admitted that this conclusion needs confirmation from future discoveries before it can be definitely accepted. The specimens on which the new genera Coryphænopsis and Bayeria (Fritsch) are founded are certainly remarkable.

Dr. Fritsch's section of the work shows that all the usual groups of Cretaceous Reptilia are represented in the Bohemian rocks. There are undoubted fragments of Plesiosaurs, and there is one interesting brain-cast which the author describes as probably referable to Polyptychodon. Dr. Fritsch, however, overlooks the fact that the skull of Polyptychodon is actually known in England, and is undoubtedly Plesiosaurian or Pliosaurian, not Mosasaurian. Chelonian remains occur, evidently representing

turtles related to the small Chelone Benstedi from the

English Chalk. Some fragments appear to be Mosasaurian, but those described under the new name of Iserosaurus litoralis are extremely problematical. Other fragments, ascribed without much reason to Dinosauria, scarcely suffice to justify the new names bestowed on them. Some good new figures of the interesting wing-bones of the small Pterodactyl, Ornithocheirus hlavaci, are given, and the volume concludes with a systematic list of species.

A. S. W.

Die Bedeutung des Experimentes für den Unterricht in der Chemie. By Dr. Max Wehner. Pp. 62. (Leipzig and Berlin: B. G. Teubner, 1905.) Price 1.40 marks.

THIS brochure forms part of a "Sammlung naturwissenschaftlich-pädogogischer Abhandlungen," and is very hard reading for an ordinary English chemist. It is divided into two parts, the first of which deals with the importance of experiment for attaining the object of chemical instruction, and the second with the importance of experiment in relation to method in chemical instruction. It is hard reading in the sense that one has to wade through detailed arguments which culminate in conclusions such as "description does not suffice for the instruction of the pupil in chemical processes," and "the development of the laws concerning chemical processes from experimental observations is more effective for chemical teaching than their deduction from quoted examples." The work is, in fact, an example of pure pedagogical exercitation, and it may be recommended with confidence only to those who have a liking for that kind of literature. A. S.

Monographie des Cynipides d'Europe et d'Algérie. By l'Abbé J. J. Kieffer. Tome second. 2me. fascicule. Pp. 289-748; plates ix-xxi. (Paris: A. Hermann.) Price 18s.

THIS is the conclusion of vol. vii. bis of André's great series of monographs, "Spécies des Hymenoptères, and completes the Cynipides, or gall flies. The previous portions have already been noticed in NATURE (vol. lxvii. pp. 124-5, December 11, 1902, and vol Ixviii. p. 221, July 9, 1903), and the part now published completes the Cynipides, 5e tribu, Figitinæ; and also includes the Evaniides (divided into two tribes, Evaniinæ and Gasteruptionina), the the Stephanides, Trigonalides, Agriotypides, general supplements, a "Catalogue méthodique et synonymique,' extending from pp. 653 to 741 (double columns), and general indices.

The plan of the work is uniform throughout, and as the previous portions have already been discussed at considerable length, an extended notice is here W. F. K.

unnecessary.

Richards. Pp. 119. (London: Iliffe and Sons, Ltd., n.d.) Price 2s. 6d. net. THIS process of photographic printing is about fifty years old, but it is only during the last ten years or so that it has been adopted for practical purposes. When first introduced it was deliberately rejected, because it was not equal to the then known processes in reproducing the detail of the negative; latterly it has been taken up and very much appreciated by some of those who desire to be able to alter or "control" their photographic printing, and so obtain results that, while they can lay no claim to mechanical accuracy, more nearly please the aesthetic taste of the worker. At the present time there are more methods of photographic printing than there were a generation ago that are excellently adapted for the purposes of photography pure and simple; therefore the gum-bichromate process is still more than it was then a process for the specialist in the direction named. The author of this volume is well known as a successful worker of the method. He gives his own formulæ, and states clearly the practical details that he prefers to follow, but he also describes the methods of others. He is a warm advocate of "multiple printing"; that is, after coating the paper, exposing, developing with warm water aided with a brush or by other mechanical means, coating, exposing, and developing a second or even a third or more times, so gradually building up the picture with the maximum opportunity of "control. It will be obvious that every possibility of improvement in the hands of the skilful is a probability of error in the hands of the artistically ignorant, and that the process does not claim attention from a photographic point of view at all, but as enabling an artist to express his ideas with less trouble and perhaps with more accurate drawing than if he worked wholly by hand. The volume includes several reproductions of the author's works, some of them showing the print in its various stages of evolution.

