Who

from their extent-must have been worked for centuries. the workers were, no one can tell. They seem to have known nothing of the smelting of copper, for there are no traces of molten copper. What they sought were pieces that could be fashioned by cold hammering into useful articles and ornaments. They understood the use of fire in softening the rocks to enable them to break away the rock from the masses of copper. They could not drill, but used the stone hammer freely. More than ten cart-loads of stone hammers were found in the neighbourhood of the Minnesota mine. In one place the excavation was about 50 feet deep, and at the bottom were found timbers forming a scaffolding, and a large sheet of copper was discovered there. In another place, in one of the old pits, was found a mass of copper weighing 46 tons. At another point the excavation was 26 feet deep. In another opening, at the depth of 18 feet, a mass of copper weighing over 6 tons was found, raised about 5 feet from its native bed by the ancients, and secured on oaken props. Every projecting point had been taken off, so that the exposed surface was smooth. Whoever the workers may have been, many centuries must have passed since their mines were abandoned. Their trenches and openings have been filled up, or nearly so. Monstrous trees have grown over their work and fallen to decay, other generations of trees springing up. When the mines were rediscovered, decayed trunks of large trees were lying over the works, while a heavy growth of live timber stood on the ground.

THE last two parts of the Izvestia of the Russian Geographical Society (vol. xxvii., 3 and 4) contain M. Grum-Grzimailo's report on his journey to Central Asia, and General Tillo's calculations of the heights determined by the Russian traveller during his journey. The report, which adds little to the information given in the explorer's letters, is accompanied by a map embodying the results of the extensive surveys made by the two brothers in the Eastern Tian Shan, the Hashun Gobi, the Barkul

oasis, and the region in the south-east of it, as far as the 36th degree of latitude and the 72nd degree of longitude. It was already known that during this journey the brothers GrumGrzimailo had discovered, some fifty miles to the south-east of Turfan, a depression situated between the two chains of the Eastern Tian Shan and the Kuruk-tag Mountains, the level of which proved to be very near to the sea-level, or even below it. At the spot, Lukchin-chir, their barometer rose (on October 27) to 7717 mm. On the same day, the pressure of the atmosphere, reduced to the sea-level, attained 784 mm. at Krasnoyarsk, 787.7 mm. at Yeniseisk, 774 mm. at Irkutsk and Tomsk, and 767 mm. at Przevalsk and Narynsk; so that there may be some doubt as to the pressure in the latitude and longitude of Lukchin-chir (at the sea-level) really being 767 mm., as adopted by General Tillo, which would give for that spot 50 metres below the level of the sea. But the possible error cannot be very great, and we thus have, between the two above-named

take care of the ornithological collection, offered to send it to Mr. L. Stejneger, of the U.S. National Museum, in instalments for identification and study, and the proposal was gladly accepted. Dr. Stejneger has made some progress with the work, and has just issued "Notes" in which he presents the results of his examination of the first instalment. He has had the satisfaction of finding "quite a number of interesting additions to the Japanese avifauna.”

We have received Nos. 7-9 of vol. i. of "Illustrations of the Flora of Japan, to serve as an Atlas of the Nippon-Shokubutsushi," by Tomitaro Makino, a monthly publication, brought out in Tokyo, apparently somewhat on the plan of the "Icones Plantarum." Each number contains about six plates (uncoloured), with descriptions, of new or remarkable species, natives of Japan. The drawings are exceedingly well done, and the descriptions (in English) would compare favourably, in accuracy and completeness, with those of some works published in this country. The species described appear to be taken at random, those in the same number having no affinity with one another.

MESSRS. BAILLIÈRE, TINDALL, AND COX have issued the fifth edition of the "Manual for the Physiological Laboratory," by V. D. Harris and D'Arcy Power. The work has been enlarged, the increase being due mainly to the more detailed account which has been given, for junior students, of microscopes and their properties; and to the description, for senior students, of the latest methods of histological research. The parts relating to physiological chemistry have been thoroughly revised, and many additional illustrations have been inserted.

