First Steps in the Calculus. By A. F. van der Heyden. Pp. vi+216. (London: Edward Arnold, 1906.) Price 3s.

THE modest claim expressed by the author in his preface, in the hope "that a step in the right direction has been taken towards producing a text-book suitable for an ordinary class in a Secondary Day School," is a claim which it would be impossible to deny. Experience has shown that geometrical illustrations, such as those on pp. 32-34, 45, and 96, are actually of great help to beginners, and we quite agree with the author that complicated theorems, such as Taylor's expansion (when applied to any but rational integral functions), should not be taken too carly. The introduction (p. 93) of Lodge's treatment of the connection between integration and summation would be good if the step where the assumption is made were clearly pointed out. But there are many points which the author might have considered more fully before issuing the book. While the sine and cosine are properly differentiated, it is surprising to find such a clumsy method employed for the tangent. In order to differentiate a power the beginner is required to swallow the usual series of terms which vanish in the limit, instead of treating the power as a product.

In one or two places, in putting the chord of a curve equal to the corresponding arc, a line of explanation, or even a reference number, would have made things much clearer. The introduction of e as early as chapter vi. is no doubt in accordance with traditions, but it is a pity to defer the study of the calculus until the text-books in algebra referred to for a discussion of exponential series have been read. Rational integral functions, with applications to geometry and physics, afford plenty of material for the beginner. Lastly, the questions in examples ix. are very important indeed, but they give difficulty to many students who can hardly be described as beginners. The general conclusion is that the book would be more correctly described by a title which did not suggest something so very elementary. It is well suited for the class-room.

A Manual of Hydraulics. By R. Busquet. Translated by A. H. Peake. Pp. viii+312. (London : Edward Arnold, 1906.) Price 7s. 6d. net.

THIS book is a translation of a French treatise on hydraulics by Prof. Busquet, of the École industrielle de Lyon. It claims to be a text-book of applied hydraulics in which complete technical theories, and all useful calculations for the erection of hydraulic plant are presented. The translator appears to have done his work well, and to have given the meaning of the author in English terms and phrases. While the same arithmetical methods used in the original have been adhered to, the dimensions have been changed into ordinary British units, and the constants given in the formulæ have been modified to suit the change. The first three chapters deal with the elementary principles of the flow of water in open channels and pipes, and the last chapter with the flow over weirs. These subjects are dealt with in a simple and practical way. They do not, however, contain any inform

ation that is not to be found in English text-books on the same subject.

The fourth chapter, which occupies about half the book, is devoted to the theory and description of hydraulic motors and engines used to transform the energy contained in a head of water into mechanical work. The use of waterfalls hitherto has been limited, because the application of the energy could only be used locally, but since electricity has come into use for the transmission of power to great distances, water has assumed a new and increased value as an economical source for the production of power, and the construction of hydraulic installations is inThe use of water-power creasing at a rapid rate. and the machinery required to adapt it to commercial use have received very little attention from the authors of modern English and American treatises on hydraulics.

The writer does not know of any book that deals with this subject in so practical a way as the one under notice. The several kinds of water-wheels in use are described and illustrated, and their theoretical and useful value demonstrated. Turbines, which are now being largely used for the distribution of waterpower, are freely dealt with, and the merits of the different forms of this machine discussed. The book is calculated to be of service both to students of practical hydraulics and to those engaged in designing and carrying out works for the utilisation of waterpower.

Guide to the Principal Families of Flowering Plants. (After Engler's System.) By J. Adams. Pp. iv+46. (Dublin: Sealy, Bryers and Walker, 1906.) Price Is. net.

A CONVENIENT Summary for determining the orders of flowering plants is a much required desideratum. The difficulties in compiling such a summary are very great, not the least being due to the impossibility of defining the limits in certain cases between allied orders. Mr. Adams has not attempted such details, preferring to leave out a large number of orders and to sacrifice difficult distinctions to brevity and general utility. With regard to the statement that the book is after Engler's system, this applies only to the names of the orders; the method of separation is purely artificial. Thus, in the Archichlamydeæ, parasites and insectivorous plants are first eliminated, then consideration of the vegetative organs provides the next stages in differentiation. So far as practical tests have been applied with a few orders, the tables have given quite satisfactory results.

The Extra Pharmacopoeia of Martindale and Westcott. Revised by Dr. W. Harrison Martindale and W. Wynn Westcott. Twelfth edition. Pp. XXX + 1045. (London: H. K. Lewis, 1906.) Price

IOS. net.

THIS most useful volume has now reached its twelfth edition, and extends to more than a thousand pages. The pages are small ones, but packed with information, and the paper is thin, so the volume still remains one of handy size. The book is more than its name indicates; it not only includes remedial agents which have been introduced up till now into medical practice, but contains a great deal of information regarding recent research in disease. instance, we find an excellent summary of the present state of the cancer question, the newest methods of bacteriological investigation, and a concise statement of modern views on toxins and antitoxins, serum therapy, opsonins, and the like. No busy practitioner can afford to do without such a convenient and trustworthy vade mecum.

For

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 Extirpation of the Tsetse-fly: a Correction and a Suggestion.

IN my letter published in NATURE of October 25 on the breeding haunts of the tsetse-fly discovered by Dr. Bagshawe, I stated that there were no banana plantations ⚫on the deserted island of Kimmi, on the Victoria Nyanza, and suggested that the flies there must have some other breeding-places than the plantations. I am informed, however, by my friend and colleague Lieut. A. C. H. Gray, R.A.M.C., who has just started for Uganda, that he and the late Lieut. F. M. G. Tulloch, when collecting flies on Kimmi, came across deserted banana plantations, overgrown by the forest and bearing ripe bananas (a sure sign that no natives visit them or know of them). I must correct, therefore, my former statement.

If the banana plantations should prove to be the sole or principal breeding-place of the tsetse-fly, the question at once arises, what means could be taken to exterminate the fly or check its increase? To destroy the plantations would be impossible, as I have said, because the banana is the staple food of the country. I venture to suggest that an efficient means of keeping down the tsetse-fly would be to encourage or constrain the natives to keep fowls in their plantations in places where the fly is abundant. These birds would scratch up and discover the pupæ much quicker than a man could, and would probably devour them greedily when found. In forest districts it might be seriously considered whether it would not be advisable to introduce the Indian jungle-fowl for the same purpose. It is, of course, always a risky thing to introduce exotic wild species into a country, but the jungle-fowl, being a valuable game-bird, could hardly be a serious nuisance, however much it multiplied.

I would suggest, further, that a most suitable place in which to try experiments on the extirpation of the fly would be the island of Kimmi already mentioned. Within easy reach of Entebbe, uninhabited, covered with forest or jungle, and swarming with tsetse-flies, it is a locality in which it would be very easy to introduce the junglefowl and to watch the effects. As there are no monkeys, so far as I am aware, on the island, the fowl would probably be able to flourish and multiply unchecked. Such an experiment, even if it failed to produce the desired effect, could do no harm, and if it succeeded would be of very great importance. E. A. MINCHIN.

Lister Institute of Preventive Medicine, November 2.

The Efficiency of the Present Process of Natural Indigo

Manufacture.

IN NATURE of September 20 (vol. lxxiv., p. 526) I find mention of a paper read before Section B at the recent meeting of the British Association by Mr. W. Popplewell Bloxam, on a new method of determining indigotin. It is stated that "the author concludes that the present process of manufacture is a wasteful one, the highest efficiency attained not reaching 50 per cent., whilst on the average only 25 per cent. of the indigotin in the leaves is extracted."

In justice to the indigo-planting community in India, I think this statement should not go unchallenged. The grounds on which Mr. Bloxam draws his conclusion are not given in the brief résumé of his paper in NATURE, and I am therefore obliged to seek an explanation in his communication to the Journal of the Society of Chemical Industry of August 15 on the same subject, in which a similar statement of the low efficiency of the indigo-manufacturing process is made. In this paper Mr. Bloxam gives the analysis obtained by his new method of the indigo turned out each day during the manufacturing season at a certain factory in Bihar. From the figure so obtained, and the total daily outturn of finished indigo recorded in the factory

66

mahai" book, he calculates the amount of indigotin produced day by day, and from the proportion existing between the, amount so calculated and the amount theoretically obtainable, deduced from the weight of green plant placed in the vatand the assumption that this plant contains 0.6 per cent. of indigotin, he arrives at his estimate of the efficiency of the manufacturing process.

Now it is clear that in this method of calculation error may occur in the following particulars :

(1) The analysis of the finished indigo.

(2) The weighment of the daily outturn of finished product.

(3) The weighment of the green plant.

(4) The assumed content of indigotin in the green plant. The first point is one for discussion elsewhere. It is sufficient for my present purpose to point out that the average of Mr. Bloxam's results (60 per cent. indigotin) agrees substantially with the average quality usually his results probably do not differ very widely from the accepted as typical of Bihar indigos, and that, therefore, truth. The same cannot be said of the second point. Separate weighment is hardly ever made of the daily outturn of an indigo factory, and I know as a fact that this was not done in the case on which Mr. Bloxam bases his figures. A rough estimate of the outturn is arrived at by measurement of the cakes produced in a wet condition, and the result obtained generally falls short of the actual production by 10 per cent. to 30 per cent. Mr. Bloxam must therefore have obtained his figures from cake measurement at best a very inaccurate proceeding.

Similar inaccuracies occur in the weighment of the green plant in the ordinary factory routine; but the culminating error on which Mr. Bloxam's figures are based occurs in his assumption of 0.6 per cent. as the amount of indigotin occurring in the green plant. It has been my privilege to serve the indigo planters in Bihar in a scientific capacity for nearly five years. During this time I have carried out some hundreds of analyses of indigo plants of all varieties, ages, and sizes, and in only one or two cases has so high an indigotin content as Mr. Bloxam assumes is normal been recorded. These were in cases of the Java plant (Ind. arrecta, which contains an exceptional amount of indigotin, and was only being cultivated on a small scale during the season from which Mr. Bloxam's conclusions are drawn) under peculiar conditions of manuring. It would be more accurate to place the average indigotin content of the plant used during the season quoted by Mr. Bloxam at 0.3 per cent., so that his estimate of the efficiency of the manufacturing process should be doubled.

As a matter of fact, recent work, carried out with attention to the details I have enumerated, has shown that the process may with care, but with no modification other than is available to every planter, be rendered as efficient as 70 per cent. to 80 per cent., and that as it is carried out by the average planter it seldom falls below 60 per C. BERGTHEIL. The Research Station, Sirsiah, Mozufferpore, India, October 10.

cent.

The Leonid Meteors.

THOUGH the Leonid epoch of 1905 does not seem to have been marked by a great abundance of shooting stars, a magnificent aurora having unexpectedly taken the place on the evening of November 15 of the shower anticipated later on that night, yet it is probable that in the absence of moonlight and cloud the radiant in Leo would have been found to be more active than seemed to be the case. The phase of the moon renders the conditions for good observations more favourable in the present year, and it is probable that if the weather during the critical period turns out fine, Leonids will be observed in considerable numbers. In 1906 these meteors become due on the night of November 15. The anticipated display is connected by the nineteen-year period with the shower of November 14, 1868, and, like the latter, will be visible over both Europe and America. As calculated by the writer, the principal maxima take place on November 15 at 12h. 45m., 14h., 19h., and 21h. 40m., G.M.T. These maxima will therefore occur on the morning of November 16, the first two being visible here, while the remaining two, which repre

sent by far the stronger portion of the shower, will fall to the lot of American observers.

The calculated intensity of the shower is rather inferior to that of its prototype of 1868; besides, the first maxima fall early in the night, and may not, therefore, be seen at their best. Nevertheless, the present epoch is a welldefined one, and should yield satisfactory returns to the vigilance of meteor observers.

Of the minor showers associated with the period, the most interesting occur on November 16 between 13h. and 14h., and on November 17 from 13h. to 18h. Dublin.

The Rusting of Iron.

JOHN R. HENRY.

IN reference to the discussion on the rusting of iron in recent numbers of NATURE, I happen to have a curious specimen illustrating the accumulating of rust which may possibly be of some little scientific value. It is a horseshoe which was dug up some years ago by a child out of the sand on the site of the battle of Prestonpans, near Edinburgh. It was given me by the child's father, who was with him at the time. The shoe is now very irregular and lumpy. The thickness of the naked iron can be made out at one spot, where it is partially denuded. It is just three-eighths of an inch. But with the mass of what I can only describe as rust, and, I presume, sand-some small pebbles are, too, imbedded in it-it is in one spot as thick as 2 inches, and in girth it there measures 6 inches. No part of it is wholly clear of rust; the smallest girth is 4 inches.

The famous battle was fought on September 21, 1745, and the supposition is that the shoe, if not the horse, was lost there. The supposition is probable enough. If correct, the rust would represent the accumulation in a century and a half. I may add that I have some specimens of pig-iron which were turned out at foundries here fifty years ago, and have been in the open air ever since. They have just a brown coat, but the coat is of no perceptible thickness. JOSEPH MEEHAN.

Creevelea, Drumkeeran, October 29.

interesting disquisition on the old belief in spontaneous generation as an explanation of the origin of the organisms of putrefaction, pointing out how this was due in part to the supposed inconstancy of species in Protista, and that this in turn resulted from the want of knowledge of their life-histories; how this knowledge was supplied in the first place by the Rev. W. H. Dallinger and Dr. Charles Drysdale for and Protozoa, and for the Protophyta by F. Cohn later by von Koch, who perfected the methods of culture devised by De Bary for the study of the fungi. In his remarks on reproduction by syngamy, Prof. Hartog distinguishes between exogamy and endogamy, the rhizopod Trichosphærium affording an example of the exogamous conjugation of biflagellate isogametes, while the heliozoan Actinosphærium practises endogamy.

Referring to the pelagic foraminifer Globigerina (p. 61), the author says that after death the tests. sink to the bottom of the sea to form the "Globerina ooze (sic), at depths where the carbonic acid under pressure is not adequate to dissolve the more solid' calcareous matter." On the following page we read:-"Some Foraminifera live on the sea bottom

THE

PROTOZOA AND STATOZOA.1

HE late publication of the first volume of this well-known series has enabled the authors -to incorporate some of the results of the more recent researches upon their several subjects. Taken in conjunction with the earlier published volumes, the work seems to fulfil the purpose of providing an intelligible and adequate survey of the entire animal kingdom without giving undue prominence to particular groups. Prof. Hartog's share in the work makes a welltimed appearance in the year which has witnessed something like a crisis in the history of protozoology. His chapters are full of suggestive comparisons and analogies, and their value is increased by the addition of copious footnotes. Some of the statements are not supported by references, as, for example, where he speaks of the presence of a contractile vacuole in the zoospores of algae and fungi without mentioning any specific instances of this condition (p. 15).

The essential complexity of the simplest manifestations of living matter is made evident, and Prof. Hartog does not harmonise the vitality of protoplasm with the vagaries of a drop of oil or of a bubble. The segmentation of the oosperm of Metazoa and Metaphyta is compared with the sporulation of the Protista, both phenomena being characterised brood-formations (p. 31).

as

In the second chapter the author begins with an 1 "The Cambridge Natural History." Vol. i. Protozoa. by Prof. Marcus Hartog; Porifera (Sponges), by Igerna B. L. Sollas; Colenterata_and Ctenophora, by Prof. S J. Hickson, F.R.S.; Echinodermata, by Pro'. E. W. MacBride, F.R.S. Pp. xvii+671; illustrated. (London: Macmillan and Co., Ltd., 1906.) Price 175. net.

FIG. 1.-Cerianthus membranaceus in its tube. Colour pink, with tentaclesannulated pink and brown. About 35 cm. in length. From "The Cambridge Natural History," vol. i.

even at the greatest depths, and of course their shell' is not composed of calcareous matter. There is. nothing to indicate to the reader why this is more obvious than any of the other plain statements in the book.

The last three chapters of Dr. Hartog's treatise deal with the Sporozoa, the Flagellata, the Ciliata, and the Suctoria. As an illustration of the rapid' strides of recent years, he notes that seven years ago. no single species of Sporozoa was known in its complete life-cycle. It would have been better to have used the general expression body-cavity" instead of cœlom" on p. 105. Colom and hæmocol are both body-cavities, just as clothes props and thoroughbreds are both horses!

The importance of investigations into the life

histories and microchemical properties of the Protozoa, which may be said to have achieved their present culmination in the life and death of Schaudinn, is worthily presented by Dr. Hartog.

Miss Sollas's three chapters commence with a brief historical introduction, followed by a lucid description of two typical British sponges, Halichondria panicea and Ephydatia fluviatilis. The traces of a nervous system referred to on p. 39 of this volume are not to be found here. Chapter viii. concludes with a key to British genera of sponges, comprising seventy-one names, and chapter ix. deals with questions of reproduction, physiology, and the formation

of flints.

Turning now to Prof. Hickson's valuable contribution, we note that he treats the Coelenterata and the Ctenophora as separate phyla instead of regarding the former as divisible into two branches, the Cnidaria, those which are armed with stinging threads, and the Ctenophora, those which are provided with swimming plates. A more serious change which he has introduced is the resolution of the old order Hydrocorallina into two distinct orders, Milleporina and Stylasterina, the former second, the latter

Prof. Hickson's last chapter is concerned with those wonderful creatures of the plankton, the Ctenophora. In describing the planes of symmetry of the body, the author speaks of the tentacular or "transverse plane and of the "sagittal" plane. These animals show no antero-posterior differentiation, and only in one order, the Platyctenea, do they exhibit dorso-ventral differentiation; their symmetry is biradial, and it is undeniably inaccurate to saddle them with transverse and sagittal planes. If a comparison with higher forms must be made, there are strong reasons for the belief that the tentacular plane of the Ctenophora should be likened to the sagittal plane of Bilateralia.

In his account of the siphonophoran body (p. 298), Prof. Hickson evinces a general willingness to steer clear of wearisome polemical discussions; in this case the difficulty might have been surmounted by calling the various parts of the colony neither organs nor zooids, but organozooids.

The volume concludes with six chapters on the Echinoderms from the pen of Prof. MacBride. In the classification of the Ophiuroidea the author has followed Prof. Jeffrey Bell's system, which seems to

sixth, in the list of orders, separated in the text by the Gymnoblastea, the Calyptoblastea, and even the Graptolitoidea.

With regard to the relations between the hydroid stock or hydrosome and the medusoid gonophore or medusome of the Hydrozoa, Prof. Hickson gives expression to the perennial vexed question as to whether the hydrosome preceded the medusome or vice versâ; he does not assist the reader by adducing analogous instances. The stock and sexual stolon of some annelid worms would seem to offer an almost exact analogy to the hydroid and medusoid phases of a hydrozoan; the medusome might even be regarded as an epitokous sexual phase, the stock being the parent form, indifferently whether it is fixed or free; the liberation of the medusæ (where this occurs) would correspond broadly with the swarming of the epitokes.

The general treatment of the three classes, Hydrozoa, Scyphozoa, and Anthozoa, leaves little to be desired within the limits prescribed by the nature of the work, and prominence is given to bionomical questions.

have achieved the distinction of permanency. The tabulation of the families of Asteroidea is based upon Prof. Perrier's system, and gives a very different sequence from that based upon Mr. Sladen's orders, also in vogue at the present time. In the chapter on the Echinoidea (sea-urchins) there are interesting passages on the physiology of the pedicellariæ; the chapter on the Holothuroidea (sea-cucumbers) contains a humorous though instructive comparison between the organisation of a Synaptid and that of a Sipunculid.

The final chapter is devoted to questions of development and phylogeny. It seems probable to Prof. MacBride, and will doubtless appear so to his readers, "that Vertebrata and Echinodermata both arose from Protocœlomata." It remains to be added that the illustrations are excellent, and many of them original. The term "Statozoa," originally applied to certain Echinodermata, but not generally adopted in that connection, may be conveniently extended so as to include such animals as sponges, cœlenterates, and echinoderms, in which a fixed condition is either actually or phyletically predominant.

THE

THE INTERNATIONAL GEODETIC CONFERENCE AT BUDA PEST.

HE International Geodetic Association held its triennial conference at Buda Pest from September 20 to 28, and I had the honour of serving as the delegate of our Government. By the kindness of the Hungarian Academy the meetings were held in their handsome building, and the arrangements for our reception, which had been made by M. Louis de Bodola, were in every way admirable. Before considering the scientific work of the conference I may mention that the Prime Minister, Dr.

Wekerle, invited the members of the "Permanent Commission " to dinner, and that the Archduke Joseph afterwards received all the delegates at the palace. On subsequent days the Burgomeister of Buda Pest gave a dinner in our honour, as also did Count Albert Apponyi, Minister of Public Instruction. The work of the conference was more interesting than that of any other at which I have been present, and the time was barely sufficient for the adequate discussion of many subjects of importance. In an article of this character it will clearly be impossible to do more than indicate in general terms the subjects which were considered.

