blowing from the north-west, and we should be more or less in the teeth of it. Accordingly we bore to the southwest, so as to get the mountain between us and the wind. Even thus the ascent was very trying; violent gusts of wind sometimes caught us, and volcanic sand and small stones were blown across our path. On arriving at the summit I saw that the small cone, which, when I had seen it a year before, was no larger than an iron furnace, had in the course of the year increased both in bulk and height. It now reaches to a height of more than fifty feet above the rim of the great crater, and very large masses of cinders have accumulated around it. Moreover, it has almost filled up the great crater of 1872 by masses of lava and scoria. When the crater gets quite filled up, and the throat of the small cone choked with lava, we may look for a grand paroxysmal outburst like that of 1631 or 1872.

The cone of November, 1878, was giving off dense volumes of white steam and reddish smoke. Its dynamic

activity was considerably greater than it had been the year before, and large masses of scoriæ were ejected to a considerable height at frequent intervals. The lava surged up within the throat of the cone very frequently, from the sudden disengagement of vapours within the seething mass. Near the base of this cone a small hole, apparently about five feet in diameter, had opened to give vent to lava, the great pressure of which had prevented it from rising high in the cone, and had caused the latter to give way at the point of least resistance. Two streams had recently flowed from this; a small one towards the south-west had not reached the rim of the crater; it was red-hot, not more than two inches beneath the surface, but we ran over it with no worse result than scorching our boots. The other stream-the main stream of December 17, 1879-(vide the accompanying woodcut) had flowed towards the north-west, and had found its way into the Atrio del Cavallo. As we watched the lateral bocca, the lava within it

became furiously agitated; it was thrown up three or four feet above the opening, exactly in every respect resembling small geysers which I have seen at Reykir, and at Haukadalr in Iceland; and presently the liquid mass filled completely the bocca, and flowed over as a very fluid stream along the course of the lava of December 17. By the time we reached the Observatory again, the stream, which was about twenty-five feet wide, was seen to have flowed over the rim of the crater; by ten o'clock the same evening it had flowed half way down the great cone, and by I A.M. the next morning it had reached the Atrio del Cavallo, presenting an appearance almost precisely similar to that of the stream of December 17. Dense clouds of vapours marked the course of the stream; a good deal of hydrochloric acid was disengaged; and the icy tramontana in blowing over the liquid mass was converted into an unbearably hot furnace-breath. The next day (January 14) the energy of the mountain appeared to have slackened; and on the morning of the

15th a good deal of snow fell, and the course of the lava stream was well shown by a jet black line through the snow.

The lava is very leucitic, and is somewhat similar to that of 1871. The fumeroles have afforded copious sublimations of chlorides and sulphates, in which the spectroscope has revealed the presence of lithium and thallium. The gases evoked nearest to the centre of activity are sulphurous acid and hydrochloric acid. Carbonic acid still appears in some of the remoter sources of emanations.

Prof. Palmieri, in the MS. to which I have alluded above, writes as follows:-"This long and mild eruptive period, in which Vesuvius has become a mere imitator of Stromboli, will not in our opinion come to an end without displaying more decided activity. The whole history of Vesuvius, though its greater eruptions only have been chronicled by ancient writers, may be divided into periods of activity, with occasional phases of violence, and short

intervals of rest. And the greatest eruptions have generally indicated the last phase of long periods of moderate activity, periods that escaped the notice of the early writers. The true history of Vesuvius could not have been written until after the establishment of the present observatory. The seismograph of the observatory gives the most accurate indications of the eruptive attempts (dei conati eruttivi) of the mountain and of the degree of its dynamic activity."

Two other facts require to be alluded to before we close the history of Vesuvius in 1879. The one is the alleged discovery by Prof. Scacchi of a new element in the yellow and green incrustations found on the lava of 1631. The former of these he believes to be vesbiate of aluminium, the latter vesbiate of copper. The element is named Vesbium, from an old name of Vesuvius mentioned by Galen. The subject requires further investigation before we can assert with any confidence that a new element has been discovered.

