O. Bower; "Notes on Fossil Equisetaceæ," by A. C. Seward; "On Streptothrix actinomycotica and Allied Species of Streptothrix," by E. M. Crookshank; “Observations on the Cyanophycea," by II. B. Macallum.

Also the following reports were presented before

the section: "On the Preservation of Plants for Exhibition' and "On the Fertilization of the Phæophyceæ." On Aug. 24, as previously noted, this section met in joint session with Section I.

Popular Features.-On Aug. 19 their Excellencies the Governor General of Canada and the Countess of Aberdeen gave an evening reception to the officers, members, and associates of the association in the legislative building. The first evening lecture, on Canada's Metals," by Prof. W. C. Roberts-Austen, was delivered on Aug. 20. On the evening of Aug. 21 a lecture for the workingmen of Toronto, on "British New Guinea: The Country, its People, and the Problems which the Region offers to Naturalists and Geographers," was given by Dr. H. O. Forbes. Special sermons were preached on Aug. 22 in St. James's Cathedral by Bishop Sullivan; in St. James's Square Presbyterian Church by President Patton, of Princeton University; and in St. Michael's Cathedral by the Rev. P. A. Halpin and the Rev. Father Ryan. The usual devotional service of the association was held in the university on Sunday under the direction of the Rev. Principal Sheraton. The second evening lecture was on "Earthquakes and Volcanoes," and was delivered on Aug. 23 by Prof. John Milne. The usual conversazione was given by the local executive committee in the university building on Aug. 24. On Aug. 25 a dinner was given in honor of Lord Kelvin, Lord Lister, and Sir John Evans in the pavilion of the Horticultural Gardens. Two interesting ceremonies during the week were the convocations of the University of Toronto on Aug. 20, when the honorary degree of LL. D. was conferred on Lord Kelvin, Lord Lister, and Sir John Evans, and that of the University of Trinity College, on Aug. 24, when the honorary degree of D. C. L. was conferred on Sir John Evans, Lord Kelvin, Lord Lister, Sir William Turner, James H. Bryce, and Sir George S. Robertson. The afternoon entertainments included garden parties, several of which were held on each afternoon during the week. In addition to the foregoing, a series of four special excursions -as follow: To Niagara river, Niagara Falls, and return; to Muskoka and return; to Penetanguishene and return; and to Hamilton, Niagara Falls, and return-were arranged for Aug. 21; and subsequent to the meeting the following excursions were provided for: To Toronto, Ottawa, Ottawa river, Montreal, and return; Toronto, Kingston, St. Lawrence river, Montreal, and return; and Toronto, Parry Sound, Algonquin Park, Ottawa, Montreal, and return.

Attendance and Grants.-At the concluding meeting, held on Aug. 25, it was reported to the association that those in attendance at the meeting comprised 120 old life members, 8 new life members, 286 old annual members and members of the American association, 125 new members, 682 associates, 100 ladies, and 41 corresponding honorary members. Total in attendance at the association's meeting, 1,362.

A report from the Committee on Recommendation, setting apart grants to the amount of £1,350 for scientific investigations, was adopted. The grants were as follow: To establish a meteorological observatory on Mount Royal, £50; to further investigate the fauna and flora of the Pleistocene beds in Canada, £20; the collection, preservation, and systematic registration of Canadian photographs of geological interest; the biology of the lakes of Ontario, £75; the northwestean tribes of Canada, £75; to organize an ethnological survey of Canada, £75; the establishment of a biological station in the Gulf of St. Lawrence.

Next Meeting.-The association will meet in 1898 in Bristol on Sept. 5-17, and for the presi

dency Sir William Crookes, eminent for his researches in chemistry and in physics and the editor of the "Chemical News," has been advocated. ASTRONOMICAL PROGRESS IN 1897. The number and importance of the astronomical discoveries during the year, though not equal to those of some others, are in the main satisfactory. Excepting the discovery of a few asteroids and a new comet of short period, no new member has been added to the solar system.

