temperatures up to 550° C., which appeared in the Zeitschrift of the Association of German Engineers last year. The work is based on the experimental determinations of the specific heat of steam made by Knoblauch and Jakob and by Knoblauch and Mollier. From these values the author, by a graphical method which solves the thermodynamic equation connecting the rate of increase with pressure of the specific heat at constant pressure with the rate of increase of the expansion with temperature, determines the specific volume over the range stated in the title of his paper. Up to eleven atmospheres and 190° C. the calculated values agree closely with the observations of Linde, so that it seems probable that they may be trusted over the much wider range covered by the author.

THE second lecture on chemistry in gasworks, arranged by the Institute of Chemistry, was delivered by Mr. W. J. A. Butterfield, on January 31, at University College. Mr. Butterfield showed that the sensitiveness of lead acetate paper as a test for the presence of sulphuretted hydrogen varies inversely with the area of the paper exposed to the gas. The sulphur impurity remaining in gas after the extraction of sulphuretted hydrogen, he considers to be objectionable on account of its destructive action on the metalwork of inverted burners and fittings directly exposed to the undiluted products of combustion of gas. In connection with the by-products of gas manufacture, he stated that the predominant uses of tar at present are for the production of pitch for the supply of the patent-fuel industry of South Wales, and for road construction and treatment. Physical tests of tar and pitch are misleading as to the value of these materials for the latter purpose, because the physical characteristics change with efflux of time, and the extent and bearing of the changes which thus occur in tår and pitch can be ascertained only by appropriate chemical examination of them. Mr. Butterfield directed attention to the acceptance practically everywhere, except in German-speaking countries, of the Harcourt 10-c.p. pentane lamp as the reference standard of light for all photometric work. The secondary electric standard lamps are calibrated by comparison with it Comparative tests have been made of the light afforded by about 150 different specimens of the Harcourt 10-c.p. lamp, and a disagreement by more than 0.2 per cent. has never been found, except in cases where there has been a fault in construction.

AT the sixth congress of the International Association for Testing Materials, held in New York last September, fifteen papers were submitted dealing with impact and endurance tests. These are summarised by Dr. W. Rosenhain in The Engineer for January 31. In drawing conclusions, Dr. Rosenhain states that the general feeling at the congress was not in favour of introducing impact tests into specifications as yet. While enough has been done to show that some form of impact test is desirable, there is a lack of consistent results from different machines and different forms of test pieces. It is evident that what is now required is carefully directed research by many independent workers with the view of clearing up the causes of discrepancies. Further progress in mechanical test

ing by dynamic methods should be sought by simplify. ing the test conditions as much as possible, and by arranging the experiments in such a way as to isolate and measure one single physical property or constant of the material, rather than by any attempt to imitate in the laboratory the complex conditions of practical

use.

A COPY of the Almanac of the Egyptian Government for 1913 has been received. In addition to full particulars of the various Government departments, the Almanac contains valuable meteorological, magnetic, and other scientific data.

A COPY has been received of a new, revised, and enlarged edition of the pamphlet published in 1908 by Ilford, Ltd., giving notes on the Ilford X-ray plates. Scientific workers desiring to possess copies of the pamphlet, which is effectively illustrated, may obtain them, free of charge, on application to the company at Ilford.

OUR ASTRONOMICAL COLUMN. COMET 1912a (GALE).—Gale's comet, discovered in September last, is now a circumpolar object, of about the tenth magnitude, in our latitudes. From the following ephemeris, abstracted from a daily ephemeris published by Dr. Ebell in No. 4627 of the Astronomische Nachrichten, it will be seen that the comet is now travelling southwards through Cassiopeia, and may be observed high up in the west during the evening.

1913 Feb. 7

II

3 15 1

+78 45 +76 24

Feb. 19

4 17'2

+71 56'2

+74 7

23 27

4 29'9 4 40'6

+69 51'7 +67 543

3.42'1 15 4 18 Observed by Herr G. van Biesbroeck at Uccle between January 4 and 9, the magnitude of the whole comet was about 90, and the diameter, observed in a finder, was about 10'. In No. 4625 of the Astronomische Nachrichten, Herr Moschonkin directs attention to the similarity between the elements for Gale's comet and those for a comet which appeared in 1672.