The second fact is that the Vesuvius railway, from the base to the summit of the cone, more than 1,000 feet, with an average slope of 32°, has been commenced, and is progressing thus far favourably. The work is slow, but labour is cheap; we saw fifteen men dragging a single beam of wood up the cone. We are inclined to regard the whole thing as a very hazardous commercial undertaking. For to begin with, if the company charges 20 lire for each ascent, it will be long before a fair interest can be paid on the original cost and the working expenses. Moreover, the property is insecure, a stream of lava on the south-west side of the cone would destroy the line at once, and a violent earthquake would throw all the machinery out of gear. G. F. RODWELL

“COM

THE CRAYFISH1

mon sense at its best, that is, rigidly accurate in observation, and merciless to fallacy in logic." In the preceding quotation Prof. Huxley is (in a legitimate and intelligible way) using the word "science" in place of "that quality of mental activity by which science is produced." Immediately afterwards he speaks of science as the product of certain mental operations, in a passage which possesses great beauty whilst setting forth fundamental but neglected truths as to the source and scope of human knowledge. "In its earliest development knowledge is self-sown. Impressions force themselves upon men's senses whether they will or not, and often against their will. The amount of interest which these impressions awaken is determined by the coarser pains and pleasures which they carry in their train or by mere curiosity; and reason deals with the materials supplied to it as far as that interest carries it, and no farther. Such common knowledge is rather brought than sought; and such ratiocination is little more than the working of a blind intellectual instinct. It is only when the mind passes beyond this condition that it begins to evolve science. PP

'OMMON and lowly as most may think the crayfish, it is yet so full of wonders that the greatest naturalist may be puzzled to give a clear account of it." These words from von Rosenhof, who in 1755 contributed his share to our knowledge of the animal in question, are cited by Prof. Huxley in the preface to the careful account of the English crayfish and its immediate congeners, which forms the latest volume of the International Scientific Series. The book is not designed for "general readers," those somewhat luxurious but presumably intelligent persons for whom so much scientific knowledge is chopped and spiced at the present day. It is, as we gather from the author's statement, intended as an introduction to serious zoological study, for those who will turn over its pages, crayfish in hand, and carefully verify its statements as to details of structure with scalpel and microscope. To these and also to those who are already well versed in crustacean anatomy, the book will have great value and interest; to the latter more especially, as showing how in the careful study of one organism we are "brought face to face with all the great zoological questions which excite so lively an interest at the present day," and as an exhibition of that "method by which alone we can hope to attain to satisfactory answers of these questions."

A crayfish is treated in this volume from the point of view of "science," and in the first pages we have some excellent observations (recalling earlier remarks of the author's in the same sense) directed to clearing up that mystery which good people will insist on throwing around that ever-more-widely-heard term. "Common sense," says Prof. Huxley, "is science exactly in so far as it fulfils the ideal of common sense; that is, sees facts as they are, or, at any rate, without the distortion of prejudice, and reasons from them in accordance with the dictates of sound judgment. And science is simply com

The Crayfish: an Introduction to the Study of Zoology." By T. H.

Huxley, F.R.S. (London: Kegan Paul, 1880.)

FIG 1.—Astacus fluviatilis.-The third or external maxillipede of the left side (x3)., lamina, and br, branchial filaments of the podobranchia; crp, coxopolite; cxs, coxopoditic setæ; bp, basipodite; er, exopodite; ip, ischiopod.te; mp, meropodite; cp, carpopodite; p, propodite; dp, dactylopodite.

When simple curiosity passes into the love of knowledge as such, and the gratification of the æsthetic sense of the beauty of completeness and accuracy seems more desirable than the easy indolence of ignorance; when the finding out of the causes of things becomes a source of joy, and he is accounted happy who is successful in the search, common knowledge passes into what our forefathers called natural history, from whence there is but a step to that which used to be termed natural philosophy, and now passes by the name of physical science.

"In this final state of knowledge the phenomena of nature are regarded as one continuous series of causes and effects; and the ultimate object of science is to trace out that series, from the term which is nearest to us, to that which is at the farthest limit accessible to our means of investigation.

"The course of nature as it is, as it has been, and as it will be, is the object of scientific inquiry; whatever lies beyond, above, or below this, is outside science. But the philosopher need not despair at the limitation of his

field of labour; in relation to the human mind nature is boundless; and though nowhere inaccessible, she is everywhere unfathomable."

It is, then, with the object of arriving at a satisfactory conclusion as to the crayfish's place in nature, and to educe from the study of it such conclusions as may tend to throw light on the place in nature of other living things, that the reader is supposed to enter upon the consideration of the facts which Prof. Huxley lays before him.