MR. JAMES STIRLING, Assistant Government Geologist, Victoria, has published at Melbourne some valuable and interesting notes on the hydrology of the Mitta Mitta. The following are the leading conclusions to which he has been led

by his observations :-(1) That there is considerable inequality

in the amount of rainfall over different portions of the same watershed area in each of the various streams flowing from the Australian Alps, the Mitta Mitta being cited as an instance of this; and that as the recording stations at present established are all below the normal line of cloud flotation (under 4000 feet), where the rainfall is greater, the actual quantity which falls in the several watershed areas is really greater than that shown in the records. (2) That the low percentage of discharge to rainfall is due in all probability to a complexity of causes, among which may be cited the excessive evaporation in certain areas, largely due to the great range of temperature; the different heat-radiating powers of different rock-masses; and percolaformations, &c.; and, in some areas, the absorption by certion along fault lines, contacts of the igneous and sedimentary tain species of the prevailing eucalyptus vegetation. (3) To determine the actual quantity of rainfall and the causes affect

which is very near to the level of the ocean.

MR. L. STEJNEGER describes, in the Proceedings of the American National Museum, a new North American lizard of the genus Sauromalus. It is very large, the total length of four specimens averaging 540 millimetres. This enormous lizard is closely allied to the much smaller species which inhabits the arid regions of the mainland to the north of the Gulf of California, viz. Sauromalus ater, with which it has been confounded. It may be readily distinguished by the characters given in Mr. Stejneger's diagnosis.

SOME time ago the Educational Museum of Tokyo was abolished, and the collections were transferred to the Science College of the Imperial University. Dr. I. Ijima, Professor of Embryology and Comparative Anatomy, who volunteered to

meteorological stations at the higher altitudes in the Australian Alps. (4) And in order to supply further trustworthy data, it is, Mr. Stirling thinks, imperative that a system of complete topographical survey should be instituted.

THE Annual Report, for 1888-89, of the Geological and Natural History Survey of Canada has been issued. It forms the fourth volume of the new series, and includes reports and maps of various investigations and surveys. The volume opens with summary reports, by Mr. Alfred R. C. Selwyn, the Director, on the operations of the Geological Survey for the year 1889. Then come the following reports: -On a portion of the west Kootanie district, British Columbia, by G. M. Dawson; an exploration in the Yukon and Mackenzie basins, by R. G. McConnell; exploration of the glacial Lake Agassiz in Manitoba,

by Warren Upham; the mineral resources of the province of Quebec, by R. W. Ells; the surface geology of Southern New Brunswick, by R. Chambers; chemical contributions to the geology of Canada from the laboratory of the Survey, by G. C. Hoffmann; mining and mineral statistics of Canada, by H. P. Brumell; division of mineral statistics and mines, by E. D. Ingall and H. P. Brumell; annotated list of the minerals occurring in Canada, by G. C. Hoffmann.

THE administration of forests seems to be, on the whole, one of the most satisfactory departments of public activity in India. Dr. Ribbentrop, in his report for the year 1889-90, states that over 4200 square miles were added to the area of forest estates under control, thus bringing the total area up to nearly 105,500 square miles. The gross revenue exceeded 153 lakhs of rupees, giving a surplus over expenditure of nearly 73 lakhs, or an increase in a single year of 15 lakhs. The surplus in 1885 was only 41 lakhs. It is believed that this rate of increase may be maintained, as the rich forests of Upper Burma have still to be opened out.

In a recent communication from Alta Verapaz, a department in Guatemala (Met. Zeit.), Dr. Sapper describes the climate. The position is on the north slope of a hill-range stretching east and west, and the large rainfall (it has a rainy season in winter, as well as that in summer common to the whole of Central America) apparently affects the frequency of earthquakes. For the district is of limestone and dolomite, and honeycombed with caverns and subterranean watercourses, and heavy rains lead to a collapse of such cavities, so that towards the end of the summer rain season, and still more towards that of winter, the number of earthquakes and tremors is distinctly increased. The winter of 1889-90 had unusually heavy rains, and the earthquakes were also unusually numerous (seventeen in 1890 as against five the previous year).

