THURSDAY, FEBRUARY 29, 1872

SCIENCE STATIONS

dependent isolated existence.

There is too great a want

of community in our English Universities and Colleges especially in matters of natural science. There is one zoology at Oxford, another at Cambridge, another at Jermyn Street, and these three have miserably little dealings with one another. What immeasurable good

that the article by Dr. Dohrn in a recent number of NATURE on "Zoological Stations" has attracted considerable attention among thoughtful men. We may, indeed, congratulate zoologists that so important a task has been taken in hand by one in every way so well fitted to accomplish it; and it will gratify our readers to learn that the cheery energy and bright enthusiasm of the German anatomist is fast overcoming the obstacles which his scheme naturally met with in the indolent city of the South, whose lands are so rich in classic ruins, and seas so full of Darwin-speaking embryos. At the risk of spoiling a good work we venture to add to his remarks some further suggestions, confining ourselves, however, to one or two points.

In the first place, we will be bold enough to express the doubt whether it will be advisable to separate so entirely, as Dr. Dohrn recommends, the stations in England from the work of teaching. The establishment of such stations will be rendered infinitely easier if they can in any way be made self-supporting. Dr. Dohrn hopes, if we understand him rightly, to pay the expenses of the Naples station out of the fees of the Gentile sightseers, who will be allowed to stroll about in the outer court of his embryological temple. There can be no such hope for any like English temple. Yet a very considerable share of the necessary funds might without difficulty be raised, and a Philistine British public might be made to believe that it was getting its money's worth for its money, if the work of teaching, which is palpable, which may be measured and valued, and for which a receipt in full may be given, were to go on hand in hand with the immeasurable and invaluable work of original inquiry. There would thus naturally grow up around the station a school of sound zoology; otherwise there would be great danger of its becoming a resort of ambitious privat-docents anxious chiefly to find a notochord where nobody had found it before, or a home of some narrow zoological clique.

Much might be said for the establishment somewhere on our British coasts of such a school of zoology on the theory of a geographical distribution of scholarship, and the existence of particular habitats best suited for particular branches of learning. Sufficient foundations for such a theory are at hand. It is easy to understand why Edinburgh, with her sea close by, has raised so many brilliant zoologists. We can see why Manchester in the past and in the present has done so much for chemistry. And, to look at the matter from another point of view, one gets a glimpse of the reason why high mathematics flourish at Cambridge, when one gazes at her fenny flats, where, if the conception of three dimensions be once reached, that of four is soon gained, and feels the fogs and mists which wash out of the mind everything that is not held fast by formulæ. The natural habitat for an English school of zoology is surely some bright spot on our southern coast.

or for a term, the zoological students of all the Universities might mingle together with mutual diffusion of ideas! * The mere opportunity of material would be a great thing: the Cambridge student would lift his ideas above the line of beautifully prepared vertebrate skeletons, the Oxford man would benefit by the change of diet from Anodon and Astacus, and the London man would learn to see actual things instead of reading about them in books. But the greatest thing of all would be the catholic enthusiasm for biological learning, which such an institution could not fail to generate and foster.

Another remark which we would wish to make takes on somewhat the shape of a complaint against Dr. Dohrn, that he has confined to one science ideas which should properly belong to all the sciences of observation. It is well to have a Biological station, but it is far better to have a station at once Biological, Astronomical, and Meteorological. Let us imitate Dr. Dohrn in giving our views a concrete form. The eclipse party on their outward, and even on their homeward voyage, cannot fail to have been struck with the bright clear air of the North Red Sea. There is the very land of observation. It is impossible for any one with a fragment of a mind within him to sojourn on those delightful shores, where the eye rejoices in its power, where the air helps vision instead of hindering it, where the water is as clear and transparent as the air elsewhere, without the desire springing up to be a naturalist by day and an astronomer by night. And this blessed region is now little better than a week's journey from the fogs of London. Nothing could be easier than to establish at no great expense a Science Station at some spot on the shores of the Red Sea, a little south of Suez. Suez itself is for many reasons undesirable, but the little village of Tor suggests itself as being a very suitable neighbourhood. There would be comparatively little difficulty in getting supplies, or in going and coming to and fro. The naturalist, the astronomer, the meteorologist, with the Palestine explorer as an occasional helpmeet, might spend here a winter, or rather many winters, in which pleasure and profit would be running a hard race together.