LETTERS TO THE EDITOR.

The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts intended for this or any other part of NATURE. No notice is taken of anonymous communications.]

Recent Changes in Vesuvius.

I BEG to enclose a somewhat free translation of a letter I have recently received from Prof. G. Mercalli, of Naples, concerning certain changes which have taken place in Vesuvius this year. During a visit to the mountain on August 14-16, I was able to approach quite near to the sources of the lava streams described by him, and also to examine the remarkable tunnels formed at certain places by the cooled surface of lava streams which had subsequently diminished in volume, or had even "run dry.'

During the week preceding my visit, many incandescent bombs of pasty rock had been ejected from the crater at the summit, mostly in the direction of the side facing Pompeii, and these successively rolling down the ash-slope presented a beautiful spectacle at times. The lava streams proper often presented that curious double appearance, due to the fact that the colder and darker scoriæ, floating down the stream, keep to the more swiftly-moving current in mid-stream, and avoid the sides.

Yesternight (August 20) but one of the lava streams referred to by Prof. Mercalli was visible from Naples, the other having apparently ceased.

The explosions of Stromboli are occurring at intervals of about 3 minutes. R. T. GÜNTHER. R.M.S. Oroya, off Stromboli, August 21.

Lava Stream of May 27, 1905.

In the months of April and May of this year Vesuvius began to show an increased activity, and in the crater, which was about 80 metres in depth, a small cone began to form; it increased rapidly, and by the middle of May had risen to a height of about 15 metres above the level of the enclosing crater.

From May 25 to May 27 violent explosions occurred, which were heard in all the villages on the mountain-side,

FIG. 1.-Source of lava stream of August 26, 1003. From a photograph by Prof. G. Mercal i, taken April 15, 1994.

and were accompanied by the ejection of much red-hot and liquid matter. These explosions ceased almost suddenly on the evening of May 27, and at about 6.45. a small lateral outlet, A," burst through the north-west flank of the great cone at a height of about 1245 metres, and at the point where a seam in the mountain-side showed where the traces of the last eruption of August 26, 1903, still lingered.

A few hours after the first, a second outlet was formed, then a third, "B," both lower down, at an altitude of

FIG. 2.-Vesuvius as seen rom the Observatory Ridge, May 29, 1905. From a photograph by Prof. G. Mercalli.

lava piled itself up in the space between the cone and the hill formed by the lava-flow of 1895; a stream branched off, first toward Mount Somma, but afterwards in a southsouth-west direction, and a small stream more fluid than the main body ran to within a short distance of the electric railway which plies between the observatory and the lower funicular station. Near the fumarole "B" a small heap of scoriæ (a driblet-cone), about 4-5 metres in height, has sprung up; but apart from the explosions attendant on its formation, and which only lasted a few days, there has been no disturbance in the regular flow of the great

streams.

as

The line of white steam seen in Fig. 2 shows the position of the outlets and the course of the lava streams seen from the observatory ridge; the black smoke issuing from the crater indicates the cloud of nonincandescent dust which was cast up after the partial falling in of the walls of the smaller cone on the summit.

We may perhaps attribute the frequency in these latter years of the lava streams from lateral outlets to the increased height of Vesuvius (now about 1330 metres), for the column of fluid lava, when inside the cone, is forced up to a higher level and exerts greater hydrostatic pressure on the sides of it, which are, moreover, much seamed. Formerly, when the mountain was lower, as, for instance, between the years 1840 and 1850, the lava streams generally flowed from the top.

