matters they would assuredly derive greater pleasure and profit from their pursuit, and do much more towards the progress of science. Mr. Young himself, however, notwithstanding the good advice he gives, is not always careful in drawing conclusions, geological evidence being sometimes quite overlooked. Thus, we find him stating that the coal-measures (meaning, of course, the whole series of strata above the Millstone Grit) are "evidently of land and fresh-water origin," because they have yielded no marine organisms, save in one thin local bed near the top of the series. The occurrence of this stratum with its marine remains, indicates, as he believes, the return for a short time of the sea, which had for a very long period "been completely shut out by barriers." Mr. Young is welcome to his belief. If every bed or series of beds in which no marine organisms occur must necessarily be of fresh-water origin, the lakes of old must have been something worth seeing. There are several points suggested by the catalogue that we should like to have taken up, but our space is exhausted, and we can only conclude by strongly recommending Mr. Armstrong's work to the notice of our geological readers. J. G.

LETTERS TO THE EDITOR

The Editor does not hold himself responsible for opinions expressed by his Correspondents. No notice is taken of anonymous communications.]

On the Solution of a Certain Geometrical Problem A WRITER in the number of NATURE for September 21, Mr. R. A. Proctor, in the course of a letter on the state of geometrical knowledge in the university, alludes manifestly to the solution of a problem which I have adopted in my edition of Euclid. The matter is of small importance in itself, but nevertheless as some points of interest are incidentally involved, I request you to allow me the opportunity of offering a few remarks.

The problem is this: to describe a circle which shall pass through a given point and touch two given straight lines. Your correspondent considers that in giving a solution which depends on the sixth book of Euclid, instead of one which depends only on the third book, I exhibit signal geometrical weakness.

The problem, I need scarcely say, is very old; indeed, so old that a writer who had been long engaged in teaching could not pretend to solve it afresh, for he would certainly have in his memory one or more solutions which had become quite familiar to him. The solution by the aid of the third book is well known, for it occurs in several of the collections of geometrical exercises. The solution which I have adopted is also old, but seems not so well known. It is, I think, conspicuous for simplicity, elegance, and completeness. The demonstration is of the best and most impressive kind, requiring no laborious effort to understand and retain it, but being almost self-evident from the diagram. Even if the problem be treated as an isolated exercise, the solution which I have preferred will sustain a favourable comparison with that which more commonly occurs.

But the determining cause of my choice was the position which the solution occupies as one of a connected series. I have just before treated a similar problem by the third-book method, so that if the same method had been used for the present problem, there would have been only repetition without any substantial increase of knowledge; whereas by the course adopted the student is introduced to fresh and valuable matter. The principle of similarity and the notion of a centre of similitude are most instructively involved, and the student is prepared for a subsequent investigation, which is similar but more complex. To sum up, the third-book method would have constituted no advance in the subject, where the sixth-book method takes a step important in itself and in its consequences; and therefore, following the example of an eminent geometer, I adopted the latter method. I may perhaps venture on the strength of my own experience as to the utility of the solution, to recommend it to the attention of other teachers.

It is very important to bear in mind the distinction between what I may call absolute and relative merit which I have just exemplified. The solution of a single problem furnished by a candidate under examination, or by a contributor to a mathema

tical periodical, is very different from the investigation of one on of a chain of propositions in a mathematical treatise. In the former case there are no antecedent or subsequent conditions to regard; in the latter case we have to consider what agrees best with the whole scope of the work, with what is to follow as well as with what has gone before. A writer, after arranging a paragraph or a chapter in what seems the best manner, may find himself constrained at a subsequent stage to make changes which would have been unnecessary, perhaps even undesirable, if the earlier portion had stood alone. Then, if a reader opens the book at random and criticises a passage without any regard to the author's sense, the criticism may very naturally be quite inap. propriate.

