light, we are told, produces first stimulation and then depression, neurasthenia and even loss of memory. To protect us from these terrible ills we require a skin so highly pigmented that the sun's rays cannot influence our delicate nervous organisation. The want of a sufficiency of pigment in the skin, Dr. Woodruff informs us, has played an important part in the history of the world. The decline and fall of the Roman Empire and the decay of Greece were, in his opinion, due to the fact that the military forces of these powers were largely recruited from the northern blonde races. These dominating blondes, bred under cloudy skies, were reduced to impotence because their skins were insufficiently pigmented to resist the baleful influence of the bright sun of the Mediterranean. Light, and not luxury, was responsible. It is not surprising to learn that the conduct of the schoolboys of New York is worse on a bright June day than on a cloudy day in winter, but we should have thought that the author's reminiscences of his own school days would have suggested that there were other more probable causes than the irritating effect of the chemical rays of light upon the schoolboy's nervous system.

It is difficult to criticise an author who, in considering the experimental work of Ferni, whose opinion differs from his own, says, "it seems certain that he has been misquoted, and that the fact is the reverse of what he is alleged to have said." It is surely usual in a scientific treatise to verify references, but here, as elsewhere, Dr. Woodruff appears to have been rather hurried.

While admiring the author's industry and his courage in advancing his contentions, we cannot but consider many of his conclusions unwarranted. With the remark that it is a pity that our slum babies cannot undergo such "torture,' we cannot forbear quoting the following statement of Dr. Woodruff :

"We moderns of the intelligent classes alone violate the mother's instinct to hide away in the dark with her baby, and we ruthlessly thrust it out into the sun's rays, actually strapping the poor little sufferers into their carriages and torturing them with the direct rays of the sun pouring down into their faces."

or

THE German word "heide," like the English heath," is applied to very different types of vegetation. In the narrowest acceptation it signifies a district covered with dwarf shrubs where ling heather predominates, and such a formation is not uncommonly associated with loose, sandy soil. But in north Germany "heide "implies a wood, usually a pine wood, and the same conception attaches to it in other parts of Germany, as, for instance, the Dres dener Heide. Heath is therefore not a formation according to the ecological use of the word, but is applied to land where certain physical conditions prevail, and covers not only stretches of open woodland, but also grass and other moors, and may even be extended to peats and bogs. One feature common to these different formations is the presence of humus, and this is included in the definition given by Ramann.

The suggestive views as to the formation of heaths

advanced by Dr. Graebner in 1901 have become widely known, and have received very general acceptance. Heaths or moors may develop on sands or under water, but in north Germany, at any rate, and not improbably in other countries, much of the heathland has taken the place of forests. Opinions differ as to the causes which have brought about the change. Borggreve and Krause have attributed the disappearance of forests to destruction by animals, but Graebner attaches more importance to continual draining of salts into the lower layers by percolating water. Another factor, which has not been sufficiently emphasised by Graebner, is the action of those bacteria which give rise to humus in the absence of air. Want of air no less than impoverishment of the soil plays its part.

Although the book is written for the practical man, Dr. Graebner has included a certain amount of purely scientific matter where it has a bearing on economic problems, but the chapter written by Mr. O. von Bentheim is more especially concerned with practical considerations. It is evident that profitable cultivation of heath land requires not only careful and scientific farming, but in some cases success can only be attained by general cooperation of the farmers either as a society or under Government supervision. The preparation of the land for agricultural farming or for tree planting is discussed in detail; as a preliminary deep ploughing is advisable and quite necessary where moor-pan has formed. Moor-pan (Ortstein) is practically a layer of stone, which is formed when percolating water containing humates reaches layers of soil which are rich in mineral salts; the humates are precipitated, and bind the particles of soil into a stratum of stone, which as it thickens cannot be penetrated even by tree roots.

In the latter portion of the book the different formations are considered from the purely botanical standpoint according to the characteristic plants. The problems connected with the cultivation of heaths are complicated but interesting; for this reason opinions of Dr. Graebner, who has made a careful study of the subject, are the more valuable.

the

I Nuovi Indirizzi e le Promesse della Odierna Antropologia. By Fabio Frassetto. Pp. 71. (Castello : C. E. S. Lapi, 1905.) Price 3 lire.