The systematic observation of the variation of latitude, which is the special province of Dr. Albrecht, was naturally the subject of much discussion. The existence of a mysterious term in the expression for the position of the pole was discovered some years ago by Prof. Kimura. If this term, which is denoted by the letter z, has a real physical existence, it would indicate that the equator oscillates backwards and forwards, moving parallel to itself. It appeared that observations conducted in the southern hemisphere would quickly determine the reality of the supposed motion. Accordingly, at the conference of Copenhagen in 1903 it was resolved that observations in the southern hemisphere should be instituted, and should be carried out for a period of at least two years. The southern observations of latitude are to be made at

Bayswater, West Australia, where Dr. Hessen began his observations on June 6, 1906, and at Oncativo, in the Argentine Republic, where Prof. Carnera began work on May 5. These two stations are in S. latitude 31° 55'. We also heard from Mr. Innes that latitude observations will probably be commenced at Johannesburg (S. latitude 26° 12′) by the end of the present year. With regard to the observations in the northern hemisphere, it was resolved that they should be continued, at least until the year 1909, when the next conference will meet. The northern stations are Pulkova and Leyden, and in N. latitude 39° 8' Mizusawa, Charjui, Carloforte, Gaithersburg, Cincinnati, and Ukiah, together with Tokyo in latitude 35° 39'. Prof. Helmert gave an interesting account of the present condition of the whole investigation, and he directed attention to certain oscillations or systematic errors of which the physical meaning is as yet altogether obscure. Whatever their meaning may be, their magnitudes are excessively minute.

Another report of importance was one by Dr. Albrecht on the use of wireless telegraphy for the determination of differences of longitude. He concludes that this method may be relied upon to give as good results as those derived from telegraphy through wires.

Dr. Hecker had undertaken, at the expense of the association, a second long sea voyage for the purpose of determining the value of gravity at sea. His first Voyage was from Portugal to Brazil, and the

1 The observations at Cincinnati will, as I understand, be discontinued shortly.

second was in the Indian Ocean and across the Pacific. He presented a short preliminary report, in which he stated that the intensity of gravity for the deeper part of the Pacific Ocean is approximately normal, and agrees closely with Helmert's formula of the year 1901. His experience in the first voyage had enabled him to effect considerable improvements in the procedure. The method depends upon the determination of the temperature of boiling water and the simultaneous observation of the height of the barometer. The difficulties in attaining at sea to the requisite degree of accuracy are so numerous that it is matter of surprise that trustworthy results can be obtained. There seems, however, to be now no doubt that we may trust his conclusions. Dr. Hecker exhibited his apparatus with five barometers furnished with the means for obtaining continuous photographic records of the height. One of the greatest difficulties to be contended with is the motion of the ship, for the pitching and rolling make the mercury in the barometer " pump,' " and the photographic trace of the barometer height is marked with regular notches. Dr. Hecker is to be congratulated on the skill with which he has overcome this and many other difficulties. His conclusions form one of the most noteworthy acquisitions to geodetic knowledge of the last twenty years.

MM. Claude and Driencourt gave an account of the use of their prismatic astrolabe. It gave me the impression that it might be an instrument of much use to geodesists.

The measurement of base lines naturally afforded an important subject of discussion, and M. Guillaume, assistant director of the International Bureau of Weights and Measures at Bréteuil, gave an admirable account of the recent improvements which have been effected in the use of the Jäderin wires. It would appear that the measurement of base lines has now reached such perfection that we cannot look for any great advance in geodetic accuracy in this direction. Errors due to triangulation accumulate rapidly, and the modern practice is to measure short bases about every 200 miles. The Simplon Tunnel has been used by the Swiss geodesists as a base line, and was measured by the Jäderin apparatus. The railway company was good enough to surrender the tunnel to the geodesists for five clear days, and by means of continuous work day and night they were able to complete their task. A special form of tripod for supporting the wires was devised; it rolled along the railway lines, and in this way the labour of transporting the tripods was considerably diminished.

The national reports furnished by the several delegates were in many cases of great interest, but I can only refer to a few of them.

The work of the Swiss in the measurement of a base along the Simplon Tunnel has already been mentioned.

A proposal has been made for the collaboration of the French and Italians whereby the island of Sardinia may be linked to Corsica and to the Italian mainland.

The French delegates gave a final account of the This work measurement of the great arc of Peru. took five years, and eleven officers of the Service Géographique de l'Armée and twenty-eight underofficers and soldiers took part in it. Several of the staff died of exposure and hard work in the Cordillera, and the conference received this intimation standing, in token of respect to their French comrades who lost their lives in the cause of science.

I myself presented reports from Colonel Burrard, R.E., on the work in India, and from Sir David Gill, Colonel Morris, and Mr. Simms, on the geo