There is, however, a very important consideration of another kind which has been frequently disregarded, but which is pressed upon our notice by the interest at present felt in geometrical studies. Let us determine the reason which leads us in some, or in many, cases, to prefer a solution which involves only the third this, I apprehend, is merely a persuasion that Euclid's order is a book of Euclid to a solution which depends on the sixth book; natural order, so that in a well-arranged system the propositions of the third book ought to precede those of the sixth book. I am of this persuasion myself; I think that no scheme can be perfect, and, on the whole, I am well satisfied with Euclid's But there are places where Euclid is strong, and there are places where Euclid is weak; and the position which he has assigned to the last three propositions of his third book, must rather be classed with the latter than with the former. His object, of pentagon, and we cannot be surprised at the introduction of that course, must have been to lead up to his construction of a regular remarkable process. But I have always envied the advantage in this respect to be claimed for the non-Euclidean systems, which transfer these propositions and place them after the doctrine of similar triangles; thus the long and rather artificial treatment which they receive from Euclid is superseded, and the proposttions become almost intuitive. Hence, in fact, if we have recourse to the sixth book of Euclid when we might have accom plished our end by the aid of the first thirty-four propositions of the third book, we may be fairly liable to the charge that we have not adopted the simplest and most natural method; but the last three propositions of the third book are quite different in kind from the others, and instead of using them, it may be really as simple and as natural in many cases to use the principle of similar triangles.

I shall be obliged to any person who may be skilled in practical geometry if he will state what he considers the best method of actually solving the problem, supposing that both circles are to be determined which satisfy the conditions. I assume that we have the aid of compasses and also of one of the ordinary contrivances for drawing parallel lines. This is a matter of some interest, though of course unconnected with the theoretical solution of the problem.

I should be glad to make some remarks on the general subject which led to the notice of the particular problem I have discussed, but at present I have not sufficient leisure. I must content my self with having shown that the course into which I am supposed to have drifted by geometrical incapacity, was adopted deliberately under the guidance of reasonable geometrical knowledge. 1. TODHUNTER

St. John's College, Cambridge, Oct. 21

Structure of Fossil Cryptogams

It was unfortunate that at the recent meeting of the British Association, Prof. Williamson's paper had to be discussed in 1 very hurried manner, and he is, no doubt, justified in taking care that there shall be no misunderstanding as to the real point at issue." I do not think that he has brought it out very plainly in his paper in NATURE, and perhaps, as he mentions me as an opponent of his views, I may be allowed to state precisely in what respects I differ from him.

First, as to matters of fact. Prof. Williamson speaks of the central structure of the stems of the extinct Lycopodiacer as a "vascular medulla," by which he explains that he means a "structure containing vessels," and that there shall be no mis apprehension he adduces Nepenthes as possessing it; the instance is a well-known one, and leaves no room for doubt as to Pro Williamson's meaning. Now from the examination of specimera, and of the drawings of them published by Mr. Carruthers (the accuracy of which I believe Prof. Williamson does not dispute) I am quite satisfied that the central structure consists wholly cế

scalariform vessels, and that there is in fact nothing medullary or medulla-like about it.

Outside this central structure is what Mr. Carruthers terms the investing, and Prof. Williamson the vascular woody cylinder. I believe that Mr. Carruthers is right in looking upon this as belonging to the central axis, which is therefore composed of two parts. I find, which I did not sufficiently appreciate at the time, that Prof. McNab regards this investing cylinder as homologous with the cylinder of wood cells surrounding the central axis of fibro-vascular bundles which is met with in many recent Lycopodiaceae. From this I certainly dissent for two reasons; (1) because I think its equivalent is to be found in the central axis itself, and not outside it; (2) because it is not composed of wood cells but of scalariform vessels.

Secondly, as to opinions. The terms Exogen and Endogen, as is pretty well known, were founded upon a mistake. A great deal too much has been made of the difference implied by them; in fact, if we compare a one-year-old dicotyledonous shoot with a monocotyledonous stem, we find that it does not exist. Prof. Williamson will look at the stem of the common artichoke, he will find it difficult to convince himself that he is examining exogenous" plant at all.

an

If

The imagined characters which were implied by these terms are, nevertheless, as everyone knows, correlated with others, which in the aggregate enable phanerogamic plants to be divided into two satisfactory groups; but this is certainly not equally the case with the groups into which Prof. Williamson would divide the vascular cryptogams. These groups, I think, most botanists will agree in considering in the highest degree unnatural, inasmuch as, assuming the vegetative distinction upon which they are founded to exist, it is a wholly artificial ground for classificatory purposes. Nor is it any argument that one vegetative character must be good because others are in use, since the simple answer is that these coincide with natural divisions, while Prof. William

son's does not.

