tion in each particular case. As employed by Malays, who are followed both by Dutch and English travellers, the word has scarcely better standing-ground in a scientific terminology than has "Álfuro."

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The following fact with regard to the Sea Dyaks may be of interest. When Europeans first entered Sarawak the Kayans, properly so called, were dominant in the great Rejang River, and the Sea-Dyaks were strictly confined to the Batang Lupar, Saribas, and Kalakah rivers. Now the Sea-Dyak population of the Rejang is some 30,000, and the Rejang Dyaks are rapidly occupying the Oyah, Mukah, and Tatau rivers further up coast. On the original Sea-Dyak rivers the people always use the expression 'we Dyaks" when they mention their own race; but on the Rejang the expression "we Iban" will invariably be heard the explanation being that the Kayans habitually desig nate Sea-Dyaks as "Ivan" among themselves, whence the Dyaks have applied the name; but having no v-sound in their language, they say "Iban." The Kayan proper is rich in v-sounds. I have been informed, though I cannot vouch for the accuracy of the statement, that "Ivan" in Kayan is a term carrying with it a sense of opprobrium. However this may be, it is remarkable that so large a section of the Sea-Dyaks, who are so thoroughly dominant in Rejang, and are in constant daily communication with their original seat in the rivers to the westward, should in the course of some thirty years have come to habitually speak of themselves by the name given them by their foes. And it is the more surprising because the Sea-Dyaks generally give new names of their own to the geographical features of the district into which they immigrate. Papar, North Borneo A. HART EVERETT

Seeing by Electricity WE hear that a sealed account of an invention for seeing by telegraphy has been deposited by the inventor of the telephone. Whilst we are still quite in ignorance of the nature of this invention, it may be well to intimate that complete means for seeing by telegraphy have been known for some time by scientific men. The following plan has often been discussed by us with our friends, and, no doubt, has suggested itself to others acquainted with the physical discoveries of the last four years. It has not been carried out because of its elaborate nature, and on account of its expensive character, nor should we recommend its being carried out in this form. But if the new American invention, to which reference has been made, should turn out to be some plan of this kind, then this letter may do good in preventing monopoly in an invention which really is the joint property of Willoughby Smith, Sabine, and other scientific men, rather than of a particular man who has had sufficient money and leisure to carry out the ide1. The plan, which was suggested to us some three years ago more immediately by a picture in Punch, and governed by Willoughby Smith's experiments, was this :-Our transmitter at A consisted of a large surface made up of very small separate squares of selenium. One end of each piece was connected by an insulated wire with the distant place, B, and the other end of each piece connected with the ground, in accordance with the plan commonly employed with telegraph instruments. The object whose image was to be sent by telegraph was illuminated very strongly, and, by means of a lens, a very large image thrown on the surface of the transmitter. Now it is well known that if each little piece of selenium forms part of a circuit in which there is a constant electromotive force, say of a Voltaic battery, the current passing through each piece will depend on its illumination. Hence the strength of electric current in each telegraph line would depend on the illumination of its extremity. Our receiver at the distant place, B, was, in our original plan, a collection of magnetic needles, the position of each of which (as in the ordinary needle telegraph) was controlled by the electric current passing through the particular telegraph wire with which it was connected. Each magnet, by its movement, closed or opened an aperture through which light passed to illuminate the back of a small square of frosted glass. There were, of course, as many of these illuminated squares at B as of selenium squares at A, and it is quite evident that since the illumination of each square depends on the strength of the current in its circuit, and this current depends on the illumination of the selenium at the other end of the wire, the image of a distant object would in this way be transmitted as a mosaic by electricity. A more promising arrangement, suggested by Prof. Kerr's experiments, consisted in having each little square at B made of silvered soft iron, and forming the end of the core round which

the corresponding current passed. The surface formed by these squares at B was to be illuminated by a great beam of light polarised by reflection from glass, and received again by an analyser. It is evident that, since the intensity of the analysed light depends on the rotation of the plane of polarisation by each little square of iron, and since this depends on the strength of the current, and that again on the illumination of the selenium, we have another method of receiving at B the illumination of the little square at A. It is probable that Prof. Graham Bell's description may relate to some plan of a much simpler kind than either of ours; but in any case it is well to show that the discovery of the light effect on selenium carries with it the principle of a plan for seeing by electricity. JOHN PERRY Scientific Club, April 21

