Of the two phases, diamond and graphite, diamond is the denser, and has also the less internal energy. It follows that, if carbon can be crystallised at comparatively low temperatures, the minimum pressure sufficing to determine the diamond form will be lower than that employed in M. Moissan's experiments.

For estimating the transformation temperature corresponding to low pressures, the data available are incomplete; it is here suggested, however, as a tentative result from experiments which are still in a preliminary stage, that the transformation temperature corresponding atmospheric pressure lies somewhere between 550° C. and 700° C., or not far outside those limits, temperatures having so far been judged only by eye.

to

A molten alloy of lead with about 1 per cent. calcium appears to be capable of holding in solution some small proportion of carbon, which exists either as free carbon

FIG. 1.-Supposed diamond from lead- of the properties of the calcium-carbon solution. diamond. The illustration is from a pencil drawing of a very minute crystal, viewed under a magnification of So diameters, and drawn on a greatly enlarged scale.

The crystals obtained exhibit mostly faces of the octahedron, modified by the cube and dodecahedron; in no case has any internal flaw or lack of perfect transparency been detected in them. The refractive index is clearly very high, and an attempt to determine it by displacement of focus gave 2-43 (instead of 2-47), any convexity of the refracting surface tending to give too low a value. The crystalline faces are, in fact, generally if not always convex, in many cases strongly so. The crystals adhere tenaciously to clean, dry glass; they are unacted upon by ordinary acids (hot or cold), by cold hydrofluoric acid, and by fused alkali at a red heat. When strongly heated on

platinum foil, they burn away, leaving no residue. The quantities at present available are too small for the ready determination of density or hardness.

Negative results were invariably obtained in control experiments on the commercial calcium carbide which was used in preparing the alloys.

Tin may be used in place of lead, but it is freely oxidised by the steam, and the resulting dioxide is troublesome to get rid of. Of other reactions which appear to have yielded minute crystals of diamond, the following may be mentioned-boiling benzene or toluene in contact with finely powdered potassium dichromate or with concentrated aqueous solution of gold chloride; heating benzene or toluene mixed with carbon tetrachloride or chloroform to 200° C. to 300° C. in a bomb. In the last named reactions, nearly all the carbon separates out in the amorphous form, hydrochloric acid collecting under

enormous pressure.

I hope shortly to return to the subject of these experiments, and to make a fitting acknowledgment of my deep indebtedness to Mr. W. J. Hartley, to Messrs. Neville and Heycock, and to other friends. C. V. BURTON.

4 Chesterton Hall Crescent, Cambridge, August 19.

The Spread of Injurious Insects.

IN 1898 Dr. L. O. Howard forwarded to me a scale insect discovered by Prof. Chaves at Ponta Delgada, Azores, attacking the foliage of the orange tree. The insect proved to be new, and was described as Lecanium perlatum. Since that time it has never been reported from any other place; but now I have received some large, flat, dark brown scales on orange leaves from Villa Encarnacion, Paraguay, collected by Mr. Schrottky, and they are this very same L. perlatum.' This is only one new case to be added to the many already known of scale insects being transported from one side of the world to the other, evidently by human means. It is to be regretted that the British Government, with its numerous tropical colonies and excellent botanical gardens, has not done something to make known the scale insects within its domains. It is true that Mr. E. E. Green, the Government entomologist of Ceylon, is bringing out a magnificent work on the scale insects of that island; but he finds insufficient support, and it is divulging no secret to say that the publication of this useful book will involve him in very serious financial loss. There is no properly classified national collection of scale insects (the only good collection in England is that of Mr. Newstead at Liverpool), and we are still totally ignorant of the coccid fauna of many colonies. The reasons for regretting this condition of affairs are mainly two:-(1) because in ignorance pests of this group are continually being carried to new regions, where they are liable to become destructive; and (2) because man is so mixing up the distribution of these insects that every year makes it more difficult to ascertain their natural habitats. Having regard for the experiences of the past, it is surely safe to say that the annual expenditure of a few hundred pounds in the investigation of these pests would be far more than repaid in economic as well as scientific gains. T. D. A. COCKERELL. University of Colorado, U.S.A., August 10.