A PAPER upon the sulphides of boron is communicated by M. Paul Sabatier to the September number of the Bulletin de la Société Chimique. Hitherto only one compound of boron with sulphur has been known to us, the trisulphide, BS, and concerning even that our information has been of the most incomplete description. Berzelius obtained this substance in an impure form by heating boron in sulphur vapour, but the first practical mode of its preparation in a state of tolerable purity was that employed by Wöhler and Deville. These chemists prepared it by allowing dry sulphuretted hydrogen gas to stream over amorphous boron heated to redness. Subsequently a method of obtaining boron sulphide was proposed by Fremy, according to which a mixture of boron trioxide, soot, and oil are heated in a stream of the vapour of carbon bisulphide. M. Sabatier finds that the best results are obtained by employing the method of Wöhler and Deville. The reaction between boron and sulphuretted hydrogen only commences at red heat, near the temperature of the softening of glass. When, however, the tube containing the boron becomes raised to the temperature, boron sulphide condenses in the portion of the tube adjacent to the heated portion; at first it is deposited in a state of fusion, and the globules on cooling present an opaline aspect. Further along the tube it is slowly deposited in a porcelain-like form, while further still the sublimate of sulphide takes the form of brilliant acicular crystals. The crystals consis of pure B,S,; the vitreous modification, however, is usually contaminated with a little free sulphur. Very fine crystals of the trisulphide may be obtained by heating a quantity of the porcelain-like form to 300° at the bottom of a closed tube whose upper portion is cooled by water. The crystals are violently decomposed by water, yielding a clear solution of boric acid, sulphuretted hydrogen being evolved. On examining the porcelain boat in which the boron had been placed, a non volatile

black substance is found, which appears to consist of a lower sulphide of the composition B,S. The same substance is obtained when the trisulphide is heated in a current of hydrogen; a portion volatilizes, and is deposited again further along the tube, while the residue fuses, and becomes reduced to the unalterable subsulphide BS, sulphuretted hydrogen passing away in the stream of gas.

Two selenides of boron, B,Se, and B,Se, corresponding to the above-described sulphides, have also been prepared by M. Sabatier, by heating amorphous boron in a stream of hydrogen selenide, H.Se. The triselenide is less volatile than the trisulphide, and is pale green in colour. It is energetically decomposed by water, with formation of boric acid and liberation of hydrogen selenide. The liquid rapidly deposits free selenium, owing to the oxidation of the hydrogen selenide retained in solution. Light appears to decompose the triselenide into free selenium and the subselenide B.Se.

SILICON SELENIDE, SiSe,, has likewise been obtained by M. Sabatier by heating crystalline silicon to redness in a current of hydrogen selenide. It presents the appearance of a fused hard metallic mass incapable of volatilization. Water reacts most vigorously with it, producing silicic acid, and liberating hydrogen selenide. Potash decomposes it with formation of a clear solution, the silica being liberated in a form in which it is readily dissolved by alkalies. Silicon selenide emits a very irritating odour, due to the hydrogen selenide which is formed by its reaction with the moisture of the atmosphere. When heated to redness in the air it becomes converted into silicon dioxide and free selenium.

THE additions to the Zoological Society's Gardens during the past week include a Macaque Monkey (Macacus cynomolgus 8) from India, presented by Mr. G. E. Lidiard; two Senegal Touracous (Corythaix persa), a Madagascar Porphyrio (Porphyrio madagascariensis) from West Africa, presented by Mr. J. B. Elliott; a Blue-fronted Amazon (Chrysotis æstiva) from Brazil, presented by Mrs. H. R. Warmington; two Puff Adders (Vipera arietans) from South Africa, presented by Messrs. Herbert and Claude Beddington; two Tree Boas (Corallus hortulanus) from St. Vincent, W.I., presented by H. E. the Hon. Sir Walter F. Hely Hutchinson, K. C.M.G.; a Tree Boa (Corallus hortulanus) from Demerara, presented by Mr. J. J. Quelch, C.M.Z.S.; a Black-headed Lemur (Lemur brunneus) from Madagascar, a Brown Capuchin (Cebus fatuellus) from South America, a Black-headed Caique (Caica melanocephala) from Demerara, a Red and Blue Macaw (Ara macao) from Central America, deposited; a Black-headed Caique (Caica melanocephala) from Demerara, purchased.