No pains have been spared in the illustration of the text-the woodcuts (eighty-one in number) reflecting great credit both on the artist for his skill, and on the publisher for his enterprise. We have, after a general disquisition on the natural history of the crayfish (by no means the least interesting in the book), two devoted to

with lobsters and prawns, and it is explained how the amount of likeness and difference between these various but closely similar animals may be expressed by the method of classification in groups. Finally we have a chapter on the geographical distribution of crayfishes, and the facts therein narrated, together with those adduced in the previous chapter, enable the author to sketch the probable pedigree of crayfishes, that is, to refer them to their causes, viz., to the action of such physical agencies as flowing rivers, land and climatic barriers, brought to bear upon successive generations of the offspring of marine lobster-like ancestors which had a wide distribution in the earlier tertiary and later mesozoic periods, and before taking to fluviatile life had separated into two dis

FIG. 2-Astacus leptodactylus (after Rathke, nat. size). the consideration of the crayfish as a mechanism-in fact its physiology. Here a good deal of the anatomy is given and considered from the point of view involved in the question "What does it do?" Then we have the morphology of the English crayfish-the structure and development of the individual minutely set forth, even each joint of each leg, and each tuft on each gill, and each group of hairs, being described and figured. We are enabled by the courtesy of the publishers to reproduce one of these highly-finished engravings representing the most fullydeveloped of the crayfish's limbs (Fig. 1), and some others which give a fair notion of the excellence of the illustrations of Prof. Huxley's book.

To this follows a chapter in which the English crayfish is compared in a variety of points with crayfishes of other lands, such as those of Russia (Fig. 2), of Australia (Fig. 3), and of North America (Fig. 4),

FIG. 3.-Australian Crayfish (ra:. size). tinct races characterised by differences of form, the one giving rise to the crayfish of the northern hemisphere (the Potamobiidae), and the other to the crayfishes of the southern hemisphere (the Parastacidae),

The novel portion of this book (novel at least to those who do not study the transactions of learned societies) is that in which Prof. Huxley details the very interesting results which he has obtained by a minute examination of the gills attached to the bases of the legs and sides of the body in all crayfish and allied forms. Three series of these gill-plumes may be distinguished according as they are attached to the leg, to the jointmembrane, or to the side of the body (Fig. 5). An ideally perfect crayfish would have all three series complete on each ring of the body in the branchial region (including the region occupied by the three pairs of maxillipedes and

torrent of heated water. In this case, the fog which is seen to rise from the river is caused by the cold water condensing the vapour of the warmer air above it, which at the time happens to be near the point of saturation. Similarly, the Mississippi, which flows directly from colder into warmer latitudes, is often enveloped in mists or fogs. On the other hand, when the waters of a river are considerably warmer than the air over them, the vapour rising from them is condensed into fog by the colder air through which it ascends; and in such cases the fog will be the denser in proportion to the stillness of the air and its nearness to the point of saturation.

What have been called radiation fogs make their appearance during calm clear nights when the air in contact with the ground gets cooled by radiation, and becoming thereby heavier necessarily flows downwards in much the same way as water, towards the lowest levels, and floods all the low-lying grounds, mingling with and diffusing itself through the moister air of the low grounds, and condensing its more abundant vapour into fog.

Still further in such calm cold weather as has been prevalent for some weeks in the south of England, the temperature of the land falls at a greatly more accelerated rate than that of the sea. When this happens the interchange of light airs and light breezes which set in from the sea landwards and vice versa along a considerable extent of coast, mixes the colder with the warmer and more humid air-currents, and thereby lays a thick covering of fog over the surface.

There is yet another fog of great significance in the study of atmospheric circulation, which spreads over a much wider extent than any of the other fogs referred to. This is the fog which is frequently found in the region of the outskirts of the anticyclone, or rather in the debatable region between the cyclone and the anticyclone. The most probable explanation of it is that it arises from the diffusion of the vapour brought up by the cyclone outwards and through the colder and drier air of those parts of the anticyclone contiguous to it, where it is condensed into immense breadths of fog frequently stretching several hundred miles in length. Much yet remains to be done in instituting, even, an exact and systematic observation of this important weather phenomenon from the results of which we might hope to come at some knowledge of its true meaning and its significance in forecasting weather, particularly those changes of weather which terminate long tracts of fine dry weather.