W. E. AYRTON

Musical Sounds within the Ear

I SHOULD like to know how far the musical sounds, which we sometimes hear within our ears, are of different pitch in different persons. From repeated observations I find that my left ear gives G, and the right one B. A friend of mine, who is a good performer on the violin, finds F and A respectively.

It is perhaps not without interest that in some parts of Germany (at least in Silesia) people believe these sounds to be indicative of one's being talked about, and that the sound ceases as soon as one thinks of the person who is supposed to do so. Caracas, March 18

Ice Filaments

A. ERNST

"THE Comb-shaped masses of ice of fibrous structure" mentioned by your correspondent, in explanation of the inquiry made by the Duke of Argyll, are observed every winter in the southern portion of the United States, especially on the sloping sides of a path or country road where the surface-earth has been removed, and the natural clay sub-soil is not rendered compact by being trodden. The conditions requisite for its abundant production are a sudden reduction of temperature below the freezing-point when the clay soil is thoroughly saturated with water. When this occurs at sunset, the next morning, if the night continues favourable, will disclose a vast collection of fibrous filaments, from two to six inches in height, rising from the soil in close juxtaposition, generally holding aloft in their caps portions of the soil, the longest crystals appearing when the soil is free from surface-loam.

I have frequently given to my class this explanation of the phenomena.

The capillary tubes of the soil are all filled up to the surface with water. The sudden reduction of temperature freezes the

water at the surface, but does not chill it within the soil below 32° F. The consequence is that this expansion, caused by congelation at the upper extremity of the capillary tube, compresses the walls of the tube externally, and causes the mouth of the tube at the surface to assume a conical shape, as in diagram. The conge lation of all the water within the conical cavity causes pressure normal to the surface of the cone at a and b, and hence produces a vertical resultant, r, that raises the cone of ice. Capillary action imme. diately fills the little cavity with water, which in turn is frozen and elevated by the expansion force of its congelation. The filament thus grows in this simple way from its base. The soil in which the e fibrous crystals or filaments form is never frozen ; thus proving the correctness of the explanation.

They are formed very rapidly. I have on more than one occasion, when a sudden chill at sunset would start them growing, listened to the crackling of the little ice-crystals as they would break loose from each other, being pushed up by this expansive force.

I infer the filaments of ice formed on rotten wood are due to a similar cause, and that they will not be formed unless the reduction of temperature is quite sudden. That is, if the reduction of temperature is so gradual that the water somewhat below the surface in the cylindrical portion of the capillary tube is frozen, the crystals will not be elevated, but the ground will be frozen. WM. LEROY BROUN

Vanderbill University, U.S.

Ophiolepis mirabilis

IN a review of Lyman's description of the Ophiurans of the Challenger, which appeared in NATURE, vol. xxi. p. 513, I was much surprised to find a criticism relating to a remarkable species which I described last year in the Proceedings of the Linnean Society.

The reviewer informs your readers that Ophiolepis mirabilis, Duncan, is a true Ophiopholis, having all the structures of the genus, and that it is allied to O. aculeata. This simple statement leaves the impression that I have made a mistake, and that I am ignorant of a well-known form. I therefore extract the following from the Proc. Linn. Soc., vol. xiv., Zool., p. 479, 1879

66

Ophiolepis mirabilis.-This common species has the disk of Ophiolepis as diagnosed by Müller and Troschel; that is to say, the scales, which are of good size, and the large radial shields are environed by rows of small scales, as by belts. But the upper arm-plates have also the supplementary rows of small scales around them, and there are also large accessory side-pieces. Moreover, there are hooks on the side arm-plates. This mixture of Ophiolepian and Ophiopholian characters is very interesting, and this species, I consider, renders the abolition of Ophiopholis as a genus inevitable." In fact the beautiful Ophiuran is a synthetic type, and I prefer its teachings to authoritative statements. P. MARTIN DUNCAN