The Millport Marine Station

SINCE the efficiency of such an institution as a biological station is so largely dependent upon the completeness of its library, I do not think any apology need be offered for appealing to those readers of NATURE who are interested in marine biology for assistance in an endeavour to bring together for the use of those working at the Millport Marine Station as complete a collection as may be possible of works having any bearing on the fauna and flora of the European seas. The station already possesses a considerable proportion of the more important monographs, as well as a number of useful pamphlets; but there are still lacking many reference works of importance, and I sure that copies of some of these will exist among the duplicates in many a naturalist's library. I would also urge the claims of the Millport Station upon the generosity of authors for separate copies of any papers they may publish; and in this connection it should be noted that the council of the association has recently agreed that all material intended for private research shall be supplied absolutely free of charge.

am

This occasion may also be utilised to point out some of the advantages which the Millport Marine Station offers to the research student. The fauna of the Clyde area is an extremely rich one, and the water in the vicinity of the station is of most remarkable purity, so that even quite delicate species can be readily kept alive in the tanks. A small steamer, the Mermaid, specially built for scientific research, is constantly at work during the summer months, and brings in daily an abundant supply of material. The tank-room, only part of which is open to the public, has recently been greatly extended, and now has facilities which are probably unsurpassed anywhere for the accommodation of invertebrates and the smaller vertebrates; the tanks are mostly of glazed fire-clay, and capitally adapted for observation and experiment. Besides a well-equipped private research room, there are seven screened compartments in the general laboratory affording ample accommedation for nine students, while a large class-room recently added has benches for forty-five students.

The station is lavishly equipped with apparatus of all kinds-for instance, the student will find here every facility for advanced physiological work. In fine, I think it mas

For some weeks lava issued from these outlets and flowed down the mountain-side in two parallel streams, which from Naples had the appearance of two lines of fire running down the slope of the great cone; towards June 25 the current from "A" ceased, but the stream from "B" continued, and flows more actively than before. On reaching the base of the great cone (Soo metres), the

46

the student find facilities for research on marine biology such as exist at Millport; and, indeed, I know of no marine station elsewhere which can, all things considered offer greater advantages to the biologist. Lastly, it may be mentioned that although the fees are very low, there is never any difficulty in arranging for a free table. S. PACE (Director).

Millport Marine Station, N.B.

up with so much care since August 11. keenness has been displayed in every for its particular duty, and I think that be glad when the eventful day arrives. We have settled down to routine work every day. Those in charge of instruments go to the camp at about 6.15, and work at the adjustments and small items SO necessary for successful photographs. At nine o'clock the whole band of volunteers, now about 150 in number, arrives at the camp, and three drills are then gone through in fairly quick succession. The organisation of the division of labour at each instrument is now very satisfactory, and the various movements that have to be performed at stated times Occur fashion.

The greatest party told off everyone will

Undoubtedly the three minutes three seconds, the length of totality at this station, is a long time, and when the strong voices of the timekeepers are heard shouting out seconds," "153 seconds more, &c., one somehow feels that one is not utilising to the fullest extent the time available.

66

With the prismatic camera, of which I am in charge, it is hoped to secure fourteen photographs. The three large 6-inch prisms of 60°, and the object-glass of the same diameter, form together a powerful weapon of research. The programme of work is to make

in

As I have mentioned before, the whole work of the camp is organised according to signals given by the

FIG. 3.-The north end of the 76 ft. prismatic reflector, showing the dark room with the wine-tub for water, the two handcarts lcaned us, and on the right, under the small awning, the 3-prism 6-inch prismatic

camera.

eclipse clock. There are, however, two further signals given from the angles subtended by the cusp at the centre of the dark room. These angles, which

four snap-shots at about the commencement of totality and five about the end. The remaining five plates will be exposed for intervals varying from 5 to 90 seconds, and it is hoped that the two long exposures on each side of mid-totality will add to our knowledge of the wave-lengths of the coronal rings. This prismatic camera is designed to give results suitable for determining accurate wave-length of the chromospheric and corona arcs; the image of the sun is therefore small, and the dispersion large.

The prismatic reflector of 76 feet focal length, in charge of Mr. Butler, provides a solar image of about 8 inches diameter, and, since the light is made to pass through one prism twice, the dispersion is not excessive. The large chromospheric arcs should, however, provide us with much matter for thought.

This latter instrument is practically ready for the eclipse, and a few words may here be said as regards the erection of it. The camera end itself forms part of the dark room of the camp, and is to the south of it. Just outside, but a little to the west of the north and south line, is the siderostat, which throws the solar rays on to the long-focus mirror situated to the south about 70 feet. This concave reflector throws the image towards the north, into the portion of the dark room in which is fitted a screen. An arrangement is adopted for inserting, during some periods of totality, a prism in front of the mirror. The light from the siderostat has thus to pass twice through the prism, giving a very useful

spectrum. The large size of the image involves the use of very great photographic plates, and in this case plates 2 feet square and 2 feet by 1 foot will be used.