THE EXPECTED RETURN OF FINLAY'S SHORT-PERIOD COMET.--With a period of 6.5 years, the comet discovered by Finlay at the Cape in 1886 is shortly due at perihelion. According to elements previously calculated by M. Schulof, perihelion passage should take place on March 24, but the comet passed very near to Jupiter in the summer of 1910, and, from a study of the perturbations, M. G. Fayet finds that perihelion has probably been advanced by about six weeks. His new elements, published in No. 4626 of the Astronomische Nachrichten, give February 6 as the date and he gives three search-ephemerides based on the assumptions that perihelion would be passed on February 6, January 29, and February 14 respectively. The first gives the present position as lying in Aquarius very near the western horizon at sunset. At no time during this apparition will the comet be an easy object, chiefly owing to its apparent proximity to the sun, but it may be rediscovered by means of one of the powerful instruments now available; during February the theoretical brightness is about that at the time of the comet's discovery.

THE MAGNITUDE VARIATIONS OF NOVA GEMINORUM No. 2.-A large number of observations, made at

several observatories, of the magnitudes of Nova Geminorum No. 2, are published in No. 4624 of the Astronomische Nachrichten. In addition to the tables giving the magnitudes recorded at the Berlin Observatory, Herr Freundlich publishes a light-curve showing the variations of the nova's magnitude from March 14 to May 18, 1912. This curve agrees fairly well with that previously published by Herr FischerPetersen, and shows maxima, successively decreasing in intensity, on March 14, 23, April 3, 19, and May 1.

POSSIBLE CHANGES OF A LUNAR FEATURE.-In the January number of L'Astronomie, M. Pierre Stoïan directs the attention of lunar observers to a small "hill" which, according to his observations, undergoes changes of form and size. This small feature lies to the north of the line joining Thebit and Birt, and about half-way between the former and the small crater at the northern end of the Straight Wall. M. Stoian points out that Nasmyth recorded nothing in this position, Neison saw a double peak, and the

being a wavy line, each minute being especially marked; the images of the transit-threads are also impressed upon the plate, so that any plate may be measured or re-measured at leisure, the time of starting the exposure having been recorded. The excellence of the images is shown by a plate accompanying the paper, and a comparison of Herr Trümpler's with other results promises well for the photographic recording of star transits.

THE MARINE BIOLOGICAL STATION AT PORT ERIN.

THE HE twenty-sixth annual report of the Liverpool Marine Biology Committee gives evidence of the rapidly increasing importance of the laboratory at Port Erin as a centre for research and for the instruction of students. The number of workers has more than doubled during the last six years; there were seventyfour workers during the year 1912. The extension

Paris photographs show a crescent-shaped eminence which to Gaudibert was an oval; others have recorded it as larger than the smaller of the two small craters in the N.E. wall of Thebit, while to some observers it has appeared to be smaller. The feature appears to be worth further attention on the part of selenographers.

PHOTOGRAPHIC TRANSIT OBSERVATIONS.-By the munificence of Messrs. Krupp, Prof. Ambronn was able to secure a photographic transit apparatus for use at the Göttingen Observatory in the early part of 1911. The instrument has been tested and used by Herr R. Trümpler, who describes it and the results secured in No. 4620 of the Astronomische Nachrichten. The focal length of the Göttingen instrument is 180 cm., the aperture 18 cm., and photographic transits of stars down to the eighth magnitude may be secured. A slight relative displacement every second results in the photographic trace of each star

effected two years ago has been fully occupied, and the director (Prof. Herdman) reports that already further accommodation for research is urgently required.

Among noteworthy matters mentioned in the report are the weekly lessons and demonstrations given by the curator (Mr. H. C. Chadwick) to the boys from the local secondary school.