THIS little work consists of a series of four lectures which the author delivered as an introduction to his course of anthropology in the 1904-5 session of the University of Bologna, where, after a break of twenty years, he has taken up the work begun by Sergi before his removal to Rome. Appropriately enough, the first lecture of the four deals with Sergi and his principles of skull classification, and sketches very briefly the types and the deductions which Sergi draws from them-Eurasian and Eurafrican forms, and five species of pygmies at the same time pointing out that many of these views are only provisional. Dr. Frassetto holds that just criteria of race are of the utmost importance, not only for the sociologist, which most inquirers would be prepared to admit, but also for the medical man, who will more readily diagnose the maladies which he has to treat, in proportion as racial morphology and pathology are determined with precision and at the same time it becomes possible to classify the individual patient from an anthropological point of view. If he is too sanguine in this, another point on which Dr. Frassetto insists does not seem beyond the range of practical politics; this is the development of pædagogic anthropology, which shall regulate the education of the individual child by scientific principles. Even here, however, at any rate in our own case, the problem of feeding the child and of providing it with a healthy body will probably

occupy the first place for some time to come, so far as elementary education is concerned.

The second lecture deals with the work of Maggi and the morphology of the cranial bones. This is a subject on which Dr. Frassetto has himself published some valuable studies. He would have done well to indicate in his lecture that some, at any rate, of the new views on the number of centres of ossification are based on what seems to be an unduly small collection of cases. The third lecture treats of de Giovanni and his work in clinical anthropology, which deals with a patient according to his morphological characteristics rather than as an individual. Finally, we have a sketch of the work of Lombroso on criminality and genius. Dr. Frassetto insists on the need for scientific treatment of criminals, especially those of the habitual class.

It goes without saying that in brief studies of this sort we only find the broad outlines, without qualification or hint of difficulties, and herein lies perhaps a certain danger for the unfledged anthropologist who attends the academic courses. The book is, however, readable, and offers an example to English anthropologists who wish to in terest a larger public.

N. W. T.

Catalogue of the Lepidoptera Phalaenae in the British Museum. Vol. v. Catalogue of the Noctuidæ in the Collection of the British Museum. By Sir George F. Hampson, Bart. Pp. xvi+634; pls. lxxviii-xcv. (London: Printed by Order of the Trustees, 1905.)

WE Congratulate the authorities of the British Museum and the indefatigable author on the steady progress of this important work, of which a fresh volume appears, with almost clockwork regularity, every two years. The present volume is the second devoted to the Noctuidæ, and contains the second subfamily, the Hadeninæ. These are much less showy moths than those dealt with in the first three volumes of the series, and are more subdued in their colouring; but they are perhaps more interesting to British entomologists, for the family is fairly well represented in the northern hemisphere, although in a work devoted to the moths of the whole world, British, or indeed European, species are few and far between. The work is profusely illustrated, the descriptions are full but not too lengthy, and short notices of larvæ, where known (some of which are here published for the first time), have been included. The keys to the genera and the tables of species will also be found very useful by working entomologists. A table of the phylogeny of the 78 genera into which the author divides the Hadeninæ is given on p. 2, but without comment, which we think is wise, for such tables, in the present state of our knowledge, can only be tentative; and comments on the supposed affinities of genera have often a tendency to become too dogmatic.

Synonymy cannot, of course, be given in full in a work of this character, but in the case of European species, which are most burdened with it, the necessity for further details is largely obviated by a reference to Staudinger's last catalogue; still, we think that, in the case of the few British species, Barrett's "Lepidoptera of the British Islands "might have been referred to.

We heartily commend this important book to the working entomologists of all countries. Five volumes have already appeared, but if it is ever completed it will certainly far exceed in bulk the twenty-seven volumes of the "British Museum Catalogue of Birds." Hitherto it has been wholly the work of one man, and we hope that when he finally lays down his pen, a very large proportion of the gigantic task of describing the moths of the world will have been accomplished by his hands.

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 intended for this or any other part of NATURE. No notice is taken of anonymous communications.]

The Spinthariscope and Retinal Excitability.