I shall not dispute Prof. Williamson's position that our living Lycopodiace should be interpreted by the more complete extinct types. To do this, however, the extinct types must be thoroughly understood; when we are dealing with imperfect material, comparison with the more perfect but less highly developed existing plants is not only justifiable but necessary.

It is obvious that the great development of the stem in the Lycopodice of the Coal Measures was correlated with their arborescent habit. I am inclined to think with Prof. William. son that the stem increased in thickness; it is certain that Lepi dodendron was branched, and not improbably also Sigillaria. The branches as they were gradually developed must have been the cause of an increasing strain upon the stem; it seems to me more congruous with known laws of the response of structure to circumstances, to conclude that the stem was proportionately developed as the strain increased, than that the stem should have been produced once for all of its maximum thickness without reference to the crown of branches that was finally to surmount it. I am quite prepared therefore to admit that the inves' ing cylinder may have increased by external additions, and probably did do so; this would of course imply the existence of a cambium layer outside it. There is some analogy for this in the recent Isocles, where we have a "slight woody mass which occupies the longitudinal axis of the stem, but encloses no pith."+ Outside this we have a "bark-forming" cambium (which also adds, but more sparingly, to the wood mass); in Sigillaria and Lepidodendron we might have had a cambium not merely renewing the bark but adding to the central axis.

In whatever way the increase took place, it was, as I think, nothing more than an incident in the life history of a particular race of plants, nothing more than an adjustment to an arborescent habit dropped when the arborescent habit was lost, but showing a lingering ancestral tendency in Isoetes. Comparing a simple stemmed palm with Dracena, we have a parallel instance of the strengthening of the stem pari passu with the continued development of a system of branches; only in Dracaena it is the circumferential part of the stem alone which developes.

If I am right in regarding a stem gradually developing in size as the necessary correlate of a large system of branches, Prof. Williamson's view practically amounts to the old division of plants into trees and herbs. I cannot see how it can afford any safe ground for a re-arrangement of the vascular cryptogams. W. T. THISELTON DYER

London, Sept. 26

Monthly Micro. Journ., 1869, p. 169. Hofmeister, Higher Cryptogamia, pp. 356, 361

The Solar Spectrum

MAY I venture to suggest that quite possibly something of value might be obtained by observing the sun during totality with a spectroscope of reasonable dispersive power (say four or five prisms) without a collimator, or even simply with one of the socalled meteor spectroscopes.

If the bright rays and rifts are really and simply (or even mainly) composed of the green-line-giving substance, they will give a well-defined green image; if they are formed by reflection (either at the sun or in our atmosphere) of ordinary sunlight, they would be so dispersed as to be invisible or nearly so, and if formed by the reflection of chromosphere light they would give several images, the red (C) and blue-green (F) being most conspicuous. C. A. YOUNG

Hanover, N.H., U.S., Sept. 13

** Arrangements have already been made for carrying out a similar suggestion to this by the Eclipse Committee; and the corona will also be observed with an open slit.-ED. N.

Eclipse Photography and the Spectroscope

I

THE endeavour of the Eclipse Committee to secure some uniformity in the photographs from different stations next December does not appear to be duly appreciated, it being contended that immense "personality" shown in various photographers' manipulation must frustrate the good intention. submit that in this case the personality is greatly over-estimated; that a number of competent photographers taking the same subject would probably produce, under any ordinary circumstances, pictures bearing considerable resemblance; while by using like apparatus and giving exposure of the same duration, we might safely predict a similarity of result amply sufficient for comparative purposes, and for the identification of structural peculiarity should it exist.

Among others there is a possible advantage to accrue from uniform work by the philosophers which I have not seen or heard noticed. Supposing the outer corona, rays, streamers, or any portion of the apparently luminous matter be terrestrial, is it unreasonable to expect that photographs, taken at stations more or less widely separated, will, when properly combined in the stereoscope, give clear ocular proof of the sublunary situation of

such luminous matter?

Phenomena of Contact

HENRY DAVIS

MR. STONE can safely be left to meet the arguments specially addressed to him in Prof. Newcomb's letter; but as the subject relates to the only point of importance touched on in Prof. Newcomb's criticism of my chapter on the sun's distance, I crave permission to meet his general argument.

I submit that he tries to prove too much.

