The next session of the Academy will be held at Northampton, Mass., commencing on the 7th of August.

2. Note on Illumination of opake objects under the Microscope; by H. L. SMITH, Kenyon College.-In several scientific Journals of England, the little contrivance first described by me in the September No. of this Journal, 1865, is noticed and variously commented upon. With an apparent unwillingness to acknowledge any merit outside of themselves, the writers of these notices have dwelt especially upon certain fancied improvements, made by Messrs. Powell & Leland and Smith Beck & Beck, as the really valuable parts of the invention. Especially is this the case with the slight notice in the January number of the "Quarterly Journal of Microscopical Science," and the more extended one in the January number of the "Intellectual Observer," where the substitution of a glass plate for the metallic reflector, is spoken of in the highest terms. Now if my article had been read, these writers would have seen that this substitute had been tried, and abandoned by me. Even if it is an improvement and I have misjudged, still it is not original with the celebrated opticians who are so lauded for the invention. It is not true, as stated in the notice which is quoted from the "Reader" in the last number of this Journal, p. 283, that the metallic reflector cuts off half the pencil; an assertion which is also made in the "Microscopical Journal." Less than one-third, is amply sufficient to give a much stronger illumination than the whole of the glass substitute proposed; and with this great advantage, that the fog, or glare, which attends central illumination, may all be eliminated; and, upon diatoms especially, a vastly superior illumination may be obtained. The improved "Illuminators" are now furnished with an extra movable diaphragm above the illuminating reflector, which, although it diminishes the angle somewhat, greatly improves the definition, by prevention of irradiation when the object is very brilliant; it leaves however the whole angle effective for illumination. I certainly would be the last one to object to any real improvement which the English opticians might make; but do protest against being entirely ignored, as in the number of the "Microscopical Journal" for January, 1866, where a contrivance, already described by me, is so carefully alluded to, that no one would for a moment suppose that any credit was due except to Messrs. Powell & Leland, and Smith & Beck; the very slight allusion to the "American contrivance" being a disparaging one, and stating an untruth. How far Messrs. Powell & Leland and Smith & Beck are responsible for this does not yet appear. In justice I must except the notice in the Chemical News which is more candid. It is painful to be obliged to make these remarks, and most sincerely it is to be hoped that no further occasion will be given for complaint. England can well afford to be generous.

3. New Eruption of Mauna Loa; by Rey. TITUS COAN. (Editorial correspondence, dated Hilo, Feb. 27, 1866.)-Another eruption has recently commenced on Mauna Loa. The light was first seen on the night of the 30th Dec., 1865, at the very summit of the mountain. From that day to the present the eruption has continued with varying intensity. Sometimes the light is quite brilliant, shedding a glow over all the higher portions of the mountain, sending down its reflection upon our

town and landscape, and throwing its ruddy sheen upon the clouds. In the day time the smoke goes up like the smoke of a great furnace.

It is not, however, at all times equally active, and occasionally we imagine that it has become extinct. But we are soon undeceived by new manifestations, sometimes appearing as if the molten lavas were being ejected high in the air.

As yet there has been no lateral outbreak and no longitudinal flow. The eruption is evidently in the vast summit crater Mokuaweoweo, where Wilkes encamped, and the action has been confined to this point. We have looked for an overflow, or for a cleft in the walls of the crater for the discharge of the lavas, but none may occur. The crater is so deep and ample that the active forces of the eruption will, probably, be expended in the abyss where the fires are now raging.

During this summit eruption we have noticed Kilauea with great interest, and have had numerous reports from there. We do not get evidence of any sympathy between the two craters. Old Pele is, as usual, with no apparent increase or diminution in her activity.

We have had much thunder and lightning this winter, with tempestuous winds, hail and snow. The falls of snow upon the mountains have been frequent and beavy, extending almost to their bases.

3. American Association for the Advancement of Science.-We observe, with pleasure, that measures are in progress to revive this Associa tion after a suspension of its operations for nearly six years. An invitation has been tendered to the Association, by the citizens of Buffalo, to make that city the place of holding the first meeting after the revival; and this invitation has been accepted in behalf of the Association by its President, Dr. F. A. P. Barnard, of Columbia College, with the sanction of the Standing Committee. According to present expectation, the meeting will take place about the middle of August; but should the threatened epidemic become seriously prevalent in the country, a later date will be fixed on. When the time shall have been positively determined, circular notices will be issued to the members, by the permanent Secretary, Prof. Lovering, of Harvard University.

The Association, previous to the discontinuance of its annual meetings, proved itself a useful means of promoting a spirit of scientific inquiry in the country, and awakening a popular interest in scientific progress. The suspension of its operations, a misfortune in itself, was one of the consequences of the greater misfortune in which the whole country became involved by the attempt, now at length happily baffled, to overthrow the government. We anticipate both pleasure and profit to the votaries of science in the country from the renewal of those periodic reunions, which always brought with them a social interest superior perhaps to the scientific; and we cannot but hope that the Association may prove to some extent instrumental in healing the wounds created by civil war.

4. On Magnesia in hydraulic cements; by H. ST.CLAIRE DEVILLE.— At the session of the Paris Academy of the 4th of December last, Deville showed that magnesia, kept for some weeks in pure water sealed up so that the air is excluded, combines with water, and forms a hard and compact crystalline translucent substance, consisting of magnesia 68.3, AM. JOUR. SCI.-SECOND SERIES, VOL. XLI, No. 123.-MAY, 1866.

water 31.7, or a simple hydrate of magnesia. He has made copies of medals, like those of plaster, from magnesia thus hardened under water. Balard's magnesia, calcined at a red heat, he says, has hydraulic qualities which are manifested with a rapidity that is most admirable; though when calcined at a white heat, the property is almost wholly lost. A mixture of pulverized chalk or marble and magnesia in equal parts furnishes with water a paste which is a little plastic, but which after being some time in water affords products "of extreme solidity," and he purposes to use the mixture for making busts of artificial marble. Plaster mixed with magnesia diminishes the hydraulic properties.

On calcining dolomites rich in magnesia at a low temperature, below red heat, the powder solidifies under water very rapidly, and gives a stone of a hardness which is "really extraordinary." If calcined at a somewhat higher temperature so that a little lime is produced in the mass, the hardening still takes place, but the lime forms veins of pure aragonite in the mass, free from magnesia, the fibers of which are seen to be distinct hexagonal prisms under the microscope. When the dolomