but inured to rough work in a wild country-commenced, in 1886, a series of expeditions in the "High Alps" of the Antipodes.

The Southern Alps proper, for over one hundred miles, form the backbone of the South Island, running roughly from north-east to south-west, the crest of the chain lying much nearer to the western than to the eastern coast. In the neighbourhood of Aorangi the former is about twenty miles away, while the distance of the other is quite five times as much. Thus the valleys fall more rapidly towards the west than towards the east, on which side also a wide tract of plain separates the sea from the foot of the hills. But in one respect, the New Zealand Alps, at any rate on their eastern flank, differ from their European namesakes, for they are pierced more deeply by the lowlands. Even at the foot of Aorangi, in the vicinity of which almost all the highest peaks are situated, the comparatively level floor of the Tasman valley is rather less than 2500 feet above the sea. Thus, although the New Zealand peaks are considerably lower than those of the European Alps-for few of them surpass 10,000 feet, and the highest summit of Aorangi is only 12,349 feet -they tower as high and as steep above their actual bases as the Oberland giants above the valley of the Lutschine. As Mr. Mannering says, Aorangi rises "for nearly 10,000 feet from the Hooker glacier, and Mount Sefton 8500 feet from the Mueller glacier, whilst the western precipices of Mount Tasman (11,475 feet) are stupendous." These words indicate another peculiarity of the New Zealand Alps. Here the snow-line lies very much lower than in Switzerland; in this central district it is only about 5000 feet above the sea. Thus the glaciers are actually greater, and descend much below those of Switzerland. The Tasman glacier, which may be compared with the Gross Aletsch of that country, is from 18 to 20 miles long, and terminates at a height of 2456 feet above the sea. On the western side the ice approaches occasionally to within 600 feet. Thus in the New Zealand Alps the Alpine climber meets with the same difficulties, and is rewarded by the same class of scenery, as he finds in the Old World amid peaks and passes three thousand feet higher. For instance, the Hochstetter Dome, first ascended by Dr. von Lendenfeld, though only 9315 feet above the sea, and presenting no special difficulties, is a very long and laborious excursion over ice and snow. Mr. Mannering and his two companions found it "twelve hours' hard going" from their camp-von Lendenfeld's party were out more than double the time.

But great as are these glaciers, they are, like those in our own hemisphere, attenuated representatives of their predecessors -for New Zealand also has had its Ice age. Once they extended far away into the lowlands. There, erratics and ice-worn rocks abound for miles. Lakes Tekapo and Pukaki are dammed by moraines, and in the valley of the Tasman River some singular terraces can be traced for 40 miles from the point where they commence, near the end of the glacier, at a height of some 2000 feet above the valley. Much débris is still transported by the glaciers of the eastern side of the chain, but those on the western are cleaner. The main range consists of stratified rocks, which disintegrate, as the climber soon discovers to his sorrow, rather readily; and Mr. Mannering attributes the difference in the amount of débris to the fact that the

beds have a westerly dip. This, at any rate, accounts for the precipitous character of the eastern face of the mountains. We infer, also, that denudation has been more rapid on this side, for Aorangi projects in advance of the watershed, like the Viso and other peaks on the Italian side of the Alps.

The ascent of Aorangi is evidently a long, difficult, and even dangerous excursion. The route is quite as circuitous as that formerly followed in the ascent of the Bernina ; for the great ice-fall of the Hochstetter glacier, 4000 feet high, has to be turned, and another glacier basin crossed, before beginning the steep ascent of the actual peak. Mr. Green's party was forced to turn back without actually touching the culminating point, though they had overcome all difficulties, for the short half-hour which the completion of the excursion would have required might have made return impossible. As it was, they were benighted among the glaciers. Mr. Mannering and his friend, after five attempts, reached a point about 100 feet below where Mr. Green halted, was compelled to turn back for the same reason, and had a dangerous descent over the snow-fields in the darkness. But as an Alpine Club was founded a few months since in New Zealand, there will probably not be many peaks to climb or passes to discover when another decade has passed.

Mountaineering in New Zealand is not for climbers fond of luxury. Guides and porters are at present unknown. Mr. Mannering and his companions had to carry their own swag"-and heavy loads these were -cut their own steps, do everything and discover everything for themselves, for they were self-taught mountaineers. Sometimes he had only one companion, and then the labour and the danger were alike increased. The weather also seems to be more unsettled than it is in the Alps. The rainfall is heavy-150 inches in some places. Thus fresh snow often adds to the difficulties and the dangers of excursions, and falls of stones seem common, as might be expected. Mr. Mannering tells most pleasantly and unaffectedly a story of pluck, endurance, and skill, of which our kinsmen in New Zealand may be justly proud. He is a careful observer of Nature, and a true lover of mountain scenery, as well as a daring climber. His book contains a number of illustrations, taken from photographs, which show that the peak and glacier scenery of the Aorangi group is worthy of the author's enthusiastic praise; and it is not only very pleasant reading, but also adds much to our knowledge of the region. It may be added that, if the traveller is not satisfied with the perils of rocks and snow, those of flooded rivers are a common experience; and Mr. Mannering, in his final chapter, describes the doubtful pleasures of a canoe voyage down the Waitaki River. T. G. BONNEY.

OUR BOOK shelf.

Manual of the Science of Religion. By P. D. Chantpie de la Saussaye. Translated by Beatrice S. Colyer Fergusson. (London: Longmans, 1891.) THOUGH the title of this volume seems to imply that it is a complete thing, it is really only the first half of Prof. de la Saussaye's book. Nearly three-fourths of the Amsterdam Professor's manual is devoted to a sketch of the chief ethnic religions and of Islam; whereas the English

book, corresponding as it does to the first of the two German_volumes, omits the ancient religions of Persia, Greece, Rome, and Germany, as well as Mohammedanism. Without these we have nothing that can fairly be called by the name borne on the title of the translation; and the omission of Persia in particular makes the book most tantalizingly imperfect as regards a single connected group of faiths. It is not fair either to the author or to his readers to give a part of the work as if it were a whole, and to set it forth to the world without even putting "vol. i." on the title-page.

The work of translation has been performed with care, and generally, so far as we have been able to test it, with accuracy. But the book is rather heavy reading, as translations from the German are apt to be, when the translator has not realized that the difference between the idioms of England and Germany is so great that a successful version must recast whole sentences instead of aiming at a literal reproduction of words and clauses. As regards the substance of the book, the reception which it has obtained, in its German form, is a sufficient proof that Prof. de la Saussaye has met a felt want in the literature of his subject. A book that covers so wide a field cannot be without errors in detail. No man can know at first hand all the ancient literatures that are dealt with; nor can it be supposed that, on matters where specialists are often at variance, one who is not a specialist can always hit the mark. The general principles of the science of religion are not yet worked out with sufficient clearness to give the student of religions in general sure points of view for the criticism of the divergent results that have been reached by students of special religious literatures. Perhaps to say this is to say by implication that a general manual of the subject is an undertaking for which the time is not yet ripe; and certainly the science of religion (as distinct from the scientific study of individual religions in their historical development) is still in a very elementary stage. But Prof. de la Saussaye is no dogmatist; he frankly admits the obscurity in which many fundamental problems are still involved, and he writes throughout with great impartiality and moderation, as well as with extensive knowledge of recent researches. His book will be very useful to all who wish to know the present state of inquiry, and do not forget that many things in his exposition are to be taken as still doubtful, even where the author himself does not expressly accompany them with notes of uncertainty.

W. R. S.

Of all Euclid's books, the eleventh is one that forms a stumbling-block to the beginner in solid geometry. Not that the proofs in themselves are of a difficult nature, but simply that the figures have to be drawn perspectively to illustrate the various planes, and the student finds it hard to bring himself to believe the equality of angles and lines which appear to him to be unequal.

The author of this book, like one or two others before him, by varying the thickness of the lines used in construction, simplifies matters very considerably, for by this means the eye can distinguish directly the different planes. Of the propositions themselves, little need be said, unless we mention the use throughout of all the well-known symbols: the occasional interpolated worked-out examples, and the notes and exercises, although not in any great quantity, will be found very useful. In the collection of miscellaneous examples, theorems relating to tetrahedrons, pyramids, spheres, &c., are included. Preceding the series of examination-papers, which are here arranged in a progressive order of difficulty, and taken from papers set lately, are two appendices, the first deal

Illustrations of the Flora of Japan, to serve as an Atlas to the Nippon-Shokubutsushi. By Tomitarò Makino. (Tokyo, Japan: Keigyōsha 1, Urazimbōchō, 1891.) THIS is a monthly publication, containing excellent uncoloured figures of plants, with analyses of their floral structure, fruit, and seed, and descriptions in English as well as in Japanese. The drawing and lithography, by Mr. Makino himself, are quite equal to the average work in this country-indeed, one might say above the average; the lithography being light and effective, with few lines in it. Moreover, the English descriptions are intelligible, correct, and idiomatic, and not too long, nor superfluous. Botanically and horticulturally this production of the Far East will be welcome, and even indispensable, in the West, as many new species are described. Already nine parts have appeared, with illustrations of fifty-seven species belonging to various natural orders. No system of classification is followed; whatever is of interest or novel being taken as it presents itself. W. B. H.

About Ceylon and Borneo. By Walter J. Clutterbuck, F.R.G.S. (London: Longmans, Green, and Co., 1891.) IN this volume Mr. Clutterbuck gives some account of Ceylon as he saw it during a recent visit, and as it was fourteen years ago, when he resided for a short time in the island.

He then describes what he saw in the course

of a visit to Brunei and British North Borneo. Readers who like books of travel will find a good deal to interest them in the author's impressions, which are recorded in a lively style.

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.]

Wind Direction.

A SHORT time ago there was some correspondence in your columns on the relations of north-east and south-west winds in recent years; Mr. Prince, of Crowborough, having observed at that place that while, as a rule, the south-west winds were in excess of the north-east, the reverse had occurred in each of the five years 1885 to 1889. The Greenwich records were examined by Mr. Ellis with regard to this point, but he found them at variance with those of Crowborough, the south-west winds having continued in excess of the north-east throughout those five years.

By combining several directions, the Greenwich figures, as tabulated by Mr. Ellis in his paper to the Royal Meteorological Society (Quart. Journ., October 1890, p. 222), will be found to reveal some curious relations, which seem to invite attention. I have added together the figures (numbers of days) for northeast, east, and south-east winds on the one hand, and those for north-west, west, and south-west on the other; then smoothed each set of sums by means of five-year averages. The results are shown in the two curves of the accompanying diagram. The continuous curve (a) represents north-east, east, and southeast winds (and its vertical scale is at the left). The dotted line curve (b) represents north-west, west, and south-west winds (and

its vertical scale is at the right). It will be understood that each year-point of those curves represents an average of five years.

It would appear that easterly winds (north-east, east, and south-east) at Greenwich have been increasing in prevalence, on the whole, since about 1865; the five years' average for that year is 83.8, and this grows to 1114 in 1886 (about one-third). On the other hand, westerly winds (north-west, west, and southwest) have diminished, on the whole, since 1861; the five years' average for that year is 2108, and this diminishes to 159'0 in 1887 (about one-fourth).

Judging by the past, we might perhaps consider that we must be near a decided turn of the curves; possibly past it in the case of easterly winds; in which case we should look for more westerly and less easterly wind in the near future.

1885 157

From the "crest" of (a) in 1857 to the last point is thirty years. Are those long variations possibly a manifestation of the thirty-five years' period of Brueckner?

These curves might have begun at an earlier date, for the figures commence in 1841. But in the earlier years, and apparently to about 1855, a larger proportion of days seem to have been reckoned as "calms" than afterwards (owing to a difference of rule), so that the curves to about 1855 are not exactly comparable with the remaining portions.

I append a few figures, showing the derivation of maximum and minimum (or low point) averages :

The Migration of the Lemming.

My attention having recently been drawn to the question of the migration of that little Norwegian rodent the lemming, as a serious obstacle to the theory of natural selection, and hence to evolution generally, I write to call attention to what appears to me to be a possible factor in the starting of the migration.

It is that when the lemmings become too numerous for the means of subsistence upon the inland plateaux, which may be described as their home, the "fittest" lemmings, by battle. turn out from the district all those of their weaker brethren who are unable to withstand the contest.

The unfittest being thus driven out from their home, are Why they move incessantly to forced to migrate somewhere. the westward seems a problem yet to be satisfactorily solved.

My reason for suggesting such an origin for the migration is that it takes place every three or four years from the same plateaux. It is very evident, therefore, that-abiogenesis being now out of court-some lemmings must be left there to continue the species. Now, it is not likely that the weakest are left behind, otherwise their survival year after year would be quite problematical. Do not the facts point unquestionably to the strongest being left to continue the race?

To the criticism that there is no evidence of fighting having taken place amongst the migrants, my reply would be that no one, so far as I can learn, has seen a migration start, or seen one immediately after it has started-the only time, that is, when the effects of such fighting would be apparent, for after a few days those seriously injured would have died and have been left behind, while those only slightly injured would have recovered sufficiently to be indistinguishable from the remainder. . Churchfield, Edgbaston. F. HOWARD COLLINS.

The New Railway from Upminster to Romford, Essex, On the above railway, now being constructed, there is a section of unusual interest a few yards north-east of the church at Hornchurch, showing the Chalky Boulder Clay (15 feet seen) under sand and gravel belonging to the highest terrace of the Thames Valley, and resting on London Clay. Hitherto, Boulder Clay has not been seen in this district in connection with Thames Valley deposits, its most southerly exposures lying about three miles northward, on London Clay or Bagshot Beds. I have been carefully watching this cutting for some time, with a view of sending an account of it to the Geological Society when it shall have been completely excavated. But, though much has still to be done, the half of it finished has already been sloped, and the arrangement of the beds--clear a month ago-greatly obscured. It has therefore been suggested to me that a few lines on the subject in NATURE may be the means of enabling geologists interested to visit this section while the Boulder Clay is still clearly visible in some portion of the cutting.

It may be useful to add that the distance from Hornchurch Station is about a mile, and that the visitor, after leaving the church on his right hand, should take the first road on his left. T. V. HOLMES.

28 Croom's Hill, Greenwich Park, S. E.,

December 7.

Peculiar Eyes.

THE inability of keeping one eye shut and the other open at the same time, is a fact well known to drill-sergeants. I well remember, when a conscript some sixteen years ago, how a great number of recruits were unable, even after repeated efforts, to do so; but I had no difficulty about it. At that time, too, my eyes were about equal in power; but at present while the right eye is of normal power, the left eye presents a much less distinct image. I can only ascribe this to the habit of working at the microscope with the right eye without closing the left. It is especially at this work that the defective sight in the latter is noticeable. I do not think my ten months of rifle practice has anything to do with it, except, perhaps, in emphasizing the tendency to use the right eye, the image of which is now so predominant, that in covering a bull's eye, for in-tance, it is immaterial whether the left eye be closed or not.

G. K. GUDE.

5 Giesbach Road, Upper Holloway, December 7.

Grafted Plants.

REFERRING to Prof. Henslow's paper on "A Theory of Heredity based on Forces" (November 26, p. 93), the behaviour of grafted plants seems to require, for its explanation, the possession by both stock and graft of something analogous to a distinct individuality, call it what we may. It is difficult enough to understand, especially in the case of nearly-related forms, why the stock generally has no, or so little, influence on the graft; but, assuming the absence of individuality. the difficulty is largely increased. The graft takes its nourishment through the stock, and yet retains its characteristics unimpaired. I argue from this that not only does the graft possess an individuality of its own, but that this is so marked that it can take its nourishment direct from the stock, while at the same time straining out,

as it were, whatever it is that constitutes the individuality of the stock. The phenomena presented by parasitic plants seem to bear out this view. W. H. BEEBY.

Intelligence in Birds.

A FEW weeks ago I received a specimen of Podoces panderi, the typical desert bird of Central Asia, which had been kept for some months in captivity at Perowsk. The first thing the creature began to do, when located by me in a spacious volière, was to pick some food (cooked rice with baked eggs), and to bury it in the very thick sand layer with which the floor of the cage was provided. This was the incessant occupation of the bird on the first day of its instalment. But the task was almost completely abandoned from the next day; the bird, evidently remembering the conditions of its former life in captivity, found it useless to make provision for the future when a fresh supply of food daily appeared.

The fact referred to seems to indicate, first, that the birds in question are in the habit of making provision in the wild state, the powerful and slightly curved bill being admirably adapted for the purpose of making holes, even in a hard ground. It shows, also, how abruptly the habits of animals can be modified when the conditions of their environment are changed.

Now, a question naturally arises, How must we regard this habit of burying food-as the result of a long inheritance, or as an effect of constant imitation of older birds by younger ones? A. WILKINS.

Tashkend, Central Asia, November 8/20.

TH

SIR ANDREW CROMBIE RAMSAY. HOUGH this illustrious geologist has been laid aside by growing infirmity for the last ten years, the news of his death will carry regret into the hearts of many men of science, not in this country only but all over the world. Born in Glasgow, and intended for a mercantile profession there, he spent some few years in business; but, partly on account of delicate health, betook himself for rest and open-air exercise to the island of Arran. One of the friends of his early years, Prof. Nichol, of Glasgow University, the well-known writer on astronomical subjects, had much influence in directing his studies into a scientific channel, so that the marvellous geological lessons to be learnt from the rocks of Arran soon arrested Ramsay's attention. Throwing himself with all the ardour of an enthusiastic nature into the pursuit which he now took up, he was led to climb the mountains and traverse the glens throughout the length and breadth of Arran. In this way, face to face with the facts of Nature, and amid some of the most charming scenery of his native country, he taught himself the rudiments of geology, and acquired that clearness of insight for geological structure, that love of mountain-forms, and that freshness and originality of interpretation, which marked him out from his associates in later years. But above all, by actually mapping the grouping of the rocks, he gained that pre

cision in field-work which was to bear such notable fruit in his connection with the Geological Survey. He constructed a geological model of Arian on the scale of two inches to a mile, and made copious notes of the geological structure of all parts of the island.

The meeting of the British Association in Glasgow in the year 1840 proved to be the turning-point in his career. The model and map of Arran which he had made were exhibited at the Geological Section, and he gave a brief account of them and of the geology of the island. Among the geologists who listened to him was Murchison, who, struck with his ability and his devotion to the science, offered to take him on an expedition which the author of the "Silurian System" had then projected to America. Ramsay accordingly went up to London, but found that the voyage across the Atlantic had been abandoned for a journey into Russia, and that he was not to take part in it. Murchison, however, spoke so warmly in favour of his

young friend to Sir Henry De la Beche, the DirectorGeneral of the Geological Survey, that a post was at once found for him on the staff of the Survey, and before many days Ramsay was at work at Tenby. He joined the service in the spring of 1841, immediately after the publication of the little volume on Arran, which embodied the fruits of his labours in previous years. From that time onward his life was spent continuously in the work of the Survey until he retired at the end of 1881. So capable a lieutenant did he prove himself to the chief of the staff, that after only four years he was appointed Local Director for Great Britain.

From the first Ramsay showed that, with habits of patient observation and cautious induction, he combined a faculty for bold and broad generalization. His remarkable paper on the denudation of South Wales, published in 1846, was one of the earliest essays in which the amount and effects of denudation were worked out from detailed surveys of the geological structure of the ground. He then struck the key-note which may be heard through nearly all his subsequent contributions to scientific litera

ture.

He was one of the earliest observers to realize that the existing topography of the land has a long and interesting history, much of which may still be deciphered by the use of geological investigation.