In order to keep out the light from the cloth tube connecting the mirror with the camera, sails have been erected on large spars, making the whole tube a very imposing structure.

Two new additions to eclipse drill have been introduced to render the organisation more perfect and flexible in exceptional circumstances, and both of these have been proved to be necessary. During one

FIG. 4.-The timekeepers at work with the eclipse clock, and their audience.

of the rehearsals the other day the eclipse clock stopped owing to the hand coming in contact with the dial over which it moves. Such an occurrence has never been known in our eclipse history before, and the timekeepers remained dumb after counting "163 seconds more." In future, a man with a stopwatch will stand with the timekeepers and keep a tally of the 10 seconds as they pass.

The second innovation was prompted by the possible absence on the day of the eclipse of any one member of a group working an instrument. Unfortunately, I

FIG. 5.-The colostat end of the 16 ft. coronagraph, which is under the tent on the right.

had to spend the whole of Saturday, August 26, in bed by the doctor's orders; but my instrument was very efficiently worked by the navigating officer, Lieut. Horne, who will make the cusp observations from my siderostat during the eclipse. In each party, then, the work of each member was changed, and drills were carried out under this scheme with success. I should like to take this opportunity of thanking

most heartily both Staff-Surgeon Clift and Surgeon Jones, of H.M.S. Venus, for their very kind and efficient assistance on that occasion.

The camp at the present time practically fills the whole of the enclosed ground placed very generously at our service. Through the kindness of the local authorities, extra tents have been provided, and much material loaned in the way of wood for the shadowband party, handcarts for the use of the men bringing water and provisions from the ship, &c.

To avoid the inconvenience of any dust arising from the road to the north of the camp, the same authorities will keep this well watered on the day of the eclipse, and for some days previous to it, and they have also arranged that the manufacturers' chimneys, which are very numerous here, shall not smoke during the time of the eclipse.

WILLIAM J. S. LOCKYER.

(2) REPORTS OF OBSERVATIONS.

Up to the time of writing very few details as to the actual scientific results obtained during the total eclipse of the sun on August 30 have arrived in this country; but it is very clear that the hopes expressed in these pages on August 24 have not been completely realised on account of the prevalence of cloud during totality at several stations.

Telegraphing from Castellon, Prof. Callendar states that, although the first and last contacts were observed in a clear sky, totality was entirely obscured by clouds. Good records of radiation and temperature were, however, secured. Similarly, Mr. Evershed, who had set up a very fine prismatic camera near to Burgos, says in a telegram to the Royal Society, "Thick clouds; no results." This forms a striking contrast to the reports of the Press correspondents, which state that all the observations at Burgos itself were successfully carried out during a temporary break in the clouds. A reproduction of a photograph of the corona, taken with a camera of 48 inches focal length by Mr. J. T. Pigg at Burgos, appeared in the Daily News for September 2.

At Palma, Majorca, the expedition from the Solar Physics Observatory, South Kensington, under the direction of Sir Norman Lockyer, and assisted by the officers and crew of H.M.S. Venus, were apparently only a little more successful, for as the crucial moment of totality arrived dense clouds came up and obliterated the sun. At about mid-totality, however, a break in the clouds occurred, and some photographs were secured which, it is hoped, may at least show the form and extent of the corona. Several good drawings of this feature, which was of the "maximum" type seen in 1871 and 1882. were made by the "disc" sketching parties.

At Saragossa, cirrus clouds prevented observations being made.

Encouraging but brief reports have been received from the observers at the North African stations.

Mr. Newall, at Guelma, appears to have been singularly fortunate, for he reports superb weather conditions, observations successfully made," and states that he observed a brilliant corona of the "maximum" type having remarkably long streamers -one of which extended towards Mercury for more than three degrees and unusually dark rays. Splendid prominences were also observed by him.

Sir William Christie's report from Sfax is not quite so sanguine, for he states that the sky was partially cloudy; nevertheless, photographs were secured with all instruments, and the eclipse was satisfactorily observed. A Reuter telegram from this station says that during the period of totality no clouds interfered with the observations.