He admits that the phenomenon of irradiation exists in the case of a disc. The sun's disc, then, must be to some extent enlarged, and the dark disc of Venus must be to some extent reduced by the effects of irradiation. Now this being so, what becomes of the cusps, when Venus is all but wholly on the sun's disc? Either the irradiation is diminished near the cusps or it is not. If it is diminished there must be distortion, because the disc of Venus is then not uniformly reduced: if the irradiation is not diminished a ligament must appear.

Let any one draw a large circle (say a foot in diameter) on paper, and a small one (say an inch in diameter) extending very slightly (say by the twentieth of an inch) beyond the boundary of the first; and let him blacken the smaller circle as well as all the space outside the larger one. He has then a space representing the disc of the sun with a very large Venus upon it near the time of internal contact. Now let him conceive the whole of this space (a sort of exaggerated crescent) slightly enlarged as by irradiation, the enlargement-fringe extending outside the boundary of the large disc and inside the boundary of the small black (incomplete) disc. He will find the conception of this enlargement exceedingly easy everywhere save near the cusps; but here there is a difficulty in determining how the fringe outside the larger disc is to be joined on to the fringe inside the smaller disc. If he can conceive these two fringes meeting in such sort as to leave the reduced outline of the small disc completely circular up to the very points in which it meets the enlarged outline of the large disc, he will have done what Prof. Newcomb's theory requires. But note, this must be done for the case when the fringe of enlargement is wider than the twentieth of an inch, by which the small disc overlaps the large one. When this is the

case, the task will be found to be impracticable; but even when the overlap of the small disc is greater, the task can only be achieved by actually making new cusps out of the irradiation fringes. (A figure would make this explanation much simpler.)

Prof. Newcomb says that he is decidedly of opinion that the irradiation of an extremely minute thread of light is not the same with that of a large disc. He does not seem to notice that if this is so, Venus just before, at, and just after internal contact, must be distorted. This even if-admitting the enlargement of the sun's disc-he denies that the disc of Venus is reduced by

irradiation.

He fails also to observe that a peculiarity such as distortion, or the formation of a ligament, may escape the notice of inferior or not very attentive observers, and so all his negative observations be explained. It is no proof of superior skill in observation to see no signs of an illusory effect. Until we have observers who recognise no traces of irradiation when looking at the solar disc, we must believe that (as Mr. Stone has, I think, already asserted) the non-recognition of distortion or ligament formation is due to inattention, or want of observing skill. That this should be more common than close and careful scrutiny is not a very surprising circumstance, and proves nothing. RICHARD A. PROCTOR

Oceanic Circulation

IN NATURE of August 17, I have just seen the report of the discussion on Dr. Carpenter's paper on the above subject read at the late meeting of the British Association.

Dr. Carpenter, explaining the movements on thermodynamic principles, states that he has "found the primum mobile of this circulation was not in equatorial heat but polar cold," and explains that " (1) As each surface-film cools and sinks, its place will be supplied, not from below, but by a surface influx of the water around; and (2) the bottom stratum will flow away over the deepest parts of the basin, while, since the total heat of the liquid is kept up, there will be an upper stratum which will be drawn towards the cold area, to be precipitated to the bottom and repeat the action. Apply this principle to the great oceanic area that stretches between the equator and the poles, we should expect to find the upper stratum moving from the equator towards the poles, and its lower stratum from the poles towards the Equator. That such a movement really takes place is indicated, as it seems to me, by various facts."

It does not appear, however, that Dr. Carpenter has well established his claim to the theories in question, while, in a pamphlet on the same subject, published in 1869 by Dr. Adolph Mühry of Göttingen, we find such passages as the following:-" As the cause of the latitudinal circulation we have assumed the difference of temperature in the water between the equator and the pole." He honestly gives Arago the credit of being, perhaps, the first to put forward this view in 1836; and after remarking (p. 11) that it might be considered doubtful whether it is the upper warm current from the equator or the under cold one from the pole that ought to be considered the primary, he says (p. 12) "For us the primary arm' is the heavier, i.e., the colder polar stream, which, in obedience to gravitation, falls in a horizontal direction toward the lighter water of the hot zone; and the secondary 'arm' is the returning antipolar. It moves to replace what flows away, and is, therefore, the compensation-arm.'