Now if we examine the weather charts from new year's day to the present time, it is seen that the south-east of England has been constantly either within anticyclones or under their immediate influence, the centres of which kept shifting to and fro over a rudely shaped quadrilateral marked off by Corunna, Sligo, Copenhagen, and Bucharest. During nearly the whole of this time, London has been within the belt of fog and mist which continuously, or discontinuously, has been skirting the margin of these anticyclones. At the same time the air has been unusually calm. Thus at Greenwich for the four weeks ending January 31, the mean daily horizontal movement of the air was only 144 miles, being 182 miles less than the average; and during the five foggy days in the last week of January the daily movement of the air was 269 miles under the average.

Hence, then, the fogs which London has had in common with the south of England and parts of the continent opposite, have been intensified by the low temperatures and still atmosphere bringing from time to time their contributions of radiation fogs and other fogs, still denser, drifting ever and anon through the heart of the city from the adjoining sheets of salt and fresh water. The last touch in the production of the very worst character of these fogs was doubtless given by the smoke of London, in the manner explained by Sir John Herschel in his

"Meteorology," whereby each particle of soot acting as an insulated radiant, collects dew on itself, and sinks rapidly down through the fog as a heavy body, thus giving to these fogs their yellow thick consistency and the suffocating and unwholesome sensation experienced in breathing them.

In the weekly reports of the Registrar.General for December, 1873, several deaths are certified as having been more or less directly caused by the extraordinarily dense fogs which then prevailed; and in one of the reports it is remarked that "In the large provincial towns, where the same cold weather was unaccompanied by fog, the increase in the mortality was slight compared with that which occurred in London." In the last week of January, when the fog was so dense, the deaths in London from whooping-cough rose to 193,-a fatality from this disease hitherto unexampled in the London bills of mortality. A careful examination of the weather and health of London, particularly as regards the deaths resulting from throat and nervous complaints, could not fail to contribute materially to the diffusion of a better knowledge than we yet possess of the influence of these fogs on the public health.

NOTES

DR. BROCA, the eminent anthropologist, has been elected a life member of the French Senate by a majority of eight. This election has created some sensation, Dr. Broca's nomination having been opposed on the ground of his Darwinist opinions. Dr. Broca opened the last meeting of the Anthropclogical Society by a short address, in which he considered his election as a victory gained not only by his political, but also by his scientific opinions.

ALMOST a panic has occurred amongst the wine-growers of Cape Colony, in consequence of the supposition that not only was the Phylloxera causing the destruction of some of the choicest vines, but that it had existed there, undetected, for several years. An influential, and somewhat animated, meeting was held at Cape Town to discuss the subject. We understand that samples of the vines, supposed to have been attacked by the pest, were forwarded to the Colonial Office and sent on to Kew, and that these have been examined by Mr. McLachlan, who is of opinion that all the characteristic signs of the action of Phylloxera are absent, and that nothing is shown to induce uneasiness in the minds of South African wine-growers on this score. The samples had been packed in the worst possible condition for minute examination; but according to a report in a Cape paper, Mr. Roland Trimen, of Cape Town, had examined samples submitted to him on the spot, and pronounced a similar opinion. Some of the vines are undoubtedly in an unhealthy condition, from unexplained causes. It is to be hoped our Cape colonists will not allow panic to take possession of them, and, under its influence, rush into extremes. It is probable that some of the South European nationalities that have carried the absurdity of panic to its highest limit-to the extent of confiscating a bouquet of wild flowers in the hands of unsuspecting ramblers-unwittingly permit the importation of "contraband" vines to a large extent.

Great hope was

ACCORDING to the report of the French Phylloxera Commission, the pernicious insect has spread in a deplorable manner during the last two years, in spite of all measures to the conwhich represent those districts over which the plague has a comtrary. The black patches on the maps of the Commission, and plete hold, must be enlarged year after year. placed in snow, but it proved futile, inasmuch as snow must cover the ground for at least forty-five days to destroy the insects, and nowhere has the snow lasted so long as that. About one-quarter of the French wine-growing districts are now destroyed. All disinfectants prove useless, and it seems hopeless