I HAVE recently been making a series of observations upon retinal excitability, and have used, among other test stimuli, the well known flashing scintillations of a pocket spinthariscope. The special value of the instrument in this connection is the subminimal or minimal intensity of the retinal excitation judged by the disappearance or appearance of visual sensation. The method used by physiologists for ascertaining whether any given condition alters the excitability of a tissue is that of stimulating periodically the tissue by subminimal or minimal exciting agencies under constant conditions and then changing one of these conditions; if, as the result of such change, the subminimal or inadequate stimulus becomes adequate, the excitability of the tissue has been raised by the change; if, on the other hand, the minimal or adequate stimulus becomes inadequate, then the excitability of the tissue has been lowered by the change.

It is well known that with the ordinary pocket spinthariscope no luminous effects are seen unless the eye has been rendered sufficiently sensitive by some minutes' darkness; this is especially the case during the daytime, the effects at night being almost instantaneously visible. The stimulation of the retina by the scintillating flashes is thus of the minimal order, and becomes subminimal when the eve is exposed to daylight.

It is thus possible to place the eye under different ronditions, and to determine by means of the visibility of the flashes in the spinthariscope whether the retinal excitability has been raised or lowered; the method has the merit of great simplicity, all that is necessary being to go into a dark room and immediately look through the instrument; the time necessary for the appearance of the first visible luminosity and for the full appearance of the flashes is longer the lower the general excitability of the retina.

A further point of physiological interest is brought out by simple experiments along these lines. It is well known that when the eyes at night look at groups of stars, faint groups not in the direct line of vision are distinctly seen which disappear when the gaze is directed towards them. There is an accumulating mass of evidence that this familiar experience is the sensory aspect of a modified condition of the retina, the modification consisting in an augmented excitability of the peripheral portions of the retina. It appears probable that such peripheral augmented excitability is localised particularly in the outer segments of one set of retinal elements, the rods, which contain the visual purple discovered by Kühne. The rods are extremely numerous in the peripheral region, and constitute the sole elements in nocturnal birds such as the owl. The visual purple of the rods is blanched by light, especially by the more actinic rays, but the blanching disappears with darkness, and this re-constitution of the substance is associated with the presence of the choroidal pigment. There is thus an adaptation process which renders the dark-adapted eye more excitable than it otherwise would be, and this augmented excitability is especially prominent in that part of the retina which contains large quantities of rods, viz. the peripheral portions. The specialised elements of the central part of the retina (macula lutea) consist in man almost entirely of cones; it is undoubted that in daylight this part is the most excitable region, and that it possesses to a remarkable degree the capacity of localised response, thus enabling two sources of light to be discriminated as distinct when SO near together that they subtend an extremely small angle. At night, or with the dark-adapted eye, the whole condition is modified, and the peripheral part of the retina has its excitability augmented more than the central part, so that sources of light of subminimal intensity for the latter are adequate to excite the former; these facts are readily demonstrable by means of the spinthariscope.

Thus if in the day time the observer takes the spin

thariscope into a dark room he will notice that the first visible effect is a slight general luminosity when the visual gaze is directed down the optical centre of the little tube. If, however, the gaze is shifted to the side of the tube, the whole spinthariscopic display with its scintillating flashes becomes distinctly visible. On opening the door of the dark room and going into the daylight the subsidence of the central and peripheral responses can be followed, whilst on returning to the dark room the re-appearance, first peripheral and then central, can be observed with great distinctness. The essential difference between the lightadapted eye and the dark-adapted eye is thus readily demonstrable, and the rapidity, as well as the efficiency, of such adaptations can be easily followed if the eye is sub jected to appropriate periods of darkness and of light.

It is evident that with such a minimal test the influence of a large number of other conditions may be investigated. Without going into these, I may mention one of considerable interest. If the observing eye is kept in the darkadapted stage by means of a removable bandage, whilst the other eye is subjected to periods of darkness followed by daylight illumination, then the visible effects in the dark room still indicate modification. In my own case illumination of one eye causes a distinct lowering of the retinal excitability of the other one, this being especially characteristic of the peripheral region of the retina. In this connection it should be remembered that the pigment cells alter in the frog as the result of illumination, and that this alteration has been shown by Engelmann and v. Gendre to occur when, the eyes being kept dark, the skin of the frog is illuminated; one eye thus influences the other. The spinthariscope with its constant minimal excitation affords a means of demonstrating this consensual effect. It appears to me that with slight modifications the instrument may become of considerable clinical value. For clinical use it has the merit of being portable and easily used. It furnishes, with no apparent decrease through time, use, &c., a constant and continually recurring stimulus which is of threshold exciting value. It can be easily applied to either the central or peripheral portions of the visual field, and gives indications which are comparable with each other, and are only altered through alterations in retinal excitability. No doubt it can be modified in form so as to be still more useful from the clinical point of view, but even in the form in which, as a scientific toy, it is now presented, its use will show whether the central or peripheral retinal excitability is abnormal, and I anticipate that before any changes can he observed with the ophthalmoscope, it will be possible by its means to ascertain alterations in retinal excitability in the early stages of disease. FRANCIS GOTCH.