Hastings, April 9

The Stone in the Nest of the Swallow

YOUR correspondent, P. P. C. Hoek (Leiden), will find the information which he asks for under this heading (vol. xxi. p. 494) in an article which appeared in the Zoologist for May, 1867, entitled "An Inquiry into the Nature and Properties of the Swallow Stone and Swallow's Herb," by J. E. HARTING 24, Lincoln's Inn Fields, London, W.C., April 14

THE SONGS OF BIRDS.-Mr. C. C. Starling asks to be informed of any book or paper which treats upon the musical properties of the songs of birds.

DEW CLAWS.-A. N. asks if any correspondent familiar with wild species of Canis can tell him whether the rudimentary hind toe is invariably present, or, if not, in what proportion of individuals, and whether it has bony function with the metatar us?

THE EASTER EXCURSION OF THE GEOLOGISTS' ASSOCIATION TO THE HAMPSHIRE COAST1

THE

HE head-quarters of the Association were fixed at Bournemouth. A large number of members arrived before Easter, and were able to explore the freshwater series to the west of Bournemouth, which could not be visited on the excursion. An excavation into the leaf-beds having been opened a few days previously by Mr. Gardner, Prof. Morris, Dr. Henry Woodward, Prof. Corfield, and Mr. Birch, a number of fine leaves were obtained, and Dr. John Evans, Prof. McKenna Hughes, Mr. Warrington Smyth, Prof. Bonney, and many others, were enabled to see the leaves in situ and the method of work.

On Easter Monday some fifty or sixty members assembled, and the party proceeded to Boscombe. On the way the director pointed out the position of the Bournemouth series in the eocene formation, and the chief geological features of the coast. Far to the west could be traced the cliffs whence had been obtained a rich dicotyledonous flora, shed apparently from forest trees, which clothed the hilly slopes of the right bank of the eocene river. It is remarkable to notice in how many respects this flora differs from those found nearer Bournemouth, most notably so in the total absence of palms. The next mass of cliffs is almost unfossiliferous, and from its confused bedding is now conjectured to present a transverse section of the actual bed, silted up, of the old eocene river. Between this and Bournemouth, for nearly a mile, extends the eastern series of leafbeds, containing the remains of a more tropical flora, derived, perhaps, from low-lying country on the left

Director, J. Starkie Gardner, F.G.S. &c.

bank of the old river. Among the palms, which are abundant, can be recognised such genera as Phoenix, Calamus, Iriartæa, Sabal, &c., and among the ferns, species scarcely differing from such magnificently tropi cal forms as Ósmunda javanica, Chrysodium aureum, Gleichenia dichotoma, Lygodium dichotomum, &c. Beyond these cliffs, skirting the downs of nearly vertical chalk, are the Lower Bagshot beds, in which the well-known leafbeds of Creech Barrow, and Alum and Studland Bays are situated. A very small portion, however, of the freshwater Bournemouth series could be actually examined on Monday, for the chief object in view was to investigate the recently-discovered marine series, described for the first time in the pages of the Journal of the Geological Society less than twelve months ago. The passage from the one series to the other was well seen, although from the absence of slips and consequent inaccessibility of the beds, few fossils could be obtained. The beds are mostly dark sandy clays, highly charged with lignitic matter, and they contain in places well-preserved fruits and teredo-bored wood. The evidence of their marine origin is amply demonstrated by the presence of casts of Bracklesham mollusca, masses of oysters, bryozoa, and crustaceans. Overlying them are the clean white sands, with flint shingle beds, of the Boscombe series. These eocene shingle beds, from the perfectly-rounded form of the pebbles composing them, show the former prevalence of heavy surf upon the old shore-line. In many cases the condition of the silex is wholly or partially changed into a soft, white, chalk-like mass, entirely free from carbonates however, and much speculation was indulged in concerning the nature of this change. The party having been joined by Dr. Alman, president of the Linnean Society, and Mr. Pike, owner of the vast china-clay pits near Wareham, the curious Honeycomb chines were explored, and the zone of nipadites pointed out, crowded in places with the empty husks of fruits which hal floated out to sea. At another point proteaceous leaves and tubular borings of annelids, filled in with horizontallydisposed lignitic matter, were noticed. On the way to Hengistbury Head it became apparent that as the freshwater beds present a transverse section across a vast river channel, so the marine beds present a similar section through a great eocene beach which formerly sheltered a stagnant lagoon. These towards the east are seen to be composed of larger and larger shingle, whose well-rolled appearance indicates the distance it must have travelled. Attention was particularly called to the resemblance of the Boscombe series to the so-called Upper Bagshots of