Here, without following Dr. Mühry any further, we find the thermodynamic theory advanced by Dr. Carpenter, and his primum mobile as well; but by giving him credit for ignorance of Dr. Mühry's work, we may excuse him for laying claim to what is there put forward, and accepting therefore the commendation of others as unknowing as himself. J. B.

Ice Fleas

DURING a recent ramble upon the Morteratsch Glacier, I also observed a large number of the minute black creatures described by Prof. Frankland in NATURE, No. 100. My attention had been directed to them ten years ago by Lord Anson on the "snow-bones," near the summit of the Egischorn. They are only nominal "cousins" of the flea (Pulex) of civilised life, and are not at all related to Dapnia, the "water flea," but are closely allied to the minute insects which are often seen on the surface of stagnant water, resembling grains of gunpowder, and skipping partly by help of their forked tail, folded under them so as to serve as a foot, hence their name Podura, or "skip-tail." They have been named by Agassiz Desoria saltans. Their food, I conjectured with Prof. Frankland, consists of "red snow" and

other microscopic algae. Not being myself within reach of s good library, I can only furnish your readers with a key to furt information. С. А. Јонла

IN NATURE of 28th September, Prof. Frankland, in intrs ducing the ice flea to the readers of NATURE, uses the expresse "if known at all," and concludes by asking information ains it. The glacier flea, Desoria glacialis, was noticed and described by Prof. Agassiz as far back as 1845, in his Ascent of the Wetter horn on the 29th of July of that year. Not having Agae, work at present beside me, I cannot refer to it, but these Beas are noticed in an extract translated from an account of the ascert and published in Hogg's Weekly Instructor for Dec. 1845, vol p. 221, On the Aar Glacier they are described as being scattered over the "surface of the snow in millions," elsewhere, being collected in masses under the stones on the ice."

The New Dynameter

R. C.

THE letter from the Rev. T. W. Webb in your last number is a very tantalising letter. He tells us, and we could not wash to have a better authority, that a new dynameter has been is vented by the Rev. E. Berthon, but he does not tell us how it is constructed or where it can be obtained.

I may take this opportunity of mentioning a makeshift dyn meter which I have found to answer very well when extreme accuracy is not required.

I have a pocket telescope fitted with a Cavallo micrometer, i.e., a slip of finely divided mother-of-pearl screwed to the dia phragm next the eye-glass. Unscrewing the two last draws of this telescope the end of the second is applied to the eye-piece of the telescope of which the power is to be measured, and the first draw pushed in till the image of the object glass comes shp upon the mother-of-pearl. The diameter of the image is s given in divisions on the mother-of-pearl, the value of which, a hundredths of an inch, has been previously ascertained.

Notaris on Mosses

W. R.

WITH reference to the notice of De Notaris' book on Musse, I am informed by Dr. Dickie that the genus Habrodon was discovered in Great Britain several years ago by the late Mr. McKinlay, of Glasgow, and that he had received from Mr. Wilson about two years ago from his district Conomitrium juliaria. Dr. Dickie sends specimens of Hobrodon Notarisii gathered at M. J. BERKELEY Killin by Dr. Stirton.

In the review referred to, Prof. De Notaris was erroneously described as of Geneva, instead of Genoa-En, N.

"Newspaper Science "

My attention has just been called to a letter from Mr. Davil Forbes which appears in NATURE, Sept. 21, under the beat "Newspaper Science," and in which that gentleman, writing from Boulogne, pathetically describes the emotions with which he rea a recent "article" in the Globe on 66 Krupp's" Gun-manufactory at Essen. I need hardly say how deeply I deplore the shock which I have unwittingly been the agent of inflicting on your||| distinguished correspondent. It will be some small satisfaction if you will allow me to express the hope that the "desired result" of Mr. Forbes's "reluctant" compliance with the advice of his "medical man," and most wise resolve "to eschew every thing scientific for the next few weeks at least, in order to recruit before the winter labours commenced," may not be utterly defeated by the perusal of "a specimen of English scientie opinion," of which I am unhappily the author. It would be a terrible reflection indeed, that a stupid error on my part had. perhaps, imperilled the accuracy and success of Mr. Forbes': "winter labours." The blunder (or rather blunders) occurred as follows:-I, too, was knocked up with work," but being myself a "medical man naturally only in part carried out my own prescription. I would, for the sake of Mr. Forbes, and the credit of "English scientific opinion" in the estimation his "French acquaintance," I had exercised a little more discretion. However, unfortunately, I stumbled on the Krupp factory, and all forgetful of my dilapidated mental condition wrote a note-paragraph (I never write "articles"), which I vainly imagined might have been innocent and interesting. It is not always possible to compress even the manuscript necessary for a paragraph on to a single sheet of paper, and I grieve to say that after my paper had passed the editorial eye three words