Physiological Laboratory, Oxford, June 10.

Solar Changes and Weather.

66

IN NATURE of June 8 (p. 129) Dr. Lockyer says:- Up to the present time (italics mine) those who have been attempting to explain variations of weather on the supposition of solar changes have been looking for the effect of solar action as either increasing or decreasing simultaneously the rainfall over the whole earth.

This is, I think, somewhat inaccurate. The possibility of a given phase of solar change being causally related to opposite weather conditions in different regions has been recognised by many, if I mistake not, for a considerable time. I might instance M. Angot, who expressly affirms it in his "Traité de Méteorologie," published a few years ago; and what he there says on the subject indicates a certain currency of the idea previously, of which (no doubt increasing) currency back volumes of NATURE and other serials give evidence. The idea of a barometric Pe-saw in Asiatic regions, connected with sun-spots, was discussed in NATURE So far back as the 'seventies, if I remember rightly. A. B. M.

64

Angot, &c., but still there seems to be a tendency for the solar changes, that is, changes indicated by sun-spots, to be considered as affecting the whole earth simultaneously at any one epoch. It would have been more correct for me to have written Up to the present time many of those who have, &c.," than Up to the present time those who have, &c.," but at the time of writing I was considering more the generally conceived impression as to the relation between sun-spots and meteorological changes than the results of investigation of any particular region on the earth's surface.

To take a case in point, two years ago M. Charles Nordmann (Comptes rendus, vol. cxxxvi., p. 1047, May 4, 1903) communicated to the Paris Academy of Sciences a paper entitled La Périod des Taches solaires et les Variations des Températures moyennes annuelles de la Terre." This title implied that the solar changes were affecting the whole earth similarly, but the investigation was only restricted to the equatorial regions, where the conditions are most favourable for such an inquiry. Further, I am inclined to think that the result he obtained will be found to apply only to that portion of this equatorial belt lying between about longitude 40° E. and 140° E. The reason for this is that out of the thirteen stations in all which he employed, eight were included in this region (five stations of which were given double the weight of the others), and only five were situated in the other part of the belt. If it were possible to include more stations in the western hemisphere, the relation between temperature and sun-spots which he obtained might probably be reversed. WILLIAM J. S. LOCKYER. Solar Physics Observatory, South Kensington.

Fictitious Problems in Mathematics.

99 occur in No state

ON reference to § 156 of " Rigid Dynamics," it will be seen that the definition there given is identical with that contained in Dr. Routh's letter of May 25, with the exception that the words "When the bodies my edition instead of "When bodies. ment is made as to what is meant by saying that a body is perfectly rough, and it is against this latter mode of expression that my attack is directed. For this reason it may be maintained that the definition given in the book in which the problem occurs is inapplicable to the problem as at present worded. Otherwise we appear to be dealing with a plank such that in the given circumstances, one of which is resting on a smooth table, the amount of friction necessary to prevent sliding can certainly be called into play, and this is apparently inconsistent with Dr. Routh's interpretation.

I would challenge your correspondent, 'An Average College Don," to point to any text-book containing an explicit definition of a perfectly rough body (not bodies); also a perfectly smooth body. If he succeeds, I anticipate no difficulty in furnishing him with examples of questions which are either inconsistent with his definition, are ambiguously worded, or are open to some equally serious objection. G. H. BRYAN.

History of a White Rhinoceros Skull.

THE interesting specimen of the skull of the white rhinoceros (R. simus) referred to by Prof. H. F. Osborn, of the American Museum of Natural History, New York, in NATURE of June 8 (p. 127), was, thanks to the kindness of Mr. Graham, carefully examined by me before its sale. Its chief interest lay in the fact that the horns had never been detached, and consequently showed the true position of the nasal horn in this species; it was at right angles to the downward sloping surface of the nasal bones, thus bringing it into a most efficient position for attack.