Prof. B. Moore and his colleagues are carrying out an extensive physiological and chemical investigation into the nutrition and metabolism of marine organisms. The results show that the amount of organic carbon present in the sea-water is almost negligible, being well below one milligramme per litre of water, and that Pütter's estimates are incorrect. They also show that, while the plankton-supply, as found generally distributed, may prove sufficient for the nutrition of such sedentary animals as sponges and ascidians, it is quite inadequate for active animals, such as crustaceans, molluscs, and fishes. These latter, however,

In spring (April) the water, not only near the shore but in the open sea, is acid to phenolphthalein, while in summer (August) it is distinctly alkaline to the same indicator, a change which signifies an enormous conversion of carbon in the inorganic into carbon in the organic form.

Prof. Moore, Dr. Adams, and others have studied the chemical changes taking place in the reproductive organs of the sea-urchin. They have found that, under normal conditions of nutrition, the amount of food consumed by a sea-urchin is many times that required for the ordinary metabolic uses of the animal. The excess is converted into storage products-glycogen, lecithides, and fats-which, throughout the non-breeding period, accumulate in the reproductive organs in quantities as great as are usually found in the liver or hepato-pancreas of other animals, and form a reserve for use during the breeding season.

Prof. Herdman has continued his observations on the occurrence of the dinoflagellate Amphidinium on the beach at Port Erin, and records certain variations in the form of this organism, and the alternate appearance in the same area, during the early part of the year, of Amphidinium and of diatoms (cf. NATURE, November 28, 1912, p. 371).

Prof. Herdman and his assistants have collected and examined, during 1912, about 400 samples of plankton from Port Erin and the neighbourhood. These show that diatoms, dinoflagellates, and copepods succeed each other in the summer plankton of the Irish Sea. The autumnal phyto-plankton increase was greater than usual in 1912, immense numbers of diatoms, chiefly Chatoceras, being present in the latter part of September. Plankton gatherings were also made along the chain of the Outer Hebrides, and proved to be oceanic in character.

NOTES ON THE CEREMONIES OF
THE HOPI.1

MR. H. R. VOTH is known to all students of North American ethnology for his researches into the sociology and religion of various Pueblo groups, and now, owing to the resources of the Stanley McCormick benefaction, they are indebted to him for further studies on the Hopi of Arizona. The description of the Oraibi winter and summer Marau certmonies is the result of several partial observations in different years; as the ceremonies are sometimes going on day and night, it is a physical impossibility for one man to make an exhaustive study of a nine-day (and night) ceremony at one time, but a protracted study of the same ceremony, on different occasions, has several compensations, and it is evident that Mr. Voth has done all that was possible to render his account accurate and as complete as circumstances would permit.

As an instance of Mr. Voth's method, it may be mentioned that he gives the names of those who take important parts in the ceremonies. Even these isolated villages are subject to the social and religious influence of the white man, so these careful investigations are of especial value. In addition, "Strife and contentions between the different factions have driven a large part of the inhabitants from the village [of

During this Hebridean cruise, specimens of the ascidian Syntethys hebridicus were dredged. They were pale green when alive, but when placed in spirit became mauve or violet in colour. The colour is due to a new pigment, syntethine, the absorption-bands of which differ from those of chlorophyll and bonelleine (see Fig. 2).

Oraibi]. These have started new villages. This fact makes it highly probable that the Marau ceremony, as well as the others, will, in the future, never be the elaborate affairs that they used to be in the past."

1 Field Museum of Natural History. Anthropological series, vol. xi., No. 1, Publication No. 156. "The Oraibi Marau Ceremony." By H. R. Voth. Pp. 86+plates. Vol. xi. No. 2, Publication 157. Brief Miscel laneous Hopi Papers." By H. R. Voth. Pp. v +99-149. (Chicago, 1912)

The chief interest of the Marau Society is that it "is a woman's fraternity, and in Oraibi has its own kiva, or underground ceremonial chamber; but, as is the case with all women's societies, a number of men also belong to the order, who perform certain functions and control certain sacred objects in all the ceremonies." The cult conforms to the usual type of the ceremonies

The ceremonies are too elaborate to describe; they consist largely of ceremonial smoking, asperging, sprinkling meal, offering feathered prayer-sticks, repeating prayers, and the like (Fig. 1). It is significant that this woman's ceremony is connected with agriculture, and that, as in other societies, the summer or autumn ceremonies are more

elaborate than the winter performances. A free translation of one of the songs runs as follows:-"Now, then, here we array (decorate), these four different ones (somewhere in the four world quarters), our fathers, the chiefs (deities); therefore cooperate we here with our offerings. From somewhere, may, with their help, the four different ones (the deities of the four world quarters) have pity upon us quickly, and let it rain at the right time."

Mr. Voth has wisely given all the details he observed, but it would be very helpful if he would prepare a short synopsis of this and other ceremonies giving only such details as are sufficient to illustrate the symbolism of the ritual, and describing the real significance of the ceremony and the religious

sentiments which it is de

signed to promote. Certain words in many songs, and often those of entire songs, are not understood by the Hopi; generally these are not archaic Hopi words or songs, but have been introduced from the Pueblo Indians on the Rio Grande another example of cultural borrowing.

In the notes on modern burial customs of the Hopi Mr. Voth says that a child which has not yet been initiated into one of the religious societies is not buried in a cemetery but a crevice in the edge of the mesa (Fig. 2). A road is made then towards the child's home, because it is believed that the soul of that child returns to the house of its parents, and is reincarnated in the next child to be born in that family. Other notes deal with the Eagle cult of the Hopi, the Oraibi new year ceremony, the winter ceremony of the Drab Flute Society, and Hopi marriage rites. An important element in the last is the washing of the hair of the couple, "and especially the washing of the two heads in the same bowl is said to be the 'crucial moment' in which the two are supposed to become one.'" Most of the articles are richly illustrated by photographs.

of the Pueblo Indians. There are altars with a screen of slabs of wood representing cornstalks, lightning, and deceased members of the order, at the sides are figurines of the deities of the order, in front is the medicine bowl with six ears of corn, aspergills, &c., trays with meal, rattles, bone whistles, and other articles used in the rites.

A. C. HADDON.

OF CORAL REEFS.

DWIGHT DANA, born four to a

after Darwin, on February 12, 1813, naturalist of the United States Exploring Expedition under Wilkes from 1838 to 1842, and afterwards until his death in 1895 professor of geology at Yale University, was for more than half a century a leading figure among American men of science. On the hundredth anniversary of his birth it is fitting to direct attention to the independent proof that he found many years ago for Darwin's theory of coral reefs, a proof that has long been overlooked, although it supplies the most important confirmation for the theory of subsidence that has ever been brought forward.

Darwin most ingeniously invented his theory of subsidence while he was in South America, before he had seen a true coral reef; he had afterwards only to test the theory by comparing its consequences with the facts that he observed during the voyage of the Beagle across the Pacific and Indian Oceans, and with the records of other explorers which he studied after his return home. The theory bore the test admirably; it was universally regarded as "true for a generation, although apart from certain correlations of coral reefs with areas of recent uplift and with active and extinct volcanoes, which appear to be less assured now than seventy years ago, the theory of subsidence did not gain that increased probability of correctness which comes to a theory from the capacity to explain facts that were unknown or unnoticed when the theory was invented.