OUR ASTRONOMICAL COLUMN.

OUTBURST OF DARK SPOTS ON JUPITER.-Attention has been called by several observers to a number of dark spots which have appeared lately on the first belt north of the north equatorial belt of Jupiter, in about latitude 20. Mr. Denning derived a period of rotation of 9h. 49m. 27'2s. from his observations of one of these objects between August 21 and September 15 (Observatory, October 1891). A change then occurred, for this spot, and others near it, were found to have a rotation period of 9h. 49m. 44 2s. from September 15 to October 15. This sudden change of 17 seconds in the rate of motion of a region of some extent is most remarkable. A series of photographs of Jupiter were taken at Lick Observatory in August, which, according to Mr. Stanley Williams, "are of such a degree of excellence that an examination of them is almost like looking at the planet itself" (Observatory, November 1891). These photographs show six or seven dark spots, and a comparison of them with a sketch made about one rotation later clearly indicates a displacement of the spots with reference to the great red spot,

At

owing to the more rapid movement of the belt in which they occur. Prof. E. E. Barnard observed the spots so early as May last (Astronomische Nachrichten, No. 3063). He found in September that they were decreasing their longitudes about 10° daily. this rate they would describe a complete rotation round Jupiter, relative to the great red spot, in about 36 days. The daily loss derived from Mr. Denning's observations in August and September would bring the two spots in conjunction in about 39 days.

WOLF'S PERIODIC COMET.-The following ephemeris is from one given by Dr. Thraen in Astronomische Nachrichten, No. 3064 :

1891.

Nov. 14

17 20

Dec. 2

5

Ephemeris for Berlin Midnight. Right Ascension.

Declination.

Brightness.

10'2

9'3

8.3

7'4

23

26

29

12 17 51 12 58 22

23 37

THE ELEMENTS OF THE MINOR PLANETS.-The Vierteljahrschrift der Astronomischen Gesellschaft (first volume) contains two interesting compilations, on the planets discovered in the year 1890, and on the appearances of comets in the same year. The first paper is contributed by Dr. Paul Lehmann, and informs us that no less than fifteen new members of our minor planet system were discovered last year between February 20 and November 14. In the table that follows a summary of all the days on which each individual planet was observed is given, and this is succeeded by another which shows their chief elements. By combining the elements of some of the old planets with those of the new ones, some striking combinations are thus brought to light, of which we give the two following cases, in which the new planets are 292 and 288 :

planets can attain. In the last form the tabulation is so arranged that the following numbers can be directly seen :-(1) The number of oppositions in which, up to the present time, places have been found, with the number of appearances since observed. (2) The number of every known opposition in which the planet has been observed. (3) Every planet to which the foregoing statement refers. (4) The number of these planets.

SOME EXPERIMENTS MADE WITH THE VIEW OF ASCERTAINING THE RATE OF PROPAGATION OF INDUCED MAGNETISM IN IRON.

THE question, considered in a simple form, may be put thus: Suppose a magnet were suddenly brought up to one end of a long iron rod, what length of time intervenes between the occurrence of magnetization at the near end and at the far end? Everyone, probably, would at first be inclined to say that the speed along the bar would undoubtedly be about the same as the velocity of light, and this supposition would naturally follow if the energy to places along the bar be supposed transmitted through the surrounding space; but, on the other hand, the speed may be much less if the energy of magnetization is transmitted from particle to particle in the iron-the orientation of the molecular magnets being, as it were, passed from each to the next along the bar. In such case we would, of course, expect the velocity of propagation to be comparable in speed with that of molecular phenomena rather than that of disturbances in the ether.

The velocity of sound, with which we may, perhaps, compare it, is in iron about 16,coo feet per second. The transmission of sound resulting from vibratory movement can be said to depend on the mass of the molecule, and on the mutual forces keeping the molecules in position; while the rate of propagation of a magnetic disturbance of the kind supposed would depend on the moment of inertia of the particles (assumed to be molecular magnets) round their axes of rotation, and on their mutual magnetic moments.