The Sun. Our knowledge of the cause of the Sun's heat and light, and of his spots, pores, and faculæ, but especially of his mysterious appendage, the corona, has made little or no advance since our last report. To settle some points in dispute much was expected from observations of the total solar eclipse of Aug. 9, 1896; but on the return of the parties sent out by different countries to observe it-mostly to Norway, Sweden, and Japan-astronomers were disappointed at the meager results achieved, caused by cloudy skies at every station. Another effort, on a still more extensive scale, will be made to observe telescopically, spectroscopically, and photographically the eclipse that will take place Jan. 21, 1898. The line of totality will pass through Central Africa, India, and China, to the southern boundary of Siberia. The width of the total belt will be but 57 miles, and the duration of totality but 219. Yet, owing to improved methods of observation, more can be accomplished in that short time than could have been done at any former eclipse of twice its duration. One of the California parties will be prepared to test the utility of an invention of Mr. Burkhalters, of Oakland, Cal., which was prevented by clouds in Japan in 1896. This consists of a device to proportion the time of exposure of a photographic plate to the intensity of the light in different parts of the field, thus preventing overexposure of the inner corona, and under exposure of the outer coronal streamers, which heretofore has been an impossibility. Astronomers anticipate valuable results from the trial test, which will enable the corona and its streamers to be studied at leisure and compared with photographs taken at future eclipses.

On Jan. 3, 1897, a spot of enormous dimensions appeared on the Sun's eastern limb. It was distinctly visible to the naked eye. With the telescope vast cyclonic movements in the Sun's photosphere were conspicuously visible, on a scale of magnitude of which nothing on our planet furnishes a standard for comparison. It subtended an angle of 100" in diameter, and as a second of arc at the Sun's distance equals 450 miles, it follows that the diameter of the spot was 450 x 100 = 45,000 miles wide, or 1,580,000,000 square miles. This, appearing near the epoch of minimum spot activity, was a great surprise to astronomers. On Jan. 10 it reached its maximum magnitude, and then began rapidly to decrease, and when it was at half of its greatest size disintegration began, resulting in a trail of spots resembling a long train of cars. In the preceding November a spot appeared of 80" in diameter, which remained intact during two rotations of the Sun, or for fifty-two days, affording a rare opportunity to decide whether, after all, the spots are not elevations instead of depressions according to Wilson's theory. Astronomers are now pretty well agreed that the latter, which for one hundred and twenty years has held sway, must be abandoned. His theory was that the Sun is a dark body surrounded by a luminous atmosphere (the photosphere), and that the spots are immense depressions, opening to view the Sun's dark body (umbra), and that the penumbra is the sloping sides of the hole, hundreds if not thousands of miles in depth. The theory appeared so reasonable, and VOL. XXXVII.-A 4

accounted so clearly for their appearance through the telescope, that it met with general acceptance by astronomers. If it is true, the Sun has two atmospheres, the outer (chromosphere), 5,000 miles in thickness; the inner (photosphere), of unknown depth.

The Sun's corona, which near it is a continuous luminous halo, but beyond consisting of streamers several million miles in length, the spectroscope decides to be reflected sunlight. It is never seen but during the few precious minutes of totality. Of the source and nature of the reflecting material we know nothing. The inner corona may be, and probably is, another atmosphere outside the chromosphere, extending to a great height, too thin to be noticed except during totality.

Recent observations of the prominences, which can now be seen with the spectroscope without an eclipse, fully confirm the truth that they belong to the Sun and not to the Moon, as was once thought might be the case. Their source is the chromosphere; but the intensity of the central force that can throw them to a height in one instance 58,000 miles farther than the Moon's distance from the earth is inconceivable, and affords an overwhelming argument against the truth of the Wilsonian hypothesis that the Sun is a dark, cold body.

Lewis Jewell, of Johns Hopkins University, has been measuring a large number of lines in the photographs of the solar spectrum, and has found that there is a difference of several days in the rotation periods of the outer and inner portions of the Sun's atmosphere, the period increasing as the photosphere is approached. He is now engaged upon the reduction of the measures, and the result will be awaited with great interest, as he has perhaps made an important discovery in solar physics.

Evolution of Stellar Systems.-Spiral nebulæ, according to Dr. Isaac Roberts, the distinguished stellar photographer, afford almost positive evidence of evolution of the nebulæ into suns and stellar systems. Photographs of these objects-notably those in Pisces, Ursa Major, and Canes Venatici-afford abundant proof when compared with star clusters already evolved. The photographs show the nebulous matter broken up into stars and starlike loci. The brighter stars are well defined, but the fainter ones have nebulous margins, as have those whose brightness differs but little from the nebulosity in which they are immersed. He says that every spiral nebula photographed by him has a stellar nucleus surrounded by dense nebulosity, around which the nebulous convolutions and involved stars are symmetrically arranged, and this is strong evidence that these features are the result of known physical causes and not of fortuitous arrangement. He considers that collisions between solid bodies or streams of meteors are sufficient to account for the vorticose motions as seen in spiral nebulæ. Nova Auriga and Nova Andromeda and many other temporary are evidences of collisions. Photography, therefore, shows us nebulæ in all stages of development from diffused masses of matter, like the great nebula in Orion, through spiral nebulæ, to clusters of stars.

stars

Celestial Spectroscopy.-Spectroscopic analysis of the light from self-luminous heavenly bodies continues with unabated enthusiasm. Some observatories make it a special and exclusive study. Zeta Puppis presents an abnormal spectrum, giving, in addition to the usual hydrogen lines, a second series of rhythmical lines. Some of these are also to be seen in 29 Canis Majoris and Y. Velorum, some being bright and others dark.

There has been a suspicion that helium is a mixture of two elementary gases, as by a process of diffusion it is possible two get to gases of widely

different densities. Samples of heavy and light gas were examined with a concave grating of 15,000 lines to the inch, and in no case was any difference found in the spectra of various samples. The helium line was discovered in the yellow of the solar spectrum twenty-five years ago, but until lately no representative could be found on the earth. As it was always seen close to the D2 line of sodium, it is also known as D3. The spectroscope reveals the existence in the sun of 23 substances that we are familiar with here, but no oxygen or gold.

Prof. Pickering's recent report announces the safe arrival at the Harvard station, Arequipa, Peru, of the great Bruce photographic telescope, which is under the skillful management of Prof. Solon I. Bailey. It is devoted to photographing the spectra of faint stars, with the large prism placed before the object glass. A large number of objects having peculiar spectra have been detected, including 21 new variables, two new stars, Nova Carina and Nova Norma, also a new variable of the Algol type, W. Delphini, having a variation of 271 magnitudes. A new star has also been discovered in Centaurus by Mrs. Fleming on examining some of the Draper Memorial photographs taken at Arequipa. No trace of it could be seen on the 55 plates taken from May 21, 1884, to June 14, 1895. But on plates taken on July 8 and 10, 1895, its magnitude was 72. In December following it had sunk to the eleventh magnitude. It was discovered from the peculiarity of its spectrum as taken on July 18, which resembles that of the nebula surrounding 30 Doradus, and also of the star Argentina, General Catalogue 20937. Its spectrum, examined visually on Dec. 19, was monochromatic, like nebula, New General Catalogue 5253.

At Harvard College Observatory an immense amount of work has been done, as the following breviary will show: During 1896 20,000 photometric light comparisons were made, 4,192 to determine the form of the light curve of the Algol-type variable W. Delphini, 3,436 of U. Cephei, 1,616 of Z. Herculis, 748 of T. Andromeda, 752 comparisons of Omicron Ceti, and many others, including 26 eclipses of Jupiter's moons. A study was made of parallel lines, similar to the assumed double canals of Mars, with the result that is unfavorable to their duplicity. In addition, 2,508 photographs have been taken with the Draper telescope, and 2,770 at Arequipa with the Bache photographic telescope. Many peculiar spectra have been found on the plate, 21 of them having the hydrogen lines bright. All these photographic plates are dated, numbered, and preserved in a fireproof building.

Motion of Stars.-The spectroscope, in its improved form, is being used to determine the velocity of approach or recession of stars to or from our system. In “Monthly Notices of the Royal Astronomical Society of England" for June, 1897, is the result of measures by H. F. Newell with the Bruce spectroscope attached to his 25-inch refractor at the Cambridge Observatory, England, with the following results: Recession Alpha Tauri (Aldebaran), 30 miles a second; Alpha Orionis, 10-6 miles. Approach Gamma Leonis, 37-5 miles; Arcturus, 6-8 miles.

Broadening of Lines.-Dr. Zuman has discovered that the spectral lines in a magnetic field are broadened. This fact is considered of special importance in connection with astrophysical science. Prof. Lodge has succeeded in showing that the lines not only broaden, but are split up into twos and threes and even more. Dr. Zuman's discovery is considered the most important that has been made during the present year.

Nova Auriga.-This remarkable temporary star, which in less than two months in the beginning of

1892 changed from the fourth to the fourteenth magnitude, and then increased to the 9.7th, and so remained for three years, finally changing into a nebula, has recently decreased again to the eleventh magnitude. Nothing has been more puzzling to astronomers than the behavior of this extraordi

nary temporary star.

New Double Stars.-The discovery of double and triple stars has reached enormous proportions, which raises the question whether single stars like our sun, which is also a star, are not the exception instead of the rule. "The Monthly Notices" for May, 1897, contains a list of 146 discovered at the Cape of Good Hope Observatory. The position angles, distances, and magnitudes of the components and their places for 1900-0 are given. The closest pair is 06". Recent observations of the southern sky by Dr. T. J. J. See, while at Mr. Lowell's temporary observatory at the city of Mexico, discovered several new pairs, and several double and wide pairs which he resolved into triple systems. One which deserves particular mention is Mu Velorum, of nearly the third magnitude, and its companion, of the eleventh. This pair was previously discovered by Russell, of Sydney, Australia. Dr. See, in the "Astronomical Journal," No. 399, says: "Assuming that there is no typographical error in the angle given, it is clear that we have here a case of rapid, direct motion; a change of 57-2° in 16-72 years implies a period not far from a century." He finds that Alpha Phoenices and Eta Centauri are binaries, and many others discovered subsequently.

Prof. S. W. Burnham, of the Yerkes Observatory, the distinguished double-star discoverer and observer, condemns many of the pseudo orbits of alleged binaries. Among those recently criticised are Lambda Cygni and Xi Aquarii. He gives in several astronomical publications diagrams of the supposed orbits, and shows in the case of Lambda Cygni that a straight line satisfies the observed positions of the components better than Prof. Glasenapp's ellipse with its 934-year period, and that in the case of Xi Aquarii it may have any period between three hundred and fifty years and 1,578-33 years. All this, he says, is the result of a premature attempt to fit orbits to such stars after thay have been observed through but a small part of their orbits. These facts are strikingly exhibited in his drawings and comments thereon.

Spectroscopic Binaries.—Prof. Pickering announces the spectroscopic duplicity of Mu1 Scorpii from an examination of the Draper Memorial photographs by Prof. Bailey, Arequipa. The spectrum is of the first type, and also contains lines characteristic of the Orion stars. The spectra of both Mu1 and Mu are close beside each other on the negative plate, and on some plates they present a very similar appearance. The lines in the spectrum of Mu are always single and sharply defined, but those of Mu1 sometimes grow broad and hazy, and then double. The same changes were noted by Mrs. Fleming on plates taken in 1892 (Oct. 2) and in 1894 (July 20 and 31), which leaves no doubt that one of the components is a single star; the other, Mu', a spectroscopic double. The period of Zeta Ursa Majoris is fifty-two days, of Beta Auriga 3d 2h 46m, while that of Mu' is only 34h 42m 30s in a circular orbit. Another spectroscopic double having the same period as Beta Auriga is the star Lacaile 3105-right ascension 14h 40m 78; declination south 25° 5' 18".

Prof. A. Belopolsky has found that Alpha' Geminorum, one of the companions of Castor, is also a spectroscopic binary. In January, 1896, he began the investigation of this star by spectrum photography, and he found as the result of 30 photographs

taken between January and April that the star is a close spectroscopic binary. With an exposure of one hour the spectrum showed H. lines and the stronger lines of iron. On reducing the several values obtained, it was found that there was a periodicity of 29 or three days. The velocities and the values for the period obtained during January and February, compared with the others, showed a discrepancy that can not yet be explained. This may be caused by a rapid motion of the line of the apsides in the direction of the orbital motion, or perhaps an odd number of half periods have been lost or gained between April and November. The photographs obtained at Cambridge, however, appear to support Belopolsky's important discovery. We have here, in the triple system of Castor, two periods one of about one thousand years, the other of about three days.

A telescopic binary is a double star both components of which are visible with a telescope and are found to revolve around the common center of gravity. A photo-spectroscopic binary is also a double star, only one component of which is telescopic, the other being a star that no man has seen. If the orbital plane of a binary is coincident with the solar system, there must be a time at each revolution when one star will be approaching the earth and the other receding from it, and vice versa. As a spectroscope takes cognizance of the motion of a star toward or from us in the line of sight (which a telescope does not), and as each star gives a spectrum crossed by lines, it will periodically happen, while neither star is moving toward or from us, that all lines on the photographic plate will appear single. When one star begins to approach and the other to recede from us the lines will appear hazy, but when the approach and recession of the stars reach a maximum the lines in the approaching star will be displaced toward the violet, and those from the receding star toward the red end of the spectrum, causing the lines to appear double. These lines, being photographed at short intervals, produce an imperishable record for comparison to ascertain the period of revolution by the periodic doubling of the lines. But for the assistance of photography this feat never could have been accomplished. In the case of Mu1 Scorpii their velocities in all probability amount to several hundred miles a second.

Telescopic Binaries.-The discovery of suns revolving around suns, and the computation of their orbits and periodic times, has to many astronomers a resistless charm. New ones are constantly being added to the long list of over 1,000 known binary stars. In the time of Sir William Herschel but few were known, though he discovered 50. Xi Ursa Majoris was then found to be the shortest period binary known-sixty-one years; then came Eta Corona, with a period of forty-two years, and, later, Zeta Herculis was found to have a period of thirty-four years. Twenty years ago 42 Comæ Berenices was ascertained to have a period of twentyfive years, and in 1887 the components of Kappa Pegasi were found to revolve round each other in 115 years; and now comes a candidate for the shortest known, only 55 years. The star is Burnham's 83=Laland 909. The shortness of its period brings us a long way over the gap that separates the telescopic from the spectroscopic binaries. The discovery of its periodic time was lately made by Dr. T. J. J. See. His opinion is fortified by a long series of measures, which leave no doubt that his conclusions are correct. The apparent orbit of this rapid binary is: Length of major axis, 0-67"; length of minor axis, 0-16; angle of major axis, 195; angle of periastron, 318; distance of star from center, 0-07; period, five years and a half.

Rediscovery and Orbit of Sirius.-This, the brightest star in the heavens, often called the dog star, was discovered to be double by Alvan G. Clark in 1862, for which he received the Royal Astronomical Society's gold medal. In consequence of the variation of its proper motion, it was long before assumed to be double, being swayed hither and thither by an unseen companion, and a period was computed for it of about forty-eight years. Of course the pair were watched with great care, but the observed path was too short from which to deduce even an approximate orbit, and this resulted in the computation of 12 orbits, varying in periods from 49.5 to 585 years. The last view of its companion was obtained by Burnham in 1890 with the 36-inch telescope at the Lick Observatory, and no telescope in the world could follow it later. For six years and a half it was beyond the reach of any telescope. In the latter part of 1896 Prof. Aitken, with the great Lick glass, rediscovered it. The arc passed over by the companion during its invisibility was 170°. Its position angle when discovered by Clark was 85° + 170° = 225° of arcual motion, from which its period was computed by Burnham, who made it 518 years. The apparent orbit is given in "Monthly Notices" for April, 1897, as: Length of major axis, 14-48"; length of minor axis, 9-32"; star from center, 409"; angle of major axis, 544°; angle of periastron, 251.9°; period, 51-8 years.

Dr. See announces that the binary star Burnham 39582 Ceti revolves in sixteen years. The companion is now near periastron, angle 278°, distance 0.22". This star has not heretofore been suspected to be a short period binary, but it appears from Dr. See's investigations that 1 revolution has been completed since Burnham's discovery in 1875, making it one of the most interesting binary systems in the heavens.

Star Systems. That the heavens afford many star systems besides the clusters is of universal belief, but Proctor's opinion that five of the seven stars comprising the bowl of the great dipper in Ursa Major are thus associated does not meet with general acceptance. In the first place, their proper motions are so small as to form a very slender thread on which to hang so strong a theory. It is, however, favorable to the idea of a physical connection between the five that they all present the same kind of spectrum (A). But Eta, admittedly not belonging to the system, also gives the spectrum A, while Alpha has the spectrum K, and has less than half the velocity in the line of sight of the other six.

Variable Stars.-The discovery of variable stars has been pushed with an energy heretofore unknown. As its prosecution requires no expensive instruments, it opens a fascinating field to amateurs. Dr. S. C. Chandler, editor of "Gould's Astronomical Journal," the best authority on variables, has published in the journal three extensive catalogues, which give full details of 8,622 members. It is the most extensive catalogue extant. The subject is too voluminous to be dealt with here. Only a few of the more remarkable can be noticed. Prof. E. C. Pickering, in "Astronomische Nachrichten," No. 3321, gives an account of the discovery by Prof. Bailey, at Arequipa, of numerous variable stars in certain globular clusters, and their entire absence in others, apparently belonging to the same class. Since then he has found many more, so that their total number now known, including a few found at Cambridge, is 310. The number in only two can be noticed. In the Omega Centauri cluster Prof. Bailey has detected 60, and in Messier 5 (New General Catalogue 5904) 63 have been discovered. In Messier 3 about one ninth of the stars are variable, while in the cluster in Hercules not one varies.