A Parasite of the House-fly.

parasite of the house-fly which is in this district extremely I SHOULD like to direct attention to an interesting abundant this summer. The creature is, as a rule, very hard to find, and many thousands of flies may be caught in ordinary seasons without a single parasite being found upon them. The animal in question is one of the PseudoScorpionides (? Chelifer), easily recognisable by its pair of long chela, and I should be glad if any of your readers would inform me to what genus it belongs and whether it is equally abundant this year in other places. Eton, August 19.

M. D. HILL.

1 In my original description, it is stated that the skin is not reticulated. The new material shows that it is minutely reticulated or tessellate in the middle of the back. The antennæ, described as 8-jointed, vary to 7-jointed, with the fourth joint longest, but the third nearly as long.

MORE LIGHT ON ANCIENT BRITAIN.1

IT is gratifying, and at the same time puzzling, to find that the antiquities discovered in part of a single county can provide material for two such voluminous works as Canon Greenwell's "British Barrows" of 1877 and the record of Mr. Mortimer's researches, now issued with the assistance of Mr. Sheppard, the energetic curator of the Hull Municipal Museum. The district investigated lies between York and Bridlington, and teems with relics of the past, most of the barrows, or burial mounds, dating from the Bronze Age, but two or three cemeteries containing Anglo-Saxon graves at least a thousand years later. The excavations in which the author has been concerned for so many years are well described; but those without special knowledge of the period will turn with most satisfaction to the introduction, where, with the aid of copious extracts from the earlier work already mentioned, some interesting generalisations are made from the data furnished by the spade. Evidence is brought forward in favour of cannibalism among the ancient Britons, a practice that has been suspected for some time; and human sacrifice, perhaps also suttee, seems to have been indulged in at the burial of an important personage. In some barrows there were signs that a circular hut or a pit-dwelling had been used as a sepulchre, the walls and roof being thrown down over the body; and the author's suggestion as to the

It is interesting to have existing evidence as to the sepulchral pottery confirmed by further discoveries. With a few very doubtful exceptions the so-called "drinking-cup " is never found with calcined human bones, and generally accompanies the primary, or at least one of the earliest burials, in the mound or the grave beneath it. Of the "foodvessels, 43 were found with cremations and 119 with unburnt skeletons; and these figures agree with Canon Greenwell's, giving a proportion of about one to three. Though occasionally found on the top of calcined bones, the cinerary urns, as their name implies, were generally used to contain the ashes of the dead, and "incense-cups" are invariably associated with the rite of cremation, though we must contest the statement that the latter vessels are also

1 "Forty Years' Researches in British and Saxon Burial Mounds of East Yorkshire." By J. R. Mortimer. Illustrated by Agnes Mortimer. Pp. Ixxxvi+452. (Hull: A. Brown and Sons, Ltd., 1905.)

found in Scandinavia, Germany, France, and even the Troad.

The intricacies of the text are considerably simplified by numerous diagrams, giving the plan and vertical section of the barrow under examination, and a specimen is here reproduced to show how it is possible to read the history of a burial mound. One in the Aldro group measuring 84 feet in diameter and 5 feet in height was excavated in 1866. The clay and soil forming the upper part is marked A. while B is a boat-shaped mass of clay and soil below it, c being the chalk filling of the inner mound and grave below the original surface-level Ew. Nos. 1-8 are interments of children and adults in a pit cut rather deeper than usual in the chalk rock; but they were not all complete skeletons, No. 7, for instance, being a "drinkheap containing a ing-cup" in 48 pieces, fragments of six human lowerjaws, and a number of small bones packed in an adult calvarium. Whether contemporary or not, these burials had been surmounted by a dome of chalk which was cut into for another burial at some later date and subsequently covered with the outer mound.

Of the succeeding Early Age of iron remains are few in this particular district, though abundant a few miles further north; but one burial of importance must be noted. The swords here illustrated were found with a skeleton, and belong to two distinct types; the longer is of usual dimensions and has the characteristic curved scabbard-mouth and the chape of the middle period of La Tène, while the shorter sword is the only one of the kind known to have been found in this country, and with similar examples from France and Switzerland may date from about 100 B.C. The human head between the branches of the pommel is evolved from the knob that appears in that position on certain short swords from the Hallstatt cemetery. The Anglo-Saxon

ceme

FIG. 2.-Early British Swords, &c., North Grimston, E.R. Yorks.

teries contain unburnt bodies of which the orientation is instructive, while many excellent brooches and other relics have been recovered. These and the vast Bronze Age series have been amply and creditably illustrated, but, ungallant as it may appear, a protest must be lodged against the frontispiece, which gives a totally false impression of the Grimthorpe sword. In a work containing so many references misprints are excusable, but some are irritating; thus, Inverary (p. 361)

should be Inverury, and the next page has a cruel mutilation of Le Gros Guignon, while the reference to Archaeological Journal on the page before should be to the York volume (1848).

Following an excellent example, Mr. Mortimer furnishes relic-tables with all necessary details at the end of the volume, together with a copious index. Comparison with Canon Greenwell's table shows a very large proportion of primary interments, there being in one case as many as seventeen, to three secondary; but in a matter of this kind different conclusions might be drawn from the same data. Altogether the work is most welcome as a fund of material for more general treatment, and should encourage the study and publication of prehistoric finds in England.

THE FORTHCOMING TOTAL SOLAR

ECLIPSE.

Β' Y the time that NATURE appears next week, the total solar eclipse of August 30 will have become an event of the past, and we hope then to be in a position to announce that the careful preparations, which have occupied the minds of astronomers for so many months past, have been crowned with success.

Since the appearance of Dr. Lockyer's article concerning the eclipse, in our issue of February 23, several important modifications in the proposed arrangements have been made, but most of the eclipse observers are now at their stations erecting or adjusting their instruments for the final scene on Wednesday next. How much depends on the nicety of these adjustments can only be understood by those intimately concerned; but when it is recalled that since the general introduction of photographic methods into eclipse work the sun has only been eclipsed for about half an hour, that the duration of totality in the coming event exceeds 31 minutes, and that no favourable opportunity will occur again until 1912, when totality will only last for about 60 seconds, some idea may be obtained of the anxiety of those observers who are fortunate enough to take an active part in next Wednesday's observations.

Subjoined to this article is a letter from Dr. W. J. S. Lockyer describing the preliminary operations of the eclipse expedition of the Solar Physics Observatory, under the personal direction of Sir Norman Lockyer, K.C.B. When all arrangements for this expedition were nearly completed, but before Sir Norman Lockyer left England, it was decided by the French Government, in quite a friendly spirit, that the presence of a foreign man-of-war in Philippeville harbour was not desirable at the present time; therefore arrangements were made with the Spanish authorities, who rendered such valuable help to the similar expedition in 1900, for the party to go to Palma. Some of the work contemplated at Palma is described by Dr. Lockyer in his letter.

Some novel observations will be made by other observers. In a recent communication to the British Astronomical Association Mr. C. E. Stromeyer pointed out that geodesy might be assisted by an accurate determination of the path of totality. This path has been computed on the assumption that the earth has a certain form, and if the computed values are found to be incorrect, the errors in the assumption might be discovered. Another valuable suggestion was made in a letter from Dr. Johnstone Stoney which appeared in these columns on July 13, wherein the writer pointed out that the planet Mercury will be very near to a line joining the earth and the sun, and will therefore present a very thin crescent to the observer's view.

If Mercury has an atmosphere, the horns of the crescent should appear prolonged by atmospheric refraction, and a careful observer, suitably equipped, should be able to detect the prolongation, and possibly to observe the spectrum of the tips.

