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the heated face tends to retreat with a force propor- was undertaken in 1897-8. Mr. Beadnell carried out tional both to the density of the gas and to the area the mapping of the Farafra and Dakhla oases, while of the surface.

Dr. Ball was engaged in surveying that of Kharga, A calculation of the absolute value of the excess of the work in the Baharia Oasis being shared between pressure cannot be made without further hypothesis. the two investigators. Dr. Ball's map of the Kharga If we were to suppose that the molecules, after col- Oasis, with the accompanying official report, is a lision with the heated face, rebound with the same work of great geological value and interest, and Mr. velocities (v+dv) as they would have were the tempera- Beadnell's residence in the district has enabled him to ture raised throughout, the pressure would be in- add not a few important scientific details to the creased in the ratio v+(v+dv): 2v or i+dv /2V : 1.

admirable sketch given by his colleague. On the other hand, if the temperature were actually The whole Libyan Desert forms a plateau, having raised throughout, the pressure, according to the usual an elevation which, at its maximum, is but little less gaseous, laws, would be increased in the ratio than 2000 feet above sea-level, yet with a fairly general (v+dv)? : v2 or 1+2dv/v: 1. On this hypothesis, there- slope towards the north. In this great expanse of fore, the unbalanced increment of pressure on the rough limestone and flint-covered flats, with heated face is one-quarter of the increment that would hillocks and troughs of drifting sand, the oases are be caused by a general rise of temperature to the deep depressions, the bottoms of which vary from same amount. This estimate is necessarily in excess 100 to 300 feet above sea-level, surrounded, for the of the truth, but it is probably of the right order of most part, by steep escarpments, through which only magnitude.

a few passes can be found which are capable of being The supposition upon which our reasoning has been used as camel-tracks. The whole of the deserts are based, viz. that the mean free path of a molecule is underlain by great beds of sandstone (the Nubian large in comparison with the linear dimension of the series), forming two divisions, the “surface-water vessel, has been made for the sake of simplicity, and sandstones," never more than 160 feet thick, separated is certainly a very extreme one. It is not difficult to by 250 feet of impervious grey shales, from a much recognise that in the extreme form it may be dispensed thicker series of sandstones below, the artesiarwith. All that is really necessary to justify our con- water sandstone,” which has been penetrated by clusions is that the mean free path should be very borings to the depth of 400 feet. large in comparison with the vane. The magnitude It is by the removal, through denudation, of great and distribution of the velocities with which the masses of Eocene and Upper Cretaceous limestones molecules impinge will then be independent of the and shales that the “surface-water sandstones " have fact that the face of the vane is heated, and this is been exposed on the floors of the oases. These beds all that the argument requires. The repulsion by are the source of springs, and, since the districts have heat of a silk fibre suspended in a moderately rare been occupied by human beings, a great part of the gas was, it will be remembered, verified by 0. area of the Kharga Oasis was covered by shallow Reynolds.

RAYLEIGH. lakes, probably formed by the outflow from these

springs. But these great lakes have been gradually

dried up, and the constant drain on the limited supplies LIFE IN AN OASIS.1

of water afforded by the “surface-water sandstones” ΑΙ

LTHOUGH the oases of the Libyan Desert have has greatly reduced its importance as a means of

been frequently visited by travellers-Poncet in | irrigation. The accounts of the various deposits laid the seventeenth century, Browne in the eighteenth | down in these old lakes, with their interesting concentury, and Cailliaud, Drovetti, Edmonstone, tents of worked flint-nakes and pottery, are among Hoskins, Rohlfs, Zittel, Schweinfurth, Brugsch, and the most novel and interesting portions of Mr. others in the nineteenth century-yet none of these Beadnell's book. authors enjoyed anything like the opportunities far more important, however, than the surface. for the study of these remarkable districts which have water sandstones, as a source of irrigation water, fallen to the lot of the writer of the work before us. the “artesian-water sandstones, which, by For nine years Mr. Beadnell, as a member of that means of borings, have been drawn upon from the active body the Egyptian Geological Survey, was earliest times, and constitutę even now a practically engaged in the study of the Libyan Desert-including inexhaustible means for promoting the cultivation of the four cases of Baharia, Farafra, Dakhla, and the oases. On all questions connected with the nature Kharga—while during the last three years, as director and amount of the yield of the different kinds of of the operations of a development company, he has wells, the author of this book writes as an authority, resided in the last mentioned, and has carried out and he is able to give the results of numerous inimportant observations and experiments in connection genious experiments, carried on, in some instances, for with the questions of water supply, the effects of many months. That the enormous quantities of water moving masses of sand in increasing the fertility of contained in the thick sandstones of the Nubian some areas, while overwhelming and destroying svstem have their source, in part in the highlands of others, as well as of many other problems of great Abyssinia, in part in the Sudan, and to some extent historical and antiquarian interest.