forming the connecting link of a sentence must have been dropped. What I intended to say, without the slightest notion of giving a "technical or scientific" opinion, was, "The iron is alloyed in crucibles, formed with certain clays and a preparation of plumbago." The words italicised disappeared in some mysterious way. The next of my idiotic sentences goes on to talk about the crucibles, or "creusets," as, to the great scandal of Mr. Forbes, I ventured to call them. If I could stop here, an humble apology for my fault might, perhaps, serve my purpose, but, alas! I have more to answer for. Vaguely dreaming of the foot-pound, I actually wrote kilometre for kilogrammetre, when speaking of the power of the new steam hammer; and, worst of all, I also WROTE "Sheffield Gun Metal."

Can I ever hope to be forgiven when thus I write myself

down an ass?

MEDICUS

was found frozen to the under one. They were then separated, and one of them was allowed to remain supported at the ends and weighted by ice at the middle. În a few hours it had bent into a curve, the versed sine of which from a chord uniting the two ends was, at least, two inches. In fact, when the rectangles are thin, and the weight carefully laid on, flexure commences very soon, and may by cautious manipulation be rendered very considerable. I think Mr. Froude told me that in his experiment the molecules were "in torture," and that they in great part recovered their positions when the weight was removed. In the foregoing experiments the flexure was permanent.

I tried to bend the rectangle just referred to back again by reversing its position and weighting it with the same block of ice. But whether owing to my want of delicacy in putting on the weight, or through the intrinsic brittleness of the substance itself, it snapped sharply asunder.

I left in your hands when quitting London an exceedingly interesting paper by Prof. Bianconi, in which are figured the results of various experiments on the bending glacier ice confirm his results. August 4

Nos. 99 and 100), was written I have examined a mature female, transmitted, with other examples, by the Trustees of the Sydney Museum to the National Collection, and am enabled to make the following additions :

1. The oviduct in its developed conditions is, with regard to its internal structure, surprisingly similar to that of Menopoma.

2. The ova are expelled through the oviduct, and not through the peritoneal slits; they receive in the oviduct a coating of an albuminous substance as in Batrachians.

3. The caudal termination of the vertebral column is subject to individual variation. In one example the neural and hæmal elements are continued far beyond the notochord, and are confluent into a tapering band, which is segmented, as is the case in some specimens of Dipterus

or Ctenodus.

ALBERT GÜNTHER

ON THE BENDING OF GLACIER ICE*

M R. MATTHEWS and Mr. Froude had supported long rectangles of ordinary ice at the two ends, weighted them in the centre, and thus caused them to bend. The ice employed, if I recollect right, was of a temperature some degrees below the freezing point, and in my little Alpine book recently published I expressed a hope that similar experiments might be made with glacier ice. I have been trying my hand at such experiments. The ice first employed was from the end of the Morteratsch Glacier, and when cut appeared clear and continuous. A little exposure, however, showed it to be disintegrated, being composed of those curious jointed polyhedra into which glacier ice generally resolves itself when yielding to warmth. Still, when properly supported and weighted, a long stout rectangle of such ice showed, after twelve hours, signs of bending.

I afterwards resorted to the ice of the sand cones, which, as you know, is unusually firm. From it rectangles were taken from three to four feet long, about six inches wide, and four inches deep. Supported and weighted for a considerable time, no satisfactory evidence of bending appeared; the bars broke before any decided bending took place. Smaller bars were then employed. Two of these were placed across the mouth of an open square box, their ends being supported by the sides of the box. They formed a cross, and a clear interval of at least an eighth of an inch existed between them where they crossed. The upper one was carefully weighted with a block of ice; after two hours it had sunk down, and

The following is an extract from a note addressed to Prof. Hirst, and sent from Pontresina in the hope that it would reach Edinburgh in sufficient time to be communicated to Section A of the British Association. It was a few hours too late.-J. T.