the London Basin.

Arriving at the Headland, after skirting its base and examining its remarkable geology, the party somewhat rapidly made their way through the heather on the summit, past the prehistoric double wall and ditch, ani across the Stour and Avon by ferry to Christchurch, where Mr. George H. Birch gave a most interesting historical sketch of the priory.

The second day was devoted to the cliffs between Mudiford and Hordwell. The main features of the coast were well seen as the haze lifted. The sequence of the beds from Hengistbury to Highcliff was pointed out b the director, and the Barton clays and sands, the Upper Bagshots and Headon beds of Hordwell were examined. and numerous fossils collected. During the short stay for lunch Prof. Morris favoured the party with an address, in which he clearly placed before them the data for the correlation of these beds with those of the rest of Europe, and sketched in eulogistic terms the work of those who have made it possible to trace the history of their deposition The members reached Lymington in time to return to London or Bournemouth by the 5.50 train.

The excursion, which was unusually largely attended, was keenly enjoyed, owing to the magnincent weather and the beauty and interest of the country traversed.

DEEP-SEA DREDGING AND LIFE IN THE DEEP SEA1

III.

HOW is it that the general absence of ancient forms from the deep sea is to be accounted for? It is hardly probable that the struggle for existence in the great depths is very severe. The fact that so helpless an animal as a Pycnogonid can grow to a length of two feet points to the existence of easy conditions of life. Even if the struggle in the deep sea were as great as in shallow water we might have expected that it would extinguish these different forms from those which it exterminated near the shores. It seems on the whole probable that the deep sea may have been entirely devoid of life during the earlier geological epochs. The modifications existing in deep-sea animals as adaptations to their special modes of life are not much more important than those exhibited by animals inhabiting caves of comparative recent origin, such as Proteus or those living in the deep waters of the large lakes of Europe, which are also of no great antiquity, such as the air-breathing water-snails, which, from the necessities of deep-water life, have adapted their lungs to aquatic respiration. A long time has not therefore been required for these modifications to take place.

It has been, I believe, commonly assumed that the water of the ocean was originally fresh, or nearly so, and that it became gradually salter as the rivers brought into it salts as part of the products of denudation. But surely the primitive sea must have been highly charged with saline matters of all kinds.

Το

When the earth was still intensely heated, the whole of the water now on its surface must have been present as gas in its atmosphere, at first no doubt dissociated, but afterwards as aqueous vapour. Since if the sea-bottom and continents were smoothed down to a uniform level, the sea would still suffice to cover the entire earth to a depth of over 1,000 fathoms, aqueous vapour equal to a layer of water of that thickness must have existed in the atmosphere and have produced a pressure of more than a ton on the square inch at the earth's surface. this pressure must have been added that produced by all the other vapours with which the primitive atmosphere must have been filled. As the earth cooled the water condensed on the coolest spots from time to time, boiled, and rose as vapour again. Mr. Mallet conjectures that the first water formed on the earth's surface may have been even as hot as molten cast-iron. At last permanent seas were established. The waters of these heated to an intensely high temperature under great pressure must have dissolved salts in abundance from the freshly consolidated earth's crust, and being constantly in a state of ebullition as the pressure diminished at the surface with the growth of the seas, or the temperature of the earth's surface varied in different places, must have taken up vast quantities of rock-matter in suspension and become thickly charged with volcanic mud. Intensely hot rain must have fallen on the land and have washed down more salts and mud into the sea. The whole ocean must have consisted of a vast mass of seething mud.

It must have required a protracted period for the ocean to become clear, and for its deposit, which was perhaps somewhat like the present deep-sea red mud, to settle, and possibly the deeper water long remained uninhabitable, being overcharged with various gases and salts and suspended mud. In connection with the question of the probable development of the earliest forms of life in heated water holding abundant salts and gases in solution, it is of importance to note that various algae at present

Friday Evening Lecture delivered at the Royal Institution on March 5, by H. N. Moseley, F.R.S., Assistant Registrar of the University of London. Continued from p. 572.

R. Mallet "On the Probable Temperature of the Primordial Ocean of our Globe." Quart. Journ. Geol. Soc., 1880, p. 115.

thrive in very hot mineral springs in various parts of the world.1

To this original deposit of mud on the deep ocean floor the deposits which have since been formed possibly bear but a slight proportion in thickness, for it must not be forgotten that all the Globigerina mud and other organic deposits now in course of formation on the sea bed are ultimately derived from the land. The Globigerinæ merely distribute the lime washed down by the rivers more evenly over the ocean floor, by concentrating it in the substance of their shells. The organic muds are in their origin products of denudation, and if the whole land now above the sea were washed into the ocean and evenly distributed a deposit of only about 500 feet in thickness would result.

FIG. 15.-Umbellula Greenlandica.

I shall, in conclusion, speak of some of the physiologiDeep-sea animals, cal conditions of life in the deep sea. as a rule, have either no eyes at all or have very large eyes. As an example may be cited the crustacean, Astacus zalencus, most closely allied to the common crayfish which Prof. Huxley has lately made illustrious. It is from 450 fathoms. It has no eyes at all, but one of its nippers is extraordinarily long and delicate, and possibly the animal uses it to feel its way with, as a blind

man uses his stick. There are also abundant hairs on the animal's surface, which are probably organs of touch. Many deep-sea crustacea, however, and fish have very large eyes indeed, evidently for the purpose of making * See "Notes by a Naturalist," pp. 36, 383, 410.

use of some small quantity of light which must exist in all depths. In the absence of sunlight the only other source of light must be the phosphorescence of certain of the deep-sea animals themselves. Dr. Carpenter, Sir Wyville Thomson, and Mr. Gwyn Jeffreys came to this conclusion after some of their early deep-sea dredgings. There can be little doubt of its correctness.

Here (Fig. 16) is a deep-sea Alcyonarian, Umbellula

FIG. 17-Pentacrinus maclearanus, Wyville Thomson.

Greenlandica, so named because it was first obtained off, Greenland, being, like the deep-sea fish I exhibited, an example of a deep-sea form extending into shallow water in high latitudes. Umbellula consists of a bunch of polyps supported on the end of a long flexible stem, which is cut off short in the figure. This specimen was from 2,175 fathoms between Madeira and the Spanish coast. When it came to the surface it emitted a most brilliant phos

phorescent light, as did also many allied forms dredged in deep water. No doubt these animals, like their congener in shallow water, emit light in the deep sea; and the deepsea animals with eyes probably congregate round them cr grope their way in the gloom from one bunch to another as they lie scattered over the bottom, just as we half-feel, half-see our way from lamp-post to lamp-post at night in a London fog. Some lose their way, as we do sometimes,

and get into shallow water, and a good many deep-sea animals have been from time to time picked up near the shores at Madeira and elsewhere, and have found their way into museums as great 30 rarities.

No doubt the sense of touch is the one mainly relied on by most deep-sea animals. Very many are provided with special organs of touch, such as long hairs, or in the case of fish enormously long fin-rays. Unfortunately we did not examine the organs of hearing of any of the deep-sea animals which we dredged. Nearly all were far too precious to be dissected. Possibly some of the animals have the sense of hearing highly developed.

There is plenty of oxygen for respiration in the deep sea. Mr. Buchanan found that water from even 4,475 fathoms contained 4:06 cubic centimetres of oxygen to the litre, nearly as much as at the surface, where, however, the amount varies greatly, rising to as much as 7 cubic centimetres per litre. The smallest amount observed was 6 of a cubic centimetre per litre in a depth of 2,875 fathoms. Even this amount would probably support life, for Humboldt and Provençal showed that tench could still breathe, though with difficulty, in water containing only one-third of that quantity of oxygen.

Life must be very monotonous in the deep sea. There must be an entire absence of seasons, no day and night, no change of temperature. Possibly there is at some places a periodical variation in the supply of food falling from above, which may give rise to a little annual excitement amongst the inhabitants.

There being no plants in the deep sea except parasites, the ultimate sources of food must be derived entirely from above, from the falling to the bottom of dead surface animals and plants, and of the débris washed from the shores. Seawater acts as a most efficient preservative of animal tissues, and possibly at no very great depths and at the deep-sea bottom Bacteria may be entirely absent, so that decomposition in the form in which we are commonly acquainted with it does not there take place at all.

From experiments which I made on the rate of sinking of a dead Salpa I found that it would reach the bottom at 2,000 fathoms in four days, in which time it would even at the surface be hardly decomposed at all. It would thus afford good food to the bottom animals.

A large quantity of shore débris and vegetable matter carried down by rivers reaches the deep-sea bed. We found leaves, branches, and fruits in deep water, and one of the latter had its interior still fresh, and was full of animals feeding upon it. Mr. Agassiz found in depths of

over 1,000 fathoms orange and mango leaves, sugar-cane, nutmegs, and land-shells in profusion, and many hermitcrabs actually inhabiting tubes of bamboo instead of shells. We found a land-crab once in 450 fathoms; no doubt it had drifted out hanging on to some floating object, and had sunk to the bottom, being unable to swim. The numbers of animals to be found in the deep sea decrease rapidly in proportion as the depth exceeds 2,000 fathoms, and very probably the greatest depths have very little life in them. We at present know only of Rhizopods as inhabiting them. Even in depths of less than 2,000 fathoms the shallower waters are most productive, and probably the deep-sea fauna is most abundant not far from the upper limit of its range. It is here, in from 200 to 400 fathoms, that such forms as Pentacrinus are most numerous. Here in many places these animals, a few years ago the greatest of rarities, cover the sea-bottom, thickly set like trees in a forest, still as abundant as ever they were in geological times. It is probably scarcity in supply of food which limits the quantities of animals in great depths. No doubt food is always most abundant near the coasts.

Some animal forms appear to be dwarfed by deep-sea conditions of life. Others attain under them gigantic proportions. It is especially certain crustacea which exhibit this latter peculiarity, but not all crustacea, for the crayfish-like forms in the deep sea, are of ordinary size. I have already referred to a gigantic Pycnogonid dredged by us. Mr. Agassiz dredged a gigantic Isopod eleven inches in length. We dredged also a gigantic Ostracod. The increase in size depends probably on lack of enemies rather than on abundance of food.

The unhappy deep-sea animals have not escaped their parasites in their cold and gloomy retreat. The tube of the Cerianthus, of which I showed a figure, was full of Nematode worms. Crinoids are beset by a Myzostomum, and one deep-sea shrimp was found with a parasitic Gordian worm coiled up inside its body, filling it almost entirely. I have already described the vegetable parasites

of corals.