The name of A. C. Ramsay will ever be honourably associated with the story of the gradual working out of the records of the Ice Age. Following up the results obtained by Agassiz, Buckland, Darwin, and others in this country, he threw himself with all his ardour into the study of the glaciation of Wales, tracing the limits of the glaciers of that region, and extending his expeperience by frequent excursions among the Swiss Alps. His scattered papers in scientific journals undoubtedly did much to stimulate general interest in the history of the Glacial Period, and to create a special and voluminous literature of this subject. His views differed much from those of some of the older geologists of the day, and led to some active controversy. Especially did opposition arise when, after studying long and carefully the erosive action of land-ice, he came to the conclusion that certain lake-basins in various parts of the world had been scooped out by ice. Murchison, Lyell, and others of less fame, entered the lists against him; but he had a considerable following among the younger geologists. And this controversy still fitfully continues.

In connection with his glacial work, mention should be made of his bold endeavour to prove that ice-action had been in operation more than once in the geological past. His paper on the Permian breccias of England called attention to the evidence of transport of fragments of rock from Wales, and to the resemblance between these fragments and those in glacial moraines and boulder-clay. He subsequently detected what he thought to be similar traces of ice-carried materials in the Old Red Sandstone; and in one of the last papers which he wrote he gathered together the various pieces of evidence in favour of a long succession of Glacial periods in the geological past.

the leading part, will ever remain the best monument of his skill as a field-geologist. His exhaustive memoir on that region has long since taken its place as one of the standard works of reference in our geological literature. In his later years he seems to have taken pleasure in reverting to some of the inquiries which he started in an early part of his career. He returned with renewed zest to the study of the history of topographical features, discoursed as to how Anglesey became an island, and traced out the story of the River Dee. In successive editions of the work on the "Physical Geography and Geology of Great Britain," which at first was given as six lectures to an audience of working men, he worked out in greater fulness the chief stages through which the surface of this country seemed to him to have passed before it acquired its present features.

Of the value of his scientific labours full recognition was made by his contemporaries. He was elected President of the Geological Society in 1862, President of the Geological Section of the British Association in 1866 and again in 1881, and President of the Association itself in 1880, when the meeting was held at Swansea. He received the Wollaston Medal of the Geological Society, the Neill Medal of the Royal Society of Edinburgh, and a Royal Medal from the Royal Society. He was chosen into the honorary list of many learned Societies at home and abroad. On the death of Sir Roderick Murchison in 1871, he was appointed Director-General of the Geological Survey. At the end of 1881 he resigned this office, was knighted for his distinguished services, and soon thereafter went to reside at Beaumaris, where his strength has gradually given way, until he died on the evening of the 9th inst.

There was in Sir Andrew Ramsay such simplicity and frankness that men of the most diverse natures were attracted to him, and as they came to know him more intimately the gaiety and kind-heartedness of his disposition attached them to him in the closest friendship. Fond of literature, and glad to relieve the pressure of bis scientific work by excursions into the literary field, he had acquired a range of knowledge and of taste which gave a special interest to his conversation. Now and then he found time to write an article for the Saturday Review in which this literary side of his nature would find scope for its exercise. But the daily grind of the official treadmill left him all too little time for such diversions. His death removes from our midst one of the foremost geologists of our day, and from the friends who knew him in his prime, a large-hearted, lovable man, whose memory they will cherish till they too pass away. A. G.

ON VAN DER WAALS'S ISOTHERMAL
EQUATION1

ΟΝ
NE of the objections raised against this equation by
Prof Tait in NATURE, vol. xliv. pp. 546 and 627,
brings clearly to light the importance of the question
whether the finite size of the particles should be accounted
for by an equation of the form-

where

11(v b) = mu3,.. ... (1) represents the internal pressure, equal to the sum of the external pression p, and the molecular pressure and some multiple of the total volume 6, of the particles; or if this equation must rather have the formb

(2)

Prof. Korteweg's paper and accompanying letter are of date November 4, but owing to an accidental delay they did not reach me until after the appearance of my last communication (NATURE, November 26, p. 80). Other wise I should, of course, have made reference to them. It will be seen that Prof. Korteweg draws attention to the form of the virial equation applicable in one dimension. RAYLEIGH

December 2.