The propagation of such a disturbance can be observed in Prof. Ewing's magnetic model. The model, which consists essentially of a great number of small compass needles placed within each other's action, but not near enough to touch, can be disturbed at one place by bringing a magnet near, or otherwise. The disturbance then is seen to spread throughout the model, much in the same manner as we have suggested a magnetizing disturbance to be propagated in iron.

The method proposed to test matters depended upon the principle of the interference of waves travelling in opposite directions observed through the production of stationary waves.

Thus, if a bar of soft iron have two coils of wire placed one at each end, and if the same alternating current be passed through both coils, disturbance of opposite signs travelling in opposite directions along the bar should interfere, provided the rate of alternation and the length of the bar are chosen suitable to the rate of propagation.

It was proposed to detect the nodes or places of interference by means of a telephone in circuit with a third coil which could be slid along the bar.

Instead of employing two alternating coils, the bar can be bent round to form a ring, and one coil will be then sufficient.

a

Some preliminary experiments with a straight bar having given faint indications of the existence of places of minimum intensity, closed magnetic circuits or rings, formed of great number of turns of soft iron wire, were then tried with more decided results. When the alternating coil was in certain positions on the ring the telephone coil could be placed at points where no sound, or if any very slight, could be heard-the sound reaching a maximum in places somewhere between these points. These nodes and internodes occupied about half the ring-the opposite half of the ring from that in which the alternating coil lay. approaching nearer the alternating coil, apparently the very unequal length of the paths prevented any effect being observed. It was without difficulty ascertained that these were not the Two rings were made of No. 21 soft iron wire, one about 10 feet and the other 14'5 feet in circumference. Both had 8 pounds of wire wound on. The wire used in a third ring was No. 32 This ring was about 12 feet in circumference. There was about 4 miles of wire put on. The wire of this and the 14-feet ring was well coated with shellac before winding, so as to minimize Foucault currents.

On

nodes looked for, because the distances between them remained nnaffected on changing the rate of alternation. The distances from node to node also were found to measure different amounts (though on the whole there was a decided tendency towards regularity). The average distance apart of the nodes in the different rings tried lay between 10 and 18 inches.

The occurrence of the nodes might have been very well attributed to the ring being locally irregular in its susceptibility to induction, but for the irreconcilable fact that the effects on either side of a node were found to be of opposite phase, just as it would be, were the phenomenon due to stationary interference waves.

This was ascertained by means of two coils connected in the same sense in series with the telephone. When these coils were arranged at places of equal intensity, one on each side of a node, no sound was to be heard in the telephone, the effects neutralizing one another. A commutator, to throw in the coils singly or together as desired, is convenient for making this experiment.

From this, one would naturally assume that the currents induced on either side of a node must be of opposite sign, seeing that they neutralize each other in the telephone; but experiments with the galvanometer show it not to be the case. Το test this, the galvanometer is connected up through a com

mutator, arrangement fixed to the originator of the primary current in such a way as only to admit of the currents induced in one direction passing. Tried in this way, no difference in the direction of the current on either side of a telephone node was found, or, indeed, any trace of a minimum effect at these points. The thing can also be tested by means of a ballistic galvanometer, and a reversing key with battery, for, with a reversing key and telephone, the nodes, which are quite independent of the speed, are to be found, as well as the opposite phase effect. The ballistic galvanometer gives no indication of there being any difference at the nodes from elsewhere, and the deflection everywhere is in the same direction.

It was thought that perhaps the telephone effect was in some way connected with the fact that the form of the alternating current was not a simple wave or sign curve, owing to the method employed in producing it. This consisted of a rotating commutator, which threw in circuit alternately two cells connected up singly and in opposite directions. For this reason, the effect, when using a small alternating machine with about 40 alternations per second, was compared, and was found to be in no way different. Also what must have been a very regular variable current of the simple harmonic type was procured by means of a microphone and an organ-pipe. This gave like results.

One is thus left apparently to suppose the sound in the telephone to be due to a peculiarity in the character of the curve representing the rise and fall of the current, probably something of the nature of a subsidiary oscillation; this subsidiary oscillation being absent at the nodes, and of opposite sign on either side.

As mentioned before, it is necessary for the alternating coil to be placed at definite positions, in order that the system of nodes and internodes should occur. These positions of the alternating coil are at about the same average distance apart, and are of very much the same character with respect to regularity as the nodes of the telephone coil. In fact, if the alternating coil and the telephone coil change places round the ring, the best position for the alternating coil will always be between two nodes, and the nodes will be found situated between two old positions of the alternating coil. If the alternating coil be placed at a point where a node was found in some other position of the alternating coil, the system of nodes and internodes generally completely disappears, and now on moving the telephone coil round the ring the intensity uniformly diminishes until the diameter is reached, and then increases round the other half of the ring. This gives the phenomenon a distinctly resonant character. The induced current, as observed by a galvanometer, is always of the latter character-that is to say, a uniform fall, and then a rise on going round the ring.

As a rule the permanent magnetism of these large rings is irregular, and apparently apt to change frequently. A determination of the permanent magnetism was easily made by means of one of the coils connected with a ballistic galvanometer. By moving this through a given amount at a time, say an inch, and noting the throw of the needle, one was able to plot out a representation of the state of the permanent magnetism. In this way, places where no throw occurs were found, while to either

side of such a point the throw changed sign. It was sometimes found that there was a decided tendency for the position of no throw to occur between two telephone nodes, the throw changing sign on either side of these points. But further experiments showed that this arrangement of the permanent magnetism was probably accidental, and due to the very currents employed in making the telephone observations. For when only very feeble currents had been used on a ring, these consequent poles were

absent.

It is possible, as one would expect, to artificially make a minimum intensity position, at any point on a ring, by winding on a few turns of thick copper wire. But the fact that the phases on either side of such a point (found as before by means of two coils in circuit with a telephone) are the same, precludes the idea that the nodes can be due to Foucault currents.

Obviously, however, the phenomenon depends on some permanent peculiarity round the ring which happens to occur fairly regularly. What this peculiarity is, or how it is brought about, I have not yet been able to discover. FRED. T. TROUTON.

OYSTERS AT THE ANTIPODES.

SO much attention has been given in England to the various questions connected with oyster-fisheries that it may be cf interest to note some facts relating to the oyster-fisheries of our Australian kinsfolk. The subject was admirably dealt with in a lecture delivered by Mr. Saville-Kent before the Christchurch meeting of the Australasian Association for the Advancement of Science. This lecture is entitled "Oysters and OysterCulture in Australasia," and has been published separately.

Mr. Saville-Kent devotes attention chiefly to Australia and Tasmania, as, at the time when his lecture was prepared, he had not had an opportunity of personally studying the question in New Zealand. Beginning with Tasmania, where for five years he was officially connected with the oyster-fisheries, he points out that the oyster of Tasmania corresponds closely with the type Ostrea edulis, produced and cultivated in British waters. Formerly, this oyster was so abundant in Tasmanian waters, that, according to the report of a Royal Commission of Fisheries in 1882, about twenty years previously a quantity representing at current prices a retail value of no less than £90,000 had been exported in a single year to Victoria and New South Wales. At that time, oysters were so plentiful that it was a common practice to burn them in large quantities for the purpose of making lime. The strain was, of course, too severe, and by and by the Tasmanians found that, although there was still a demand for oysters, there was no longer a home-supply, and that it was necessary for them to go elsewhere for the commodity which they had so recklessly wasted. In 1884, when Mr. SavilleKent reached the colony, the oyster-fisheries of Tasmania had for some years been an obsolete industry. Profiting by the information which had been made accessible through the International Fisheries Exhibition and associated Conferences in London in 1883, and by Prof. Hubrecht's testimony as to the oyster-fisheries of the Schelde, Mr. Saville-Kent recommended the establishment, in suitable localities, of efficiently-protected Government reserves, upon which breeding-stocks of oysters of the best quality should be carefully cultivated and permanently retained. These reserves were to fulfil the double purpose of breeding-centres, from whence the surrounding waters might be restocked, and also of model oyster-farms, around which private beds might be established on similar lines. The scheme recommended being approved, sites formerly associated with the most prolific oyster production were selected. The operations were necessarily conducted on a very modest scale. Oyster stock, suitable for laying on the reserves, could be accumulated only by slow and laborious processes, and some 20,000 to 50,000 oysters represented the approximate numbers that were gradually collected and placed under cultivation. In order that the largest possible amount of spat produced by the oyster stocks laid down might be caught, various methods were adopted, the principle being that which has been followed with so much success by M. Coste on the west coast of France. In addition to dead oyster-shells, or cultch," which has, from the earliest days of oyster-culture, been recognized as representing a most natural and prolific catchment material for the adhesion of the spat, artificial collectors of various descriptions were introduced. In France, tiles cemented on their lower surfaces have been found