During the last thirty years several new theories of coral reefs have been introduced, and Darwin's theory has been more or less discredited in the minds of some investigators. Murray re-introduced what may be called the theory of outward growth, which Darwin had considered and adopted for certain special cases in association with subsidence; but in its new form subsidence was excluded from this theory, and two provisos were added as to the organic upbuilding of submarine banks until they reach the moderate depth at which they may serve as foundations for atolls, and as to the production of lagoons by the removal of the inner part of reefs by solution (Proc. Roy. Soc., Edin., ix., 1880, 505-518). Agassiz, in his world-wide explorations of coral reefs, emphasised the possible complications in their history; he pointed out the frequent occurrence of uplifted "coralliferous limestones,' ," which might be worn down and dissolved away while fringing reefs grew around them, thus producing barrier reefs and atolls in association with elevation instead of subsidence. At the same time he reintroduced the idea-which Darwin had rejected on good grounds—that reefs could grow on the outer margin of platforms cut by the waves around volcanic islands, thus producing barrier reefs without subsidence, elevation, or solution (Bull. Mus. Comp. Zool., xxxiii., 1899; Mem. Mus. Comp. Zool., xxviii., 1903). Wharton went still farther in suggesting that a volcanic island might be worn down to a depth of twenty or twenty-five fathoms by marine agencies, thereby producing a flat submarine bank on which an atoll could afterwards grow up; thus accounting for atolls as Agassiz had for barrier reefs, without subsidence, elevation, or solution.

The possibility of producing barrier reefs and atolls by the wearing down of uplifted "coralliferous limestones," as suggested by Agassiz, may be regarded as a modification of any theory that will explain barrier reefs and atolls before the uplifts occurred. Darwin recognised at least one instance of wearing down an uplifted reef ("Coral Reefs," 1842, p. 55), and

The formation of atolls by up-growth from submarine banks of proper depth is eminently possible, if the banks can be provided in sufficient number, but possibility is not proof. When subsidence is demonstrated as having taken part in the production of barrier reefs, as will be shown below, its exclusion from this theory of atolls is unreasonable.

The development of a foundation of atolls by the marine truncation of a volcanic island, as indicated by Wharton, is eminently possible, provided that floating coral larvæ do not establish themselves upon it until truncation is complete; but the ordinary rela tion of fringing and barrier reefs to their central islands shows that this proviso is inadmissible. The formation of a fringing reef will be begun as soon as a narrow platform is abraded, and such a reef once established, further truncation of the island by wave work is practically stopped. Moreover, the Alexa and other submarine banks described by Wharton can be explained by regarding them as submerged atolls quite as well as by regarding them as truncated volcanic islands; hence this theory is not satisfactory.

The formation of veneering barrier reefs on the outer margin of sea-cut platforms around still-standing islands, an old idea (see footnote in Darwin's "Coral Reefs," 1842, p. 49) recently given prominence by Agassiz, is open to the same difficulty that is fatal to Wharton's theory of truncation. However, if a barrier reef were ever formed in this manner, the central island should rise from the cut-back shore line in a wall of steep cliffs, as Darwin clearly stated, and the broader the platform, the simpler the outline of the cliff-walled island should become. It may be confidently asserted that the central islands of barrier reefs do not possess these significant features; hence there is no more reason for accepting this theory to-day than when Darwin rejected it.

The theory of outward growth and solution, advo cated by Murray for the production of barrier reefs around volcanic islands, without subsidence, or even in areas of slow elevation, involves several consequences which, when compared with the facts, contradict its verity; for during the slow outward growth of the reef around a still-standing island, the streams from the mountainous interior must form deltas in the shallow water at their mouths, and by the time the reef has grown far enough outwards to be called a barrier, the delta plains must become more or less confluent laterally, thus forming a low alluvial plain around the original island, as Darwin clearly saw ("Coral Reefs," 1842, pp. 128-130). When such lowlands occur, they indicate a still-stand of the island; but their prevailing absence suffices to exclude the general application of the postulated stillstand.

It would thus appear that the theories of outward growth and solution for the production of barrier reefs, of marine truncation for the production of atolls, and of coral veneers on the margin of sea-cut platforms for the origin of barrier reefs, all fail to satisfy the requirements of observation, when they are tested by certain consequences that have not been explicitly stated by their inventors. It remains to be seen whether Darwin's theory of subsidence suffers the same fate when tested in the same manner.

The accompanying diagram (Fig. 1) exhibits three stages in the subsidence of a dissected volcanic island; the first stage shows a fringing reef, the second a barrier reef, the third an atoll, as indicated by Darwin's original figures, which are here reproduced in