There is a fine skull of this species in which the horns have been placed in their true position; it is numbered 2154 in the osteological series of the Museum of the Royal College of Surgeons. The animal was shot by Gordon Cumming.

The length of the nasal horn is 860 mm. (34 inches). C. STEWART.

The Romance of the Nitrogen Atom. WITH reference to the interesting letter by Dr. Irving in NATURE of June 15 on "The Romance of the Nitrogen Atom," I should like to point out that ammonia is not so stable as is sometimes imagined. I have shown recently not only that ammonia decomposes slowly at a temperature of about 700° C., but that the decomposition is irreversible (Proc. Roy. Soc., June), so that it will proceed until no ammonia remains. The rate of decomposition decreases rapidly with temperature, but it appears probable that even at the ordinary temperature of the air the decomposition must still proceed, although with excessive slowness. mixture of nitrogen, hydrogen, and ammonia would thus appear to be in “false equilibrium," in the same way as a mixture of hydrogen, oxygen, and water vapour, but in the opposite sense. The "silent discharge" will decompose as well as synthesise ammonia, and brings about a state of equilibrium. Sparking has also the same effect. In these cases the equilibrium is a true one, so long as the experimental conditions remain unaltered, and it ensues when the rates of formation and decomposition of the ammonia are equal.

University College, Cardiff, June 17.

E. P. PERMAN.

A

Notes on the Habits of Testacella, UNDER the above heading in NATURE, vol. xxxiv. p. 617 (October 28, 1886), Prof. E. B. Poulton recorded the capture of twenty-two specimens of this rare slug upon a wall in Oxford. On that occasion there had been exceptionally heavy rains, and it was suggested that the animals had been driven out of their usual habitat, the earth, as it became sodden with moisture. I am in a position to confirm the accuracy of this suggestion. Last evening I captured five specimens of Testacella haliotidea upon a stone wall near Charterhouse. The slugs were apparently crawling out of the ivy which thickly clothes the top of the wall, and were making their way back to the earth. During the previous eight days no less than 3.80 inches of rain fell at this place. It seems probable that the slugs had taken refuge in the dense shelter of the ivy while the soil was unfit for them, and that on the return of hot, dry weather were once again seeking their OSWALD H. LATTER.

subterranean quarters.

Charterhouse, Godalming, June 15.

Researches on Ovulation.

I SHOULD be greatly obliged if you would allow me to state in your Journal that the paragraph on "ovulation " in relation to oestrus on p. 517 of my text-book on the "Vertebrata," which was issued in March last, contains references to discoveries which were at that time unpublished, and that by inadvertence I omitted to direct attention to this. The information was supplied to me by Mr. Walter Heape. The facts relating to rabbits were discovered by him, those relating to ferrets and dogs by Mr. F. H. A. Marshall. These observations, with others, have recently been separately communicated to the Royal Society for publication in the Proceedings. A. SEDGWICK.

Trinity College, Cambridge, June 16.

ABORIGINAL METHODS OF DETERMINING THE SEASONS.

AN

N important and timely confirmation of the astronomical significance attached to the stone circles of Britain, and to the pyramids and temples of Egypt, comes from the Far East. From an interesting paper (Journal of the Asiatic Society, Straits Branch, January) by Dr. Charles Hose, who has made a special study of the subject, we learn that the natives of Borneo are at the present day using just the same general principles in determining the advent of their agricultural seasons as were used by the early Britons and the ancient Egyptians between one and two thousand years B.C. It will be remembered that, in Greece, Mr. Penrose observed (see NATURE, April 6) that the Hecatompedon and the older Erechtheum,

built about 1495 B.C. and 2020 B.C. respectively, were oriented to the cluster of the Pleiades at its heliacal rising on May morning. In Egypt, Sir Norman Lockyer found that the same asterism, as the deity Nit-Isis, was probably employed as the warning star for sunrise at the vernal equinox ("Dawn of Astronomy," 1894, p. 388).

Although in Great Britain there are a great number of stone circles, their astronomical significance has, until quite recently, not been satisfactorily understood. However, the recognition of Stonehenge as a solstitial temple (Proc. Roy. Soc., vol. Ixix. pp. 137-147) led to an inquiry into their possible character as observ atories, used by priest-astronomers to determine the advent of the seed-time and other festivals, and the investigation met with gratifying results at the outset. In the case of "The Hurlers," a group of three stone circles situated near Liskeard, in Cornwall, prima facie evidence was found that they were arranged in their present positions, and the stones around them placed in accordance, that the officiating priesthood could announce to the people the arrival of the crucial seasons in the agricultural year. Among the stones used as azimuth marks at "The Hurlers," there is one with an amplitude of E. 11° N., which would mark the exact heliacal rising of the Pleiades on May morning about the year 1600 B.C. (Proc. Roy. Soc., March 30). In addition to the Pleiades, it has been found that the belt of Orion was frequently used as the warning sign.

SO

Now we learn from Dr. Hose's researches that, at the present time, the natives of Borneo, more especially the Dyaks, are using the same stars in much the same way to determine the season of the year ordained by the local meteorological conditions as the time for the preparation of the ground on which they hope to grow their food supply for the ensuing twelvemonth. During the semester October to April the prevailing wind in Borneo is from the north-east, and brings rain with it; during the other six months of the year the direction of the prevalent wind is changed, but it brings none of the month-tomonth variations of conditions which-in lieu of more refined knowledge-would lead the agriculturist of the temperate zones to a more or less approximate knowledge of the season.

In Egypt it was the advent of the Nile flood which fixed the seed-time, and for which the celestial heralds were observed; in Britain it was, as it is now, the advent of the warm, sunny weather that was the matter of importance; in Borneo it is the commencement of the driest season that has to be recognised, because the land which is to be cultivated is overgrown by jungle or forest, and, before seed may be sown thereon, a clearance must be effected. Like the Malayans, the Dyak might use the moon as his indicator, but then, like the Malayans, he would probably get about eleven days wrong every year, duration. a serious matter where the dry season is of short The variation of the length of the day is too small in the tropics to give a definite cue as to the commencement of any special season. Consequently, the Dyaks and many of the smaller neighbouring tribes have recourse to the stars, and the stars chosen as the heralds are the Pleiades ("bintang banyak ") and Orion's belt ("bintang tiga "). The native names are borrowed from the Malays, and this probably indicates that the similar use of these stars is not totally unknown among the latter. The alternative expression used by the Dyaks in naming the Pleiades is "Apai andau," meaning "the father of the day," probably so called because it is the heliacal rising of them that the natives watch for before commencing their clearing process. In Borneo it is, at present, merely an observation of the Pleiades

LOGICAL CONGRESS.

The method of making the determination is as follows:-The surrounding terrestrial phenomena suggest the approach of the dry season, and two men are then sent into the jungle-which probably means any open space with a clear horizon-to await the celestial sign. After watching for a few nights, may be a month, the Pleiades are seen on the horizon just before the light of the rising sun overcomes that of the stars. Then the messenger-astronomers return to their village and announce the fact, and the work on the forest is commenced. Should the tribe have been so misled by the workings of terrestrial nature as to delay the making of the observation until Orion's belt rises before daylight, it means that they must work double-shift" in order to get their ground cleared in time for the vegetable matter to dry thoroughly ere the season for burning it comes round. After this recognition of the season the interest of the tribe in celestial phenomena becomes dormant until the services of the latter are again required. Not until the Pleiades reach the zenith before sunrise do they consider it advisable to set fire to the refuse, for unless the latter has had enough time to dry thoroughly it will not be completely consumed, and the ground will be of no use for ricegrowing.

With the neighbouring tribes, the Kenyahs and the Kayans, the method of determining the seasons is rather more scientific, exhibiting an advanced state of knowledge. These people are acquainted with the various phenomena attending the apparent diurnal and annual movements of the sun. They know that the noon shadow is the shortest, and that it always lies in the same straight line, sometimes to the north, sometimes to the south. Consequently, they utilise this knowledge by measuring either the length of the shadow cast by a gnomon set up vertically on levelled ground, or else the length of a beam of sunlight projected through a small hole in the roof of a hut upon a plank, laid horizontally on the floor by packing it up until round discs will not roll when placed on edge on its surface. The shadow, or beam of light, is measured by means of a stick, on which there are a series of notches. The distance of each notch from the end of the stick represents the length of shadow which experience, tinged, maybe, with superstition, has taught these people to recognise as favourable, or the reverse, for the prosecution of their various agricultural operations. The stick, known as "asa do," is carefully preserved in the keeping of an older member of the tribe, duly elected to this office on account of his superior wisdom and his incapacity for more strenuous manual labour, and it is he who watches that the beam is not measured obliquely, and announces the advent of the favourable season for sowing operations to commence.