66

to constitute the most productive and economic collectors. In Tasmania, as in all the other Australasian colonies, tiles being much too expensive for such a purpose, a cheap and efficient substitute for them was effectually improvised out of the thin roughly-cleft boards known as "split palings," which can be produced in timber-producing districts at a cost of from 8s. to IOS. per 1000. These paling collectors are coated on their under surface with cement, a brick or stone is fastened underneath at each end to give them stability, and a wire loop secured through the centre of their upper surface forms a convenient handle by which they can be manipulated on shore or raised with a boat-hook from beneath the water.

The results have been most satisfactory. Last year oysters had become so plentiful at Spring Bay that the Hobart market was glutted, and the sale price was reduced 50 per cent. Thus an important industry has been revived, and there can be little doubt that by the due maintenance of the breeding-reserves the oyster-fisheries of Tasmania will be restored to more than their former prosperity. In accordance with Mr. Saville-Kent's recommendations, all holders of private oyster-beds in Tasmania are bound by the terms of their leases to retain a certain amount of breeding-stock-not less than 10,000 mature oysters to the acre-permanently on their oyster-beds. This regulation contributes materially towards the distribution of spat throughout the surrounding water, and to the re-establishment of the oysterfisheries upon a durable basis.

Referring next to Victoria, Mr. Saville-Kent says that the specific form of oyster indigenous to the Victorian coast-line is a so-called mud oyster, identical with that produced in Tasmanian waters, and to all outward appearance indistinguishable from the British native, Ostrea edulis. In former years vast quantities of this oyster were obtained from Western Port Bay, Port Albert, and Corner Inlet. Over-dredging, however, has reduced these prolific natural beds to the very verge of extinction, so that Victoria has for many years been dependent upon New South Wales, Queensland, South Australia, and New Zealand, for her oyster supplies. Some time ago Mr. Saville-Kent was invited by the Government of Victoria to make a tour of and report upon the fisheries of the colony, giving special attention to the practicability of reviving the oyster-fisheries. As a result of that tour of inspection, he strongly recommended the adoption, at Western Port and Port Albert more particularly, of the methods which had proved so effective in Tasmania. One such reserve with a very small stock of oysters was formed at Port Albert. Unfortunately, however, the Government omitted to make provision for periodical skilled supervision, and the reserve dwindled away. As Mr. Saville-Kent says, unless such reserves can be maintained in efficient working order, and the operations periodically required thereon be supervised by a practical ostreculturist, the money expended on their establishment is simply wasted.

At various parts of the Victorian coast-line, Mr. Saville-Kent observed considerable numbers of oyster-shells, evidently derived from deep water, that had recently been cast upon the shore by storms. He consequently predicted that more or less extensive beds would be found off the coast; and off-shore beds have in fact been since discovered. Mr. Saville-Kent points out that a most favourable opportunity is thus afforded for the restocking of the in-shore fisheries.

In New South Wales a separate species of oyster has to be taken into consideration. The commercial species of this colony is the rock oyster, Ostrea glomerata. At the same time a mud oyster, identical with or most closely allied to the Victorian and Tasmanian type, Ostrea edulis, occurs in some numbers upon the coast, but in consequence of the hitherto profuse abundance of the rock variety it has not been considered worthy of cominercial attention. In form and general aspect the New South Wales rock oyster somewhat resembles the Portuguese oyster, Ostrea angulata, and also the American Ostrea virgineana. With these two species it further corresponds in its breeding habits, which are essentially distinct from those of the English, Victorian, and Tasmanian mud oyster, Ostrea edulis. In the case of the Australian rock oyster there is no nursing of the young brood, which is turned out to shift for itself, not only in a shell-less but even in an unfertilized condition. Like the spawn of many fishes, these ova are fertilized in the water. They can be readily fertilized artificially, and Mr. Saville-Kent has found that four days after fertilization the shells, which make their appearance on the second day, become so dense that the embryo oysters can no longer support themselves in the water, but sink

un

to the bottom, where they assume their permanently fixed con dition. Such is the fecundity of this oyster that the rocks and every available hiding-place in the bays, estuaries, and inlets o the districts it affects become literally plastered with the embry brood; and until quite recently, artificial culture in the scientifi sense has in New South Wales been usually regarded as an profitable and unnecessary superfluity. Lately, however, the oyster-fisheries of the colony have been seriously damaged by a disease which either destroys the oyster or makes it unfit for food. Mr. Saville-Kent attributes this disease to the pollution of rivers. If he is right in this view, in support of which he has much to say, the oyster-growers of New South Wales will, as he says, have to make the most of the water area left to them where the water is pure. They may also have to turn their at tention to the cultivation of the New South Wales variety of the mud oyster.

In Queensland, as in New South Wales, the only oyster used in commerce is the rock variety, which may be said to attain its maximum development in both quantity and quality in the Moreton and Wide Bay districts. In these areas the species is so abundant that large consignments, above those required for home consumption, are exported to New South Wales and Victoria. The disease which has so seriously depleted the fisheries of New South Wales has not yet affected the Queensland beds. Mr. Saville-Kent thinks that this immunity is probably due to the circumstance that the Queensland oysterfisheries are chiefly located in bays and channels in close proximity to the open sea, from whence, even after heavy floods from the tributary rivers, they are speedily revived by an inflow of sea-water. He urges the Queensland authorities to preserve these tributary streams as far as possible from pollution by chemical or other noxious works, which if allowed to increase to any considerable extent cannot fail to exert a very deleterious effect upon both the oyster and all other fisheries of the bays into which the rivers flow. Artificial oyster-culture, with the exception of one or two small experiments, has been so far carried out in Queensland waters on the simple lines only of transporting the young brood or ware, locally known as "cultivation," from one locality and laying it down on ground where it will develop more speedily to maturity. Mr. SavilleKent believes, however, that it would be profitable to use split palings as spat collectors. One advantage possessed by this form of collector is the shelter from the sun's heat afforded to the young brood when left high and dry by the receding tide. Millions of the Australian rock oyster are destroyed annually through exposure to the overpowering heat of the subtropical sun in the early days of their attachment to exposed rocks near high-water mark. The overhanging ledges of larger rocks and the shady sides of stone jetties or embankments are invariably found to attract and support the greatest amount of oyster brood, and this shelter, which is naturally sought, plainly indicates the lines that may be most profitably followed in operations connected with the artificial cultivation of the species.

66

We may note that since Mr. Saville-Kent's lecture was published a report by him- on "Oysters and Oyster-fisheries of Queensland" has been issued by the Queensland Government. In this report, which is carefully illustrated, full details are given as to the conditions which must be specially taken into account by all persons connected with Queensland oyster-fisheries. Referring to the split paling collectors, Mr. SavilleKent emphatically repeats what he says in their favour in his lecture. After considerable experience he expresses his conviction that they are the most convenient and economic form for use in Australian waters, and that they may be characterized as an essentially Australian product. About half-tide mark represents the zone within which-at all times of the year, but especially in the months of February and August-they gather the most abundant harvest of spat. On their first attachment to the cemented collectors, the young oysters adhere to the cement by the entire surface of the attached shell. After attaining to about half an inch in diameter, the free edges of the shells begin to grow outwards, and this direction of their growth is continued until at an age of about six months they project an inch and a half or two inches from the collector. At this stage the young oysters may be easily detached with or without the cement, and be laid on the banks as ordinary "cultivation." The collectors may then be re-cemented and re-laid for the catchment of a second crop.

Of the oyster-fisheries of South and West Australia Mr. SavilleKent is not able, in his lecture, to give precise details. He says,