JOHN TYNDALL I may add that various experiments were subsequently made, and a means discovered of rendering the bending very speedily visible. I hope before long to return to the subject.-J. T., September 28

THE MIGRATION OF QUAIL

THE fact of this little bird having visited England the attention of naturalists as well as sportsmen. this year in such numbers appears to have attracted In the columns of the Field may be found a census giving particoincidence when I mention that there has been here a culars of this migration. And it will appear a curious greater migration of quail this year than ever remembered before. Where they come from is somewhat mysterious. They have been shot in hundreds in some paddocks, and found as numerous as ever in ten days. I can only account for it by stating that it has been a most remarkable year for grass, and consequently cover was good; and this does not appear conclusive, for the grass has been good all over the country for hundreds of miles towards the north, from which direction some appear to think they come. They are found generally in paddocks, where thistles grow. Can there be any common cause affecting these facts? Melbourne, August 10 AUSTRAL-ALPINE

JARDIN D'ESSAI, ALGER IN, 1832 the then French Government conceived the

idea of forming near the town of Algiers a botanical garden, in which all plants likely to be easily grown in Algeria, and which might be useful either for their ornamentation, or from their economic value, should be kept for distribution or for sale. A portion of ground situated between the sea and the public road, and occupying the place of an old hamma or marsh, was selected for this purpose, which is about two miles from the town. In 1867 the Emperor of the French conceded this establishment to the "Société Générale Algérienne," under whose auspices, but under the direct superintendence of M. Auguste Rivière, the gardens at present are.

In addition to the level swamp, the gardens now also occupy the slope of a low hill on the opposite side of the road. The level ground is laid out in alleys which open out into a circular boulevard which surrounds the whole garden. Carriages are admitted to the circular drive only, foot passengers to the cross walks. A stream of fresh water runs through the grounds, forming in one place a small lake.

One fresh from the Botanical Gardens of Europe is astonished at every step taken in the Gardens by the wondrous vegetation which is shown by all the semitropical plants. Descending a few steps from the circular drive, a great palm avenue is entered. This avenue was planted in 1847, and is formed of about eighty trees of the date palm, nearly as many of the Latania Borbonica, and about 150 of the dragon's blood tree (Dracœna draco). The avenue is about ten yards wide, and between every two of the date palms there are two of the dragon's blood tree and one Latania. It terminates in a clump of palm trees which are planted almost to the border of the sea. When it is borne in mind that the date palms are from twenty to fifty feet high, the Latanias averaging about twelve, and the Dracenas about eight feet in height, the general effect of this splendid avenue may be imagined. All the trees were in December last in full flower or fruit, the golden trusses of the date palm contrasting well with the more brightly-coloured clusters of Latania berries. It would require more space than is at our disposal to describe the contents of all the various small avenues that branch off from the main one. The most remarkable smaller avenues are, perhaps, the one formed of bamboo (Bambusa arundinacea), planted in 1863, and forming an immense mass of foliage, the stems supporting which are from forty to fifty feet high, and that formed of about 100 plants of Chamarops excelsa, each about ten feet in height. But remarkable as are these charming subtropical alleys, the visitor is more than surprised when on going towards the portion of the garden where the plants are grouped somewhat according to their natural orders, he finds specimens fifteen feet high of Caryota urens and C. Cumingii, growing with vigour and covered with fruit; of Oreodoxa regia, from Cuba; several plants upwards of twenty-five feet in height; and a plant of Fubaa spectabilis, which is twelve feet high; and then just a few steps more and a parterre alloted to the natural family of the Musaceæ comes to view. As both the plantain and banana are grown in large quantities for their fruit in another portion of the grounds, the family is here chiefly represented by such genera as Strelitzia and Ravenalia. Magnificent specimens of the latter genus, with stems nine to ten feet high, exhibited great combs of flowers. We are not aware if the Traveller's tree has flowered in Europe, and we were not prepared to find it in full flower in Algiers. It has not, however, matured its fruit in this garden. Near this grand parterre stood another with many fine specimens of Yucca, also a magnificent plot of Aralias, A. papyrifera, in full fruit and very handsome; the fine A. leptophylla and A. præmorsa, thickly covered with spines, and the very ornamental A. farinifera; and then one's attention is caught by a large tree (Carolinea macrocarpa) from Brazil, with a couple of dozen of its fruit, each as big as a cocoa nut; by a small forest of Anona cherimolia in full fruit, which is nearly as good as that of the closely related species which yields the custard apple. Near these is an immense tree some thirty feet in height, covered with fruit of the Avocado pear (Persea gratissima); and at its feet is a quantity of guava trees (Pisidium Cattleyanum) crowded with its perfectly ripe, large, pear-shaped, golden fruit. Growing up into the trees, and forming numerous and never-ending festoons, were some specimens of Cacti, chiefly species of Cereus. Some of these were of great size, and one specimen, which had completely strangled a plantain tree some twenty-five feet, was said to have been covered in the autumn with 600 to 700 flowers. It must have been a sight worth a long pilgrimage to see.