We cannot help thinking that such an idea has only to be mooted to be at once caught up and set in action. The outlay of the initial building and arrangements need not be heavy, while the yearly expenditure might be kept within comparatively narrow limits. Such an undertaking is one which Government might justly take in hand, but it is also one which private liberality might largely aid, and to which contributions might come from the funds of our ancient seats of learning. In any case we fairly think it is matter deserving serious attention, and as such we leave it to our readers.

VOL. V.

T

BURTON'S ZANZIBAR Zanzibar: City, Island, and Coast. By Richard F. Burton. In 2 vols. (London: J. Murray, 1872.)

IN

N these two bulky volumes Captain Burton gives us, after a lapse of thirteen to sixteen years, a narrative of his adventures and explorations in the island of Zanzibar, the neighbouring smaller islands, the adjacent coast of the mainland, and the Highlands of Eastern Africa intervening between the coast and the great Victoria N'yanza, the publication having been delayed by a series of remarkable accidents. As in everything else that Captain Burton has written, the volumes are full of graphic delineations of the natural features and inhabitants of the country, combined with not a few details of a personal character which have not the same interest for the general reader. In 1856 Captain Burton laid before the Royal Geographical Society his desire once more to explore Equatorial Africa; a committee was formed to assist him in his undertaking, a grant of 1,000l. was obtained from Lord Clarendon, then Secretary of State for Foreign Affairs, and on September 16th the enterprising traveller received formal permission, "in compliance with the request of the Royal Geographical Society, to be absent from duty as a regimental officer under the patronage of Her Majesty's Government, to be despatched into Equatorial Africa, for a period not exceeding two years, calculated from the date of departure from Bombay, upon the pay and allowances of his rank." On December 26th in that year he landed at Zanzibar, the first view of which is thus attractively described :—

"Earth, sea, and sky, all seemed wrapped in a soft and sensuous repose, in the tranquil life of the Lotos-caters, in the swoon-like slumber of the Seven Sleepers, in the dreams of the Castle of Indolence. The sea of purest sapphire, which had not parted with its blue rays to the atmosphere-a frequent appearance near the equator lay basking, lazy as the tropical man, under a blaze of sunshine which touched every object with a dull burnish of gold. The wave had hardly energy enough to dandle us, or to cream with snowy foam the yellow sandstrip which separated it from the underwood of dark metallic green. The breath of the ocean would hardly take the trouble to ruffle the fronds of the palm, which sprang like a living column, graceful and luxuriant, high above its subject growths. The bell-shaped convolvulus (Ipomaa maritima), supported by its juicy bed of greenery, had opened its pink eyes to the light of day, but was languidly closing them, as though gazing on the face of heaven were too much exertion. The island itself seemed over-indolent and unwilling to rise; it showed no trace of mountain or crag, but all was voluptuous with gentle swellings, with the rounded contours of the girl-negress, and the brownred tintage of its warm skin showed through its gauzy attire of green. And over all bent lovingly a dome of glowing azure, reflecting its splendours upon the nether world, whilst every feature was hazy and mellow, as if viewed through 'woven air,' and not through vulgar atmosphere."

A residence, however, of some months in the island by no means established the impression which its first appearance might convey, of its being a terrestrial paradise. The city of Zanzibar itself is a miserable, ill-built place, foetid and unhealthy; while the personal appearance and habits of the natives are repulsive in the extreme. The climate is remarkably uniform as to temperature, the result of nine months' observation showing a range of

18-19° F. only. The medium temperature of January is 83.5°; of February, the hottest month in the year, about 85°; and the mean gradually declines till July, the coolest month, 77°. The mean average of the year is between 79° and 80°. The barometer is almost uniformly sluggish and quiescent, a few tenths above or below 30 in. representing the maximum variation, even under the influence of a tornado. Uniform, however, as is the temperature, the degree of humidity of the atmosphere varies excessively. At certain seasons the amount of moisture exceeds that of the dampest parts of India, and the annual rain-fall is in some years double that of Bombay, varying from 100 to 167 inches. The Msika, or principal rainy season, lasts from April to June; the island is enveloped in a blue mist, and the interior becomes a hot-bed of disease; the hair and skin are dank and sodden; shoes exposed to the air soon fall to pieces; paper runs and furniture sweats; the houses leak; books and papers are pasted together; ink is covered with green fur; linens and cottons grow mouldy; and broadcloths stiffen and become boardy. This excess of damp is occasionally varied by the extreme of dryness. During the prevalence of the dry wind cotton cloth feels hard and crisp, books and papers curl up and crack, and even the water is cooled by the excessive evaporation. Earthquakes are all but unknown in Zanzibar, a single shock being recorded as having been felt in 1846. Tornadoes are frequent, but the cyclones and hurricanes of the East Indian islands rarely extend to this coast. During fourteen years there was but one tourbillon strong enough to uproot a cocoa-nut tree.

The prosperity of Zanzibar depends almost entirely on its vegetable productions, and chiefly on the cocoa-nut and the clove. The former supplies the natives with nearly all their wants-food, wine, spirit, cords, mats, strainers, tinder, firewood, timber for houses and palings, boats and sails; and Captain Burton calculates that in 1856 12,000,000 nuts were exported for the soap and candle trades. The sugar-cane might be grown to great advantage, but for the constitutional indolence of the inhabitants. Cotton has been tried, but does not thrive; and coffee has not been cultivated to any extent. The fruits in greatest request by the islanders are the mango, the orange, the banana or plantain, the pine-apple, and the bread-fruit— all, however, with the exception of the banana and an inferior kind of orange, being introduced exotics; the pine-apple has become perfectly naturalised. The most important production of the island is the clove, which does not, however, produce crops comparable to those of the East Indies either in quantity or quality, owing to want of skill and intelligence in its cultivation. The copal of commerce is obtained chiefly from the neighbourhood of Saadani, on the opposite coast of the mainland; and Captain Burton entirely confirms the account of its production already communicated to the Linnean Society by Dr. Kirk, that it is a gum, or resin, exuding from wounds in the stem of a small tree or large shrub (Hymenæa verrucosa) belonging to the order Leguminosæ.

Captain Burton's first expedition from Zanzibar was to the smaller island of Pemba, lying to the north, and thence to Mombasah, on the coast 4° south of the line, the capital of Northern Zanzibar, the best harbour on the Zanzibar coast, land-locked by coral islands. The town itself is built on the largest of these islands, where the climate is

hotter, drier, and healthier than that of Zanzibar. Here he did not attempt to strike inland, the weather and the hostility of the native tribes being unfavourable, but returned along the coast southwards to Pangani, and thence inland to Fuga, the capital "city" of Usambara, in the Highlands of Eastern Africa. In order to gain a complete knowledge of the Zanzibar coast, he also paid a visit to the island and port of Kilwa, situated beneath the ninth degree of south latitude. Here are the remains of an ancient town of considerable size, with respect to which many legends are current among the natives; but the gradual sinking of the coast has rendered the ancient site uninhabitable. Although at the present time a miserable and fœtid collection of squalid huts, Kilwa was found in 1500 by the Portuguese a town of great prosperity, the capital of Southern Zanzibar, and ruling the coast as far as Mozambique and Sofala; but the curses of European wars and the slave-trade have desolated the once thriving country. Captain Burton does not think very highly of the so-called "free labour" system, which he terms "the latest and most civilised form of slavery in East and West Africa."

The most important expedition made by Captain Burton was, however, that undertaken between 1857 and 1859 to Kazeh in the Ukimbu district, upwards of 500 miles from the coast, and about 2° south of the southern shore of the great Victoria N'yanza, in company with Captain Speke. But as this journey has already been illustrated in his own "Lake Regions of Central Africa," and the country has been further described by Colonel Grant and Captain Speke, he does not again enter into details respecting it; but thus sums up what he considers its geographical results :-" That the Boringo is a lake distinct from the 'Victoria N'yanza' with a northern effluent the Nyarus, and therefore it is fresh water; that the N'yanza, Ukara, Ukerewe, Garawa, or Bahari y a Pili, is a long narrow formation, perhaps thirty miles broad, and 240 miles in circumference, and possibly drained to the Nile by a navigable channel; that the N'yanza is a water, possibly a swamp, but evidently distinct from the two mentioned above, flooding the lands to the south, showing no signs of depth, and swelling during the low season of the Nile, and vice versa; and that the northern and north-western portions of the so-called 'Victoria N'yanza' must be divided into three independent broads or lakes, one of them marshy, reed-margined, and probably shallow, in order to account for the three effluents within a little more than sixty miles."

The botanical results of this journey are about to be illustrated by Colonel Grant, in a magnificent volume, to be published by the Linnean Society, which it is understood will be illustrated by 600 plates, the cost of which will be defrayed entirely by the gallant author.

One chapter is devoted to a sketch of the labours of Captain Burton's old comrade, Captain Speke. Though tribute is here paid to his many excellent qualities, we regret to be again introduced to the details of the estrangement which grew up between the explorers, culminating at the meeting of the British Association at Bath, when the two companions in arms met as

strangers, advocates of two rival "Nile-theories,"

as to the origin of the Father of rivers.

In the Appendices, Captain Burton gives some useful

details of the meteorology, commerce, &c., of Zanzibar. A well-executed map helps to illustrate the author's journeys, without a constant reference to which the narrative is by no means clear; but we cannot commend the style in which the woodcuts interspersed here and there are executed.

OUR BOOK SHELF

Deschanel's Natural Philosophy. By Prof. Everett. Part III., Electricity and Magnetism. (London and Edinburgh Blackie and Son.) IN the Preface by the translator of the present volume, it is said, with much truth, that "the accurate method of treating electrical subjects, which has been established in this country by Sir W. Thomson and his coadjutors, day's electromagnetic work appears still to be very imhas not yet been adopted in France; and some of Faraperfectly appreciated by French writers." Accordingly we find that the translator has added a considerable amount of matter, and more especially two important chapters, one on the electrical potential and lines of electric force, and the other on electrometers, together Everett has thus considerably improved a book, which, in with an appendix on electrical and magnetic units. Dr. its original form, was already a good one. The ordinary branches of the subject are unfolded, the plates are good, and the explanations are full and clear. The portion devoted to magnetism is in this, as apparently in all such general treatises on natural philosophy, considerably the relate to terrestrial magnetism. most defective part, and especially in the sections which The whole of that question is most insufficiently dealt with. The treatment of the secular changes in the magnetic elements is confined to twelve lines, where it is said that "declination and dip vary greatly, not only from place to place, but from unlearned reader would be led into the error that intensity time to time;" but from which we should expect that the is uniform. Then, again, the vast subject of changes in the elements, such as are not secular, is confined to one short paragraph, headed "Magnetic Storms"! intrinsic importance of the subject of terrestrial magnetism, and the great and increasing interest attaching to it, no less than the extreme beauty of many of its investigations and results, entitle it to a much larger notice than the very imperfect one in this volume. The chapter on the Telegraph contains useful matter, and especially a description of an autographic telegraph, an instrument which, while interesting and ingenious, has not often found its way into such treatises. We miss such points as how to find the locality of a fault in a telegraph wire, which we might the more expect to see treated of when we consider the full explanation which is given of Ohm's laws, and when we see such elaborate details as to some telegraphic instruments as are entered into in the chapter in question. The chapters on the heating effects of currents, and on electrolysis, are clear. The question of electromotive force, entered into more fully; and, generally, from the character and of the means of determining it, might have been of the chapter on the potential, we might have expected to see a little more introduced concerning points which may be elucidated by the application of the principle of the conservation of energy. JAMES STUART

The

Medizinische Jahrbücher, herausgegeben von der k. k. Gesellschaft der Ärzte, redigirt von S. Stricker. Jahrgang 1871. Heft iv. Mit 4 Holzschnitten. (Wien: 1871.)

THIS part, which concludes the first volume of Stricker's Jahrbuch, contains: (1) Researches on the Inorganic Constituents of the Blood, by Adolph Jarisch. Jarisch gives the details of an improved method by which blood can be

In Verdeil's treatise, the amount of ashes of fresh blood is stated to be on the average 6:45 per cent. Jarisch points out that this must be an error of the press, his own results giving only o'864 per cent., a difference that is too great to be regarded as an error of analysis. 2. An essay on the Centres of Vascular Nerves, by Dr. Soboroff. In this paper Dr. Soboroff shows from the results of experiments performed on frogs that the nerves supplying the vessels of the web of the foot proceed from the spinal cord, and run into the sciatic nerve. 3. On the presence of Fungi in the Blood of Healthy Men, by Adolph Lorstorfer. Lorstorfer drew blood from the fingers of eleven people who considered themselves in perfect health with every precaution to avoid contamination with dirt, and examined the specimens daily with a Hartnack microscope, ocular 3, objective 10. During the first two days he observed nothing remarkable, except in some cases a few scattered groups of small granules. On the third day similar groups were always found, though still scattered. The granules were of equal size, considerably larger than those of the colourless blood corpuscles, but without any definite arrangement. On the fourth day they had increased in size, and were arranged in groups of four, so as to resemble the wellknown Sarcina ventriculi. On the fifth day the granules had slightly increased in number and size, but after this date no change was observable up to the tenth day, when the preparations became unserviceable. Lorstorfer thinks his experiments render it probable that the germs of Sarcina ventriculi exist in the blood as a natural condition. There are three other papers, but they are all of a purely professional nature. One being by Hofmokl on Resection of the Upper and Lower Jaw: one by Bresslauer on Typhus and one by Popoff on Pneumonia.

:

LETTERS TO THE EDITOR

H. P.

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

Development of Barometric Depressions

I HAVE only just had my attention called to the critique on "The Laws of the Winds prevailing in Western Europe," in NATURE of Jan. 11, which I have seen to-day for the first time. Though it is now rather late to do so, I may perhaps be permitted to point out some unintentional misrepresentations of my views into which the writer appears to me to have fallen.

He considers it improbable in the extreme that the course of baric depressions should be regulated "by one law" in intratropical, and by "a totally distinct law" in extra-tropical regions of the globe. I pointed out (pp. 40, 41) that in temperate latitudes the general distribution of atmospheric pressure commonly tends to transfer local depressions in an eastward direction; while the influence of precipitation resulting from the mean distribution of solar heat propagates them in the same direction. Since the reversal of pressure-distribution which accompanies polar periods only retards the eastward progression, I drew the

conclusion that, in temperate latitudes, the most important of the two factors of the progression is the influence of precipitation, and accordingly I devoted the first part of my work to this, with the promise (which I hope shortly to redeem) that the motive effect of the general pressure-distribution shall be described in Part II. All this your reviewer ignores. Had I been engaged in a discussion of the tropical cyclones, I should have proceeded in an inverse order; since the most important factor of their westward progression appears to be the mechanical influence of the distribution of surrounding pressures. It is, however, important to observe that as in temperate, so in tropical latitudes, these two influences are commonly coincident in direction. In the West Indies, e.g.-at those periods when cyclones prevail-mean temperatures are lower on the south, or left, than on the north, or right, of their course; and a similar remark applies, mutatis mutandis, to the typhoons of the Indian and China seas.

Briefly, my position is this. The influence of the general distribution of temperatures, and that of the general distribution of pressures, may be practically regarded as two forces, A and B, from which the progression of local depressions results. Both of these commonly act in the same direction-in temperate latitudes producing eastward, and in tropical westward, progression. But of these A is the preponderating influence in temperate, B in tropical latitudes; partly because the influence of precipitation on the surface-currents increases with diminution of temperature, and partly because the currents resulting from the general distribution of pressures are far more constant and of vastly greater extent, in proportion to the extent of the cyclones, in tropical than in temperate latitudes. I am convinced that the attempt to simplify the rules which regulate the progression of depressions by striking out either of these factors, or by the substitution of J. K. L.'s single law, will meet, as it has hitherto met, with

failure.

Your reviewer also ignores what I have said (pp. 28, 29) as to the occurrence of heavy precipitations unproductive of baric depression, and thinks it necessary to travel to Khasia or to the Himalayas to find illustrations of a truth which it was never intended to deny. Every one conversant, as he considers me to be, with the meteorology of Western Europe alone, is aware that heavy and extensive precipitation not uncommonly occurs without producing retrograde circulation (and sometimes with generally increasing pressures), where antecedent atmospheric conditions do not favour such developments. The reviewer concedes that the immense precipitation in the Himalayas "probably causes a very great barometric depression; " a concession which is not to be accepted, both because such a reference to antecedent probabilities is inapplicable to empirical science, and because the fact itself may be denied. But supposing this great Himalayan depression to exist, and no retrograde circulation (as J. K. L. maintains) to be developed around it, his discovery of a region in which "Ballot's rules" are contravened, is indeed one of no small importance.

Into the wide question of the influence of the earth's rotation I will not here enter, further than to remark that the hitherto admitted universality of the rules connecting the direction of all atmospheric currents with the distribution of surrounding pressures, and the variation of these rules in the two hemispheres, appears to have been satisfactorily accounted for by attributing it to the earth's rotation; while it has never been, with much plausibility, traced to any other cause or combination of causes. Hereford, Feb. 17

W. CLEMENT LEY

Zoological Nomenclature

IN the President's address to the Entomological Society of London recently given by Mr. Wallace, one of the points most fully discussed is the rules of zoological nomenclature. These rules are undoubtedly of very considerable, though indirect, importance to science, and it is not very satisfactory to find that great divergence of opinion as to what these rules are, or should be, still prevails amongst recent describers and cataloguers.

Some years ago I was entrusted by the Entomological Society with the task of preparing a synonymical catalogue of the Coleoptera of our islands, to be published under the auspices of the Society; my attention, therefore, has necessarily been directed to the questions under discussion in this matter, and I will here state the conclusions to which I have come.

Ist. That a committee to frame and publish laws on zoological nomenclature is not to be desired. Such committee would have

no power whatever to enforce the laws it might make, and could not be expected to put an end to discussion on these points. The knot must be untied, not cut.

2nd. That the binomial system of nomenclature should not be arbitrarily considered to have commenced at any given date; but that recognisable names in all works in which this system is methodically employed should be used according to the rule of priority.

3rd. That it is not necessary to suppress a generic name in zoology because it has been previously used in botany (or vice versa); but that it is much to be regretted that any generic name should thus be in double use, and it should always be made matter of reproach to an author that he has committed an act of this nature.

4th. That names must be Latin to the extent that renders them capable of being written or used in scientific Latin; but that classical emendations beyond this are entirely inadmissible ; no line except this can be drawn between emendation, alteration, and total suppression. The laws of classical languages have, per se, no more right over scientific nomenclature than has the Hindoo language. As regards the much talked-of " 'Amphionycha knownothing," it should be latinised in the simplest manner, as Amphionycha knownothinga; and I would further suggest that its barbarian author be well hissed whenever he ventures to show his face in a scientific assembly.

5th. That as regards placing an author's name after a species, the name so placed should always be that of the first describer of the species; not because he has any right in the matter, but as an additional means of certainty, and as a security against change.

6th. That the specific name is the name of an object, and therefore a noun, and should be changed in gender, or any other manner, when removed from one genus to another.

7th. That it is very undesirable to use the same specific name in two closely-allied genera; but that where this has been done already no alteration should be made till the two names actually come into collision on account of the two genera being united as one genus. Surely to act otherwise is like cutting one's throat for fear somebody else should do it.

8th. That as regards placing an author's name after a genus, the name so placed should be that of the author who established the genus in the sense in which it is actually used. Carabus of Linnæus included all the insects now comprised in the family Carabida, at present divided into several hundreds of genera. To write, therefore, Carabus Linn., when we mean something entirely different, may be usual but is not desirable.

I may add, that I consider it useless to expect a perfectly stable zoological nomenclature, until zoology itself is complete and perfect; but that in order to reduce changes to a minimum, classical and other secondary claims must not be allowed any great importance.