M. Touchet suggests that the moon might be observed, both before the first and after the fourth contacts, projected on the brighter portions of the lower corona, by an observer employing a suitable dark glass with a small telescope.

ence

In a brochure recently received from Señor Horacio Bentabol, of Madrid, the author makes a number of suggestions to eclipse observers by which the existof a lunar atmosphere might be detected. Among other matters he suggests that delicate thermometric observations made for some hours before and after the eclipse might exhibit a heat-absorption effect due to the interposition of the lunar atmosphere, between the sun and the observer, before the actual body of the moon was interposed. Solar radiation observations might also exhibit the same effect. Photometric observations of the illumination of the sky might show an analogous absorption of light, due to the lunar atmosphere. Exact determinations of the solar diameter would, if the moon possesses an atmosphere, probably show the results of the refraction due to that atmosphere. The apparent hourly movement of the sun should become modified, as the lunar atmosphere is interposed, for the same reason. Many other points whereby the existence of such an atmosphere might be tested are given by Señor Bentabol.

As recently mentioned in these columns, French astronomy will be well represented at the various stations, whilst American astronomers have journeyed to a number of widely separated stations. Three expeditions have been sent from the Lick Observatory to Labrador, Spain, and Egypt respectively. At each station a search is to be made for an intraMercurial planet, and large-scale coronagraphs of exactly similar construction are to be employed. Should any actual movements take place in the corona during the two and a half hours which elapse between totality at Labrador and at Assouan, the photographs obtained at these respective stations should show it.

The Canadian Government has dispatched an expedition to Labrador, and has officially invited Mr. and Mrs. E. W. Maunder to accompany the same. Mrs. Maunder will employ a coronagraph exactly similar to that which Prof. Turner is using in Egypt.

The details concerning the regions crossed by the eclipse track, and the times of totality, &c., have already been given in many places, but the subjoined table giving the times and magnitude of the greatest phase in these islands may be of interest :Greatest eclipse d. h. m. 30 I 4 30 0 55 30 0 53

Eclips begins d. h. m. Greenwich 29 23 49 Edinburgh 29 23 44 Dublin 29 23 39

Eclipse erds d. h. m. 30 2 15

30 2 4
30 2 5

Mag.

0.786

...

O'724

O'799

and Colonies 23, Italy 11, America 3, and other countries 16. The largest contributors to the proceedings of the congress, however, were the Germans; out of a total of 117 communications, 32 were made by them, 31 by the French, 18 by the British, 15 by the Swiss, 8 by Italians, 5 by Swedes, and 2 by Americans.

From every point of view the congress was a suc

cess.

a

Anatomy is peculiarly susceptible of international treatment, the subjects for description and discussion being concrete and capable of direct demonstration. The language difficulty certainly hindered a free discussion on more than one occasion; for instance, on the second day, a speaker, after after giving his communication in French, listened most attentively to a vigorous criticism in German, and, bowing profoundly, replied, “Je ne comprends pas l'allemand." With an agenda list overloaded with 117 communications, there was grave risk of disorganisation. Thanks to the complete arrangements made by the committee of organisation, presided over by Prof. A. Eternod, of Geneva, and to the perfect arrangement of business by the president of the secrétariat, Prof. von Bardeleben, the proceedings of the congress made an even and steady progress. The success of the congress must also be ascribed to Prof. Nicholas, of Nancy, secretary of the French society; English members were indebted to Prof. Symington, president of the British society, and to Dr. Christopher Addison, its secretary. Each day's work was divided into two parts; the morning was devoted to papers, ten minutes being allowed for each communication, and three minutes to any member who wished to criticise; the afternoon was set aside for exhibition of new specimens and demonstrations of the material on which the communications of the morning were based, and this was by far the most instructive and profitable part of the day's work. The Swiss cow-bell, employed by the president of each day's proceedings (for the president of each society acted in turn as chairman) to warn the speaker that he had reached the limit of his allotted time, bound the members of the congress by a sense of humour and materially aided the success of the meeting. In spite of the entente cordiale, the British anatomists associated more closely with the German than with the French members of the congress-an association determined, for the greater part, by the fact that the Germans were the superior linguists.