A striking phase of the question, showing how limited is the original knowledge, possibly appears in the selection of the Pleiades and Orion's belt as the "warners." Why should these two groups be selected by so many different tribes in so many widely separated ages? A plausible explanation seems to be that their forms are instantly recognisable. Whilst the aboriginal watcher would probably not be able to recognise the isolated, though bright, stars of the large constellations, especially if, as is the case with the Dyaks, no azimuth marks were employed, he could not possibly confuse either of these with any other group of stars.

WILLIAM E. ROLSTON.

THE International

Ornithological Congress assembled in London on Monday, June 12, under the presidency of Dr. R. Bowdler Sharpe, and continued in session to the end of the week. The congress was instituted at Vienna in 1887 under the patronage of the Crown Prince Rudolph of Austria. The second congress was held at Buda-Pesth, and the third at Paris in 1901, so that the London congress was the fourth of the series. It was well attended

by both British and foreign ornithologists-to the number of rather more than 300. They commenced their work on June 12 by an informal meeting at the Imperial Institute, South Kensington, which was the headquarters of the congress during its session.

The British ornithologists were well represented by Dr. Hartert, of Tring, and Mr. Bonhote, of Cambridge, who acted most efficiently as secretaries, while Mr. C. E. Fagan, of the British Museum, looked These gentlemen after the finances as treasurer. were assisted in their duties by Dr. Godman, Mr. Meade-Waldo, Mr. Ogilvie-Grant, Dr. Penrose, the Hon. Walter Rothschild, Dr. Sclater, and Mr. Witherby, who were all members of the organising committee. Many other well known British ornithologists attended the meetings, such as Sir Walter Buller, Dr. Butler, Mr. Dresser, Colonel GodwinAusten, Mr. Harting, Mr. Pearson, Mr. Pycraft, Mr. The Howard Saunders, and Mr. D. Seth-Smith. French ornithologists represented by Dr. Oustalet and Dr. Burcau, the German by Graf Hans v. Berlepsch, Dr. Blasius, and Prof. Reichenow, the Dutch by Dr. Büttikofer and Baron Snouckaert van Schauburg, the Austrian by Dr. Lorenz and Dr. Reiser, and the Italian by Dr. Giglioli and Count Arrigoni degli Oddi. From America came Mr. F. M. Chapman and Dr. Stejneger, from Switzerland Prof. Fatio and Dr. Studer, from Russia Dr. Bianchi and Baron Loudon, from Bulgaria Dr. Paul Leverkühn, from Canada Mr. Fleming, from Hungary Dr. Herman, and from Belgium Dr. A. Dubois, all names well known in ornithological science.

were

The first general meeting of the congress took place in the morning of June 13, when Dr. Oustalet, the last president, gave up the chair to Dr. Bowdler Sharpe, the new president, who delivered a most instructive address on the origin and progress of the great national bird-collection in the British Museum, which is under his charge. The meeting was then divided into five sections :-(1) systematic ornithology and distribution; (2) migration; (3) biology and oology; (4) economic ornithology; and (5) aviculture, which sat at stated periods throughout the week. To the first section, which was presided over by Dr. P. L. Sclater, F.R.S., about fourteen communications were made, among which were papers by Graf v. Berlepsch on new neotropical birds, by Mr. Pycraft on the importance of the study of nestling birds, which was illustrated by various pregnant instances of the secrets they have already revealed and are likely to betray in the future, and by Padre Schmitz on the birds of Madeira. In this section also, Dr. Reiser, of Serajevo, exhibited the series of NorthBrazilian birds which had been obtained during Dr. Steindachner's recent expedition to the Rio St. Francisco, and Mr. Walter Rothschild showed his unique copy of "Les Voyages de Sieur B.," with the map attached, which contains much information on the now extinct birds of the Mascarene Islands.

In the second section, which met on Tuesday and Saturday, with Dr. Herman, of Buda-Pesth, in the chair. Mr. J. H. Fleming gave particulars of an unusual migratory visit of Brunnich's murre to the