Thornhill, Dumfriesshir

Deep-Sea Soundings

D. SHARP

IN reference to the very interesting article in NATURE for February 22, "American Deep-Sea Soundings,” may I be permitted to make the following remarks:-It is there stated that the water-collecting cylinder is apt to lead to incorrect conclusions in regard to the gaseous ingredients of sea water obtained by its means from great depths, owing to the escape of a portion of the gases when the pressure is relieved by the cylinder being drawn to the surface. As a member of the Porcupine expeditions of 1869 and 1870, I had nearly eight weeks' constant daily experience in the examination of samples of abyssal water thus obtained, and I believe that I was the first to adapt the gas analysis apparatus of the late Prof. W. A. Miller to the exigencies of a laboratory on board ship. The general result of these experiments for 1869 will be found as an appendix in No. 121 of the Proceedings of the Royal Society. My object in writing now is to point out that if there were such an escape of gaseous ingredients as is indicated above, the abyssal water would be so saturated with them at the ordinary atmospheric pressure (ie. after the sample was removed from the water cylinder in the laboratory), that the least elevation of temperature would be sufficient to cause a further quantity to be given off. This, however, never was the case, since I invariably noticed that there was no appearance of bubbles of gas, until the water had

been heated above 120° Fahr., and frequently still hotter. I may add that the only samples of water which appeared saturated with gaseous ingredients were those taken at the surface, afte several hours of strong wind. I must confess that after giving a good deal of thought to the subject, and conversing with friends whose knowledge of physics is far greater than mine, who agree with my view of the matter, I am unable to see any reason why we should expect to find any greater quantity of gaseous ingredients in abyssal than in surface water. No doubt, if the excess were there the enormous pressure would retain it, but where is the source of the supply of the supposed excess? I have never seen a satisfactory answer to this question. The solvent is exposed to excessive pressure, but the gases to be dissolved in it are not, unless there is any evolution of gas at those depths. It is probable that this abyssal water was at some point in its circulation near the surface, when an interchange would take place between some of its dissolved carbonic acid and the oxygen of the atmosphere. And it appears to me that it is only when the particles of sea water are near the surface, and exposed to no excess of pressure, that they dissolve their gaseous ingredients, which are afterwards modified in their composition by the animal life on the sea bottom. WILLIAM LANT CARPENTER

Clifton, Bristol, February 26

Snow at the Mouth of a Fiery Furnace

It would be interesting to ascertain the temperature of the saltatory drops noticed by Mr. H. W. Preece. Sudden and excessive evaporation may have produced actual congelation. HENRY H. HIGGINS

ON THE SPectrum of THE ATMOSPHERE

DURING the voyage out to India of the Eclipse Ex

pedition, I took every opportunity of observing carefully the spectrum given at sunrise, compared with that at sun-high, and obtained the following results, which, though poor in themselves, will show the wide field open for further research.

When leaving England, and for some way into the rise extended generally from about B in the red to near Mediterranean, the length of the spectrum as seen at sunG in the violet. Great differences were, however, presented in the absorption-lines according to the state of the weather, or perhaps rather according to the state of the sky when the sun rose.

If the sun rose among yellow tinted clouds, the absorption bands about B, C, between C and D, and near D, were exceedingly well defined; at the same time the blue end did not extend so far as usual, showing that there was more absorption of the blue, while probably the greater quantity of aqueous vapour in the air reflected the red generally changed to a rosy red shortly after sunrise. and yellow rays. In these cases the tint of the clouds

A clear sunrise, on the contrary, showed an extension of the violet end, whilst the aqueous bands at B, C, and D were less defined, as if the red and yellow light were not so strong to show them out by contrast.

On passing through the Suez Canal and down the Red Sea the spectrum was shortened at both ends, leaving from little beyond C to a third from F to G; this would seem to show a general absorption going on in the atmosphere from some cause, probably light dust in the air. This idea is strengthened by the beautiful purple colour of the distant mountains, as if, though the violet rays were greatly absorbed, the red rays were so to a less degree, whilst the want of aqueous vapour allowed nearly all the yellow rays to be transmitted.

When clear of the Red Sea in the Indian Ocean, the blue became greatly reduced, and the red end extended to A; the aqueous bands were very strong indeed, so much so that on two mornings D1 and D2 could hardly