Enough has been said to show what a surprising number of semi-tropical fruits luxuriate in the beds of this well-watered garden, and we might add many well-known vegetables to the list, as sweet batat, yam, papaw; but all this while we have been writing of

the great level portion of the garden. Outside of this, and on the other side of the roadway, there is a small hill, two or three hundred feet in height, which slopes towards the garden and the sea, and is traversed by several ascending walks. This is the New Holland district of the garden, and certainly not the least interesting portion of it. In one section of it are different species of Acacia, many of them large trees, twenty to twenty-five feet in height. Of the Proteaceae there were magnificent trees; of the genera Banksia, Hakea, and Grevillea, the collection of species was very large, all of them just bursting into masses of bloom The most important of the trees growing in this corner of the hill was probably Eucalyptus globulus, of which some trees, now about forty feet in height and over four feet and a half in circumference, were planted in 1862, and were then only a few inches high. Young well-established seedlings, of about ten inches in height, are sold for zar a hundred, and large numbers of them have been planted from time to time throughout Algeria by the French Government. This species grows in Algeria with most surprising rapidity, under very favourable circumstances growing eighteen to nineteen inches in height each month. Its wood appears to be hard, close in the grain, and it is largely used in the construction of quays, bridges, and railways. This tree seems to do so well on the southern side of the Mediterranean that we think its culture ought to be successfully attempted in the south of Spain, in Sardinia, in Sicily, and the southern parts of Italy. In districts subject to heavy winds it requires for some years-owing to its rapid growth-some protection, but in places sufficiently warm for it, it ought to repay well for any little extra care it might be found to need,

Among the few species that we noticed that did not succeed in these gardens, we may mention the Cedrus deodara; but Casuarina equisetifolia was flourishing, and one tree of Araucaria excelsa was about sixty feet in height, and measuring a little over nine feet in circum. ference at its base.

The object of the Society in keeping up these Gardens is, as we said, to introduce into Algeria all useful and ornamental plants likely to grow there. In addition they grow enormous quantities of young palms and other ornamental plants for exportation to Europe, and some few plants interesting to the botanist for exchange with other establishments. In a place so favoured by nature and so easily accessible to Europe, it would be, we venture to think, well worth the while of the director of these Gardens to considerably enlarge the last portion of the Society's design. How many tropical plants are yet unknown to the large collectors of Europe, and what a vast percentage of deaths occur among the collections sent from the tropics at any season of the year to our shores! But with Gardens like these at Algeria, situated on the sunny side of the Mediterranean, to act as a halfway. house, the resources of the Botanical Gardens of establishments of the North would be indefinitely in creased. Another purpose for which these Gardens might be made most useful is for forming a collection of speci mens of plants or fruits of economic interest. Many of the fruits, stems, &c., which ripen in these Gardens as easily as cherries or potatoes with us, are not to be surn in some botanical collections, and are not, in Europe at least, to be purchased. How gladly would some botanist buy such as we here refer to if they were on sale, say at the depôt of the Algerian Society in Paris; and the expense of putting up such in salt and water would be a mere nothing. The same remarks would apply in many cases to portions of the roots of remarkable genera, and also to flowers. In calling attention to these Gardens, we venture to suggest these hints to their well-known director, and also to that indefatigable botanist who, more than any other, now represents science in connection with the Algerian Society, Prof. Durando of Algiers. E. P. W.