in the upper waters of the Nile, where it flows over Now that the opening of a railway from Qena, a these pervious sandstones, there can be little doubt, little north of Luxor, to the village of Kharga has though as to the proportional parts played by these been completed, the long and tedious camel-journey of several factors of the supply there is still much room four or five days along very rough caravan routes is for doubt-a doubt which can only be removed by avoided, and excursions from the Nile valley to this prolonged observations. typical oasis will doubtless become much more fre- The manner in which the ancient wells have been quent. The appearance of the present work is, there- made, kept open, and from time to time repaired, has fore, very opportune. The detailed topographical and engaged the author's attentive study. It is surprising geological survey of the Libyan Desert with its oases to learn how much has been accomplished with the

1 "An Egyptian Oasis: an Account of the Oasis of Kharga in the Libyan aid of very simple appliances; and the long subDesert, with special reference to its History, Physical Geography, and terranean aqueducts—tunnels driven for miles into Water Supply." By H. J. Llewellyn Beadnell. Pp. x+248.; with 28 plates and 4 maps and sections. (London: John Murray, 1909.) Price 1os. 6d.

the sandstones for the purpose of increasing the flow

of water-with numerous manholes up to the surface,

are

net.

are wonderful monuments of persevering toil. The Persian rule, Cambyses sent an ill-equipped expedition introduction of modern boring machines and other to conquer the oases, but the whole army of 50,000 labour-saving contrivances may probably do much men, probably through the treachery of guides, towards increasing the productiveness of the land of perished miserably in the desert. The Romans long these oases in the future. Very interesting informa- held sway in the oases, and many of the most retion is given concerning the cultivation carried on in markable of the monuments of the district must be the Kharga Oasis, and its possible extension in the referred to the period of their rule. The work before future. The chief crops at present are rice, date and us indicates the great numbers of objects of archæodoum palms, and lucerne, though grapes, oranges, logical interest which are found in the district, and other fruits are produced to a small extent. Many including many Græco-Roman temples and a wonof these fruits, with cotton and other useful vegetable derful early-Christian necropolis, as well as very early products, may be largely supplied from these districts, now that communication has been im. proved by the construction of the railway. In spite of the traditions concerning the existence of deposits of gold, silver, and other metals in the oases, it is probable, considering the geological structure of the district, that it is never likely to yield mineral pro. ducts of greater value than the ochre, alum, and epsom salts, which the ancients obtained in small quantities as the result of an altogether disproportionate expenditure of labour and pains.

The author, being evidently, a keen sportsman, is able to give many interesting details concerning the feral life in these singular depressions of the desert. The wild mammals consist of the Dorcas gazelle, with three species of fox, and occasional striped hyænas and jackals; the birds, of sand-grouse, 'rock-pigeons, turtledoves, and quail. But British sportsmen must be prepared to find, among the primitive inhabitants of these lands, competing sportsmen, as enthusiastic and probably more experienced and persevering than themselves.

Although it is to the questions of water supply, and the dependent problem of agricultural development, that we look mainly for information to this work, yet its author has not been unmindful of many other points of general interest concerning the population of 8000 to 9000 souls and its distribution. They belong to Berber tribes, quite distinct from the fellahin of the Nile Valley, but with admixture from various other sources, and the author has been able, during his sojourn among them,

Encroachment of Sand-dunes at Meherig. From "An Egyptian Oasis." to learn much that is of interest about their habits and customs. Their flint implements and pottery. We learn that Mr. personal characteristics, peculiarities of land- and Pierpont Morgan has already had explorations comwater-tenure, their taxation and commercial methods menced for the enrichment of American museums, are well described, and the features of their villages and the completion of the railway may not improbably and farms are admirably illustrated. Their modes of lead to excursions to Kharga and its temples

' becomcombating their great enemy the drifting sands from ing as popular as the trips to the cataracts and the north, which tend to form ever-advancing sand- | temples of the Nile are now. The book before us, dunes, receive especial attention. Some of the results which is dedicated to the memory of an old colleague attending this constant sand-drift are illustrated in the of the author, Mr. Thomas Barrow, who fell a victim figures taken from the work.

to the climate during explorations in the Sudan, ought The Egyptian kings, certainly from as far back as to help to make known the points of interest atthe eighteenth dynasty (1545-1350 B.C.), have claimed taching to these wonderful depressions in the great dominion over these cases. When Egypt fell under Sahara.