common

With so extensive a programme, it is impossible in a report such as this to do more than note the more outstanding communications. Making every allowance for prejudice of race, the first place, both in importance of results and excellence of technique, must be assigned to the contributions made by Prof. J. T. Wilson, of Sydney University, who placed before the congress the results of a prolonged investigation into the developmental history of ornithorhynchus

made by his colleague and collaborator, J. P. Hill, and by himself. With the material now at their command they will be able to write a full and precise account of the development of the monotremes and throw a great deal of light on mammalian morphology. The photograph of an ornithorhynchus egg, in the eight blastomere stage, was shown. Most remarkable of all were the specimens and photographs showing the early developmental phases of the central nervous system. The medullary plates, instead of folding over at an early date to form the neural tube as in mammals generally, remain exposed on the surface of the embryo and thus give a superb opportunity of studying the processes of segmentation and differentiation

of the central nervous system. The cephalic part of the central nervous system is seen at first not to be differentiated into three parts, viz., hind-, mid-, and fore-brain, but into two, a hind part, or archencephalon, and a fore part, or deuterencephalon, under which the notochord terminates. The archencephalon shows four or five sharply demarcated neuromeres in front of the neuromere connected with the facial nerve (prefacial neuromeres), but Prof. Wilson detects in some of them traces of a subdivision. There are three post-facial neuromeres. By using embryos of Perameles and Dasyurus to supply blanks in the ornithorhynchus series, Wilson and Hill were able to show that the neural crest forms at first a continuous hem on the lateral margins of the medullary plates. That part of the neural crest corresponding to the prefacial neuromeres undergoes, relatively to the rest of the neural system, an enormous growth forming a plate of cells which was mistaken by Selenka in other marsupial embryos for a mass of mesoblast. The neural crest connected with the facial segment forms the acoustic ganglion; that with the post-facial neuromeres the glosso-vagal ganglion, the rest of the crest becoming differentiated into spinal ganglia.

It is within the memory of even the younger zoologists that ornithorhynchus was regarded at one time as a toothless mammal; then came the discovery by Poulton and by Stewart that teeth were present but remained embedded in the gums. Prof. Wilson was able to demonstrate in his series of embryos the presence of two dentitions the development and absorption of a milk dentition and the formation of a permanent dentition--that discovered by Poulton and Stewart. Thus ornithorhynchus, so far as its dentition is concerned, takes its place with diphyodont mammals. Further, it was shown that each cusp of the permanent molars is preceded by a separate milk tooth-a powerful argument in favour of the evolution of molar teeth by the concrescence of single-cusped teeth. Photographs were exhibited of a reconstructed model of the skull of a foetal ornithorhynchus which shows many aberrant and puzzling features. Other contributions to the embryology of monotremes were made by Prof. Keibel, of Freiburg (models showing the development of the urogenital apparatus of echidna), and

to

the embryology of marsupials by Dr. Für Bresslau, of Strassburg (preparations showing the development of the pouch of Didelphys marsupialis). Two papers on the agenda list, one by Prof. von Bardeleben, of Jena, entitled, "Die Homologie des Unterkiefers in der Wirbeltierreihe," the other by Prof. Gaupp, of Freiburg, "Die Nicht-Homologie des Unterkiefers in der Wirbeltierreihe," brought again into prominence that much-debated problemthe origin and nature of the mammalian lower jaw. Bardeleben maintained that the lower jaw of a mammal was strictly the same structure as that of a reptile, and produced, as evidence of his contention, mandibles of marsupials and of human foetuses in which there could be traced lines somewhat similar to the sutural lines to be seen in the reptilian mandible. Prof. Gaupp's paper was a clear and vigorous denial of Bardeleben's contentions. Gaupp's opinion the temporo-maxillary joint of mammals was a new joint formed between the coronoid process of the reptilian jaw and the squamosal, and quite different from the mandibuloquadrate joint of reptiles. His conclusions were largely based on a consideration of the relationship of muscles and nerves to these joints. The new mammalian joint was formed in the insertion of the pterygoideus externus, the end tendon of which be

In