The existence of colour in deep-sea animals is a very interesting fact. Some of the animals, as for example many of the fish, have lost their colour in the dark, and have become simply black or white. Others are most brightly coloured, having retained through countless generations the colouring of their shallow-water ancestors. Some, like the deep-sea shrimps, which are almost always of an intensely bright red colour, seem to have developed a special amount of colouring in the depths. The phosphorescent light of deep-sea Alcyonarians, when examined by the spectroscope, is seen to consist of red, yellow, and green rays only. Hence only these colours would be effective in the deep sea, and no blue animals were dredged from any considerable depths.

Colouring matters however need not always have a decorative object in existence. Certain chemical compounds formed within the bodies of animals for various physiological purposes may happen to have a peculiar action on light so as to be coloured, but this colourproducing property may be a waste or bye-product, so to speak, and only be turned to advantage by certain animals as a subsequent improvement. The fact that our own blood is red is probably an instance in point. In most mammalia the blood is entirely in the dark throughout the animal's life, and never acts on the light so as to exhibit its colour, which is to these animals useless. In ourselves the colour has been turned to advantage for decorative purposes. The colouring matters of some deep-sea animals may thus be retained, because the substances yielding the colours are necessary for the wellbeing of the animals, and these substances happen to be coloured, just as sulphate of copper is blue, though chemists seldom employ it because of its colour.

As an example of the vividness of deep-sea colouring

matters, may be cited that of Pentacrinus. Here (Fig. 17) is a Pentacrinus dredged from 400 fathoms near the Azores. The animal may be briefly described as a starfish turned upside down and set on a stalk. When freshly dredged Pentacrini are put into spirit, their colouring matter dissolves out and tinges the spirit of an intense purple red. (The light was thrown upon the screen through a solution of this colouring matter in spirit, from specimens of Pentacrinus dredged in 650 fathoms.) The colour is a most beautiful red. It is red when acid, but when a few drops of ammonia are added to it, it turns to an intense green. Very probably this colouring matter is as ancient as the genus Pentacrinus itself.

The colouring matter yields a well-defined absorption spectrum. The acid solution (Fig. 18) shows two dark bands in the yellow and a faint one in the green, and the alkaline green fluid a dark one in the red, with two fainter

FIG. 18.-Spectra of the acid and alkaline solutions of the colouring matter of Pentacrinus in spirit. The acid spectrum above and the alkaline below. The fine lines are solar lines.

ones in the yellow and green. By means of this double set of lines this colouring matter can be almost certainly identified, although its chemical composition has never been investigated.

A good many other colouring matters of deep-sea animals give well-marked absorption spectra, and can be similarly identified, and it is most interesting to find that the very same colouring matters found in deep-sea animals occur also in allied shallow water and surface forms. Thus numerous deep-sea corals and sea-anemonies are tinged of a madder-red colour by the same pigment, which is abundant in many jelly-fish which float on the sea surface. The red colouring matter of the deep-sea shrimps is also identical with that which occurs in smaller quantities in nearly all the microscopic crustacea with which the sea surface is crowded.

In conclusion I would merely impress upon you again that the most important subject now remaining to be investigated with regard to deep-sea life is the range of life at the various depths between the surface and the bottom of the ocean.

A MAGNETO-ELECTRIC GYROSCOPE

THIS is the name of an apparatus invented by M. W. de Fonvielle, editor of Electricité, after having witnessed an experiment by M. D. Lontin. This gyroscopic machine was exhibited by M. de Fonvielle to the Royal Society on the 15th inst., when a paper by him was read by Prof. Stokes. The instrument can now be seen at Elliot's, St. Martin's Lane.

The object of the apparatus is to demonstrate new properties of induction currents brought into play in a magnetic field, and which give a continuous rotatory motion to movable pieces of iron of various forms (Fig. 1). The apparatus consists essentially of a galvanometric frame of any shape. In the first model which has been brought over to England the galvanometric frame is a rectangular one, above which is placed a horseshoemagnet, supported by a vertical axis round which the

1 See H. N. Moseley, "On the Colouring Matters of Various Animals,

especially Deep-sea Forms" (Quart. Journ. Micro. Sci., vol. xvii., new ser.,

p. 1).