JOHN W. JUDD.

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THE ISLE OF WIGHT.2

realising the difficult task that I was undertaking ";

and he expresses himself content to have served as a find, along a coast line of only sixty miles, so after him are enabled to profit by his mistakes of

can many varied and magnificent cliff sections of the omission and commission. Such modesty disarms Cretaceous and Tertiary formations, and in no British criticism, and Mr. Morey's energy and enterprise area of equal size-a hundred and sixty square miles, deserve the warm thanks and congratulations of all can the botanist collect so many species of flowering who are interested in the natural history of the Isle of plants, as in the “ Garden Isle,” which has long been Wight. a happy hunting-ground for field naturalists. Its rich As is the case with all compilations, the book is flora and fauna, conditioned largely by its diversified unequal in quality, but we feel bound to point out soil, has already been dealt with in various works, two defects which, though common enough in works notably in Venables' “ Guide to the Isle of Wight of this kind, detract considerably from its value and (1860), and in the Hampshire section of the “Victoria interest. County History” series.

A book which attempts to compress into a comThis new "Guide" contains a large number of paratively small space an enumeration of the entire

[graphic]

Photc.)

(H. F. Poole. Fig. 1.--The Culver Cliffs : Inset showing Herring Gulls at their Nests. From " A Guide to the Nat :ra! History of the Isle of Wight."

new records, and will at least form a good basis upon fauna and flora of a rich district, with an account of which resident and visiting naturalists may build a its geology, to say nothing of articles on palæolithic complete natural history of the district. There can be implements, meteorology, and even earthquakes, must no question as to Mr. Morey's qualifications for the necessarily consist largely of a census catalogue of editorship of this volume, since he has worked at the species. Lists of species are undeniably useful, and fauna and flora of the island for forty years, and in not to be despised when compiled carefully, but the producing the “Guide” has obtained the services of ideal to be aimed at in a real natural history is surely a capable band of systematists in the various branches something that shall go beyond, and in some respects tealt with. One cannot but admire his industry, be the antithesis of, a mere list. Beyond a few.vague versatility, and enthusiasın. He tells us, “when, references to the bare fact that the distribution of nearly three years ago, I decided to bring out a work species of flowering plants, mosses, &c., is affected which should fairly illustrate the fauna and flora and by the characters of rocks and soils, we look in vain the natural history generally of the Isle of Wight, 1 for any evidence of the scientific ecological spirit which did so, almost literally, with fear and trembling, fully animates such works as Baker's “ North Yorkshire,'

1 "A Guide to the Natural History of the Isle of Wight.” A Series of Lees' “West Yorkshire," and Wheldon and Wilson's Contributions by Specialists, relating to the various branches of Natural “ West Lancashire," and has made them valuable History and kindred subjects. Edited by Frank Morey. Pp: xx+560: contributions to the growing literature of plant (Newport, 1.w.: County Press; London: W. Wesley and Son, 1909.) | ecology. The three books cited are, of course, limited

net

to the botany of each district, but a general sketch of string of incoherent and inaccurate sentences, repeatthe distribution of the flowering plants, at any rate, ing and perpetuating long since exploded errors and should have been given in this Guide." The island mare's-nests. Lichenologists, we know, are a stiffwould afford excellent scope for a botanical survey, on necked generation, but surely it is time they hesitated the lines of the well-known work done by Dr. Smith, to record in print their refusal to recognise the dual Dr. Moss, and other ecologists, in various parts of nature of the lichen thallus, which has been fully and Britain. It is greatly to be hoped that in a future finally established. There can be no excuse, either, for edition of, or supplement to, this “ Guide" it will be the hepaticologist who tells us that the liverworts are found possible to include a chapter on plant distribu- “ linked to the lichens” by means of their thalloid tion, with a vegetation map of the island, and, for forms! The account of the relationship between the comparison and correlation, a geological map. This liverwort Frullania and the rotifer which sometimes would, if carefully done, preferably by an ecologically occupies its pitchers is entirely imaginative. The list minded botanist residing in the district, undoubtedly of hepatics (liverworts) is conspicuous by the omission enhance the value of the book and secure for it more of several species which are certainly found in the than the local interest that attaches to a merely island, and often abundantly in places, such as Anthofloristic work.

ceros laevis, Scapania nemorosa, and Lepidocia reptans.

The articles by Mr. G. W. Colenutt (geology), Mr. P. Wadham (fishes, mammals, &c.), and Mr. R. H. Fox (birds) stand out as refreshing oases in the arid desert of species lists, being written in a “naturestudy" spirit which can hardly be said to characterise the work of the other contributors. The “ Guide " is illustrated by twenty-six excellent plates, chiefly from photographs by Mr. H. F. Poole, two of which we are permitted to reproduce here.

F. C.

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SLEEPING SICKNESS.
I

T may be taken as definitely established that sleep(Trypanosoma gambiense), and that this trypanosome is conveyed by a tsetse-fly (Glossina palpalis). But if we proceed to analyse and extend this proposition we soon get into difficulties. We do not know for certain whether man is the only “reservoir " of this trypanosome, or whether monkeys and other mammals, especially native dogs, can also harbour it. Should this prove to be so-though the balance of evidence is against the supposition-it must materially affect prophylactic measures. If we consider next the mode by which the trypanosome is conveyed we find ourselves in the midst of the most conflicting evidence. It is still uncertain whether the transmission is mechanical or whether there is a cycle of development 2 of the trypanosome in the fly; facts appear to be all in favour of the first view, analogy all in favour of the latter. Nor is the question a. purely academical one, for if the transmission is mechanical, then the flies are no longer infective after the infecting reservoir (man) is removed; if, however, there is a cycle of development, then it remains to be determined how long an infected fly can remain infective after the infecting source is removed.

If, again, we consider the question, Can sleeping Photo.)

(H. F. Poole.

sickness be conveyed by any other species of tsetseFig. 2.-White Stork-a rare visitor-captured at Shorwell in 1902. From fly than Gl. palpalis ? we must confess our ignorance. “A Guide to the Natural History of the Isle of Wight."

The balance of evidence certainly seems to be against

the possibility, but should it be shown that other The second suggestion we venture to make, with species can convey the disease, then the question of reference generally to books similar in scope to this prophylaxis would be even more difficult than it now “Guide,”' is that most of the systematists responsible is. These reports show that these are some of the for the various lists of plants and animals given in questions that urgently need solution, but there are local naturalistic compilations would do well to obtain others of equal importance which arise in the immethe cooperation of a biological botanist or zoologist diate carrying out of prophylactic measures. They when writing their prefatory remarks on the group concern the Ay itself, its habits, duration of its life, of plants or animals they are dealing with.. So far its breeding grounds, its food, its powers of flight, its as this "Guide" is concerned, we refer chiefly, as likes and dislikes in regard to foliage, trees, shrubs, examples, to the sections dealing with some of the grass, &c. These questions are all important, and cryptogamic plants. It would be far better for the average cryptogamic systematist to pass straight on 1 "Reports of the Sleeping Sickness Cɔmmission of the Royal Society." to his list and say nothing whatever about the life- No. ix.

? The existence of such a cycle is now practically established by the history and development of his group than to write a recent work of Kleine confirmed by Bruce.

in our opinion it is imperative to appoint one or more important to note that such areas are numerous, and officers with special entomological knowledge to study may often be only a few hundred yards away, Fresh these points minutely. It is true that these reports infection of the Hy is also avoided by preventing the afford evidence that the officers concerned in these removal of infected natives to uninfected fly areas. investigations have made additions to our knowledge The applicability of this measure depends mainly upon on these points, but the other duties of these officers the “attitude" of the native. are so multifarious that valuable time is being lost (3) Measures directed against the trypanosome itself, through this defect. It is true also that in the i.e. the treatment of infected persons, are bound up epidemic in Uganda the condition of things is so closely with the segregation of the sick. The treai. terrible that it is impossible to wait for the solution ment of the segregated in fly-free areas by atoxyl or of all these questions, however important, before other arsenic preparations is the only one that is at any action is taken, and we may now consider what, all effective, but it must be admitted that the results with the present available knowledge, is being done are disappointing, and that the good results of the to check the epidemic. The means of prophylaxis may drug are in many cases only temporary. The patient's be considered under three aspects :-(1) Those directed blood becomes free from trypanosomes (and presumagainst the fly; (2) those directed against the carrier ably non-infective, though this is not proved), and so of the trypanosome, i.e. man; (3) those directed against the chance of infection of the fly, if patients come in the trypanosome itself.

contact with fly areas, becomes less. (1) With regard to measures directed against the Time will show how far these measures, the fly. It has been found, and it is a matter of the numerous important details of which we have to leave highest .mportance, that the “ natural range of the unconsidered, will be successful. Those engaged in fly, i.e. the distance to which flies follow from water carrying out these arduous and dangerous measures in search of blood, is, as a rule, under 50 yards. The have hope that although sleeping sickness may not be still more important fact has been determined that eradicated or the fly totally annihilated, yet that the clearing and burning or removing the undergrowth epidemic will soon be under control. It must be the for a distance of 100 yards in either direction, e.g. sincere wish of everyone that this hope may be from a ferry for a strip 50-100 yards broad, has justified.

J. W. W. S. the effect of banishing the fly. It is this method, then, i.e. banishing the fly by clearing from its “normal fly range,” that is the basis of the methods now being

THE CONTAMINATION OF MILK. extensively around a village, but simply to clear THE contamination of milk has been the subject comparatively small strips of the “ fly. range " fre- on behalf of the councils of the county boroughs of quented by man,. Although flies may occur in the Bradford, Hull, Leeds, Rotherham and Sheffield, and village itself, unless there is a fly area” present the administrative counties of the East and West these flies are those which have followed their victims Ridings of Yorkshire. Of previous investigations, beyond the " fly range to the village. If the flies Delépine concluded that though his results did not of the “fly range are banished, then, ipso facto, the exclude the possibility of infection at the home of “ following ” flies also disappear. A typical fly area, the consumer, or during transit from the farm, they though there are exceptions, consists of more or less did indicate that infection at the farm, or through open water with contiguous and especially overhang- vessels infected at the farm and used by the farmer ing shade and generally a fairly well-defined bank or

for the storage and carriage of milk, was of parashore. If, then, clearing can permanently banish the

mount importance. On the other hand, Newsholme fly, and we believe that this will be found to be the attaches little importance to infection at the cowcase, because the fly still has plenty of uncleared shed. Dr. Orr's investigation was carried out in a area to frequent—though the fact that its human blood systematic manner, and not only were the bacteriosupply is at the same time removed may modify the logical examinations carefully performed, but, in addiresult—it is an important measure of prophylaxis, tion, the condition of the cows and cowsheds and though its value is perhaps restricted to somewhat the effects of season and atmospheric temperature small areas and special conditions.

were noted. First, the bacterial content of the milk If the fly cannot be removed by clearing, then the l in the udder was estimated, and it was found that population must be deported from the vicinity of the the fore-milk (that first milked) contained from 18,000 to Ay. This measure has been extensively carried out 48,000 microorganisms per cubic centimetre, and the in Uganda by the removal of populations from the milk after the removal of the fore-milk 890 to 4800 per lake to inland fly-free areas two miles away, to prevent cubic centimetre. traffic from the lake, which is responsible for the

It is generally agreed that the milk as secreted is great bulk of the infection; but in many cases there sterile, the microorganisms in the milk as drawn are serious difficulties in the way. Further, the being derived from lodgment and multiplication in removal of populations still non-infected from a poten the teats and cistern. tially dangerous fly area to a safe fly-free area would Dirt on the udder is a fruitful source of contamina. be of the greatest importance, and would form a more

tion, and, during milking, dust, &c., from the udder striking object-lesson to the native of the value of adds much to the bacterial content of the milk. Dust these measures than the removal of an infected popu. in the cowsheds, and the entrance of dirt during lation, because a certain, probably high, percentage transit and delivery, further add to the contamination, of these latter will eventually die of sleeping sickness, so that the milk, when it reaches the consumer, may although in a safe area; whereas this would not be contain an appalling number of microbes. The chief the case if the population removed was non-infected. conclusions derived from Dr. Orr's work are :-

(2) As the two measures, clearing and deportation, of the healthy, are undertaken with the object in view sumer, the greatest number are contributed by the farmer.

(1) Of the total organisms in the milk used by the conof preventing access of the fly to man, so segregation During railway transit, at the retailer's premises, and in of the sick prevents fresh infection of the fly, and

the consumer's house, smaller amounts are added, the diminution of the infectivity of the fly in a fly area. amount in each instance being apparently about the same. This implies the removal of the sick of a village to (2) Of the glucose-fermenting or intestinal organisms another village or camp in a fly-free area, and it is and the streptococci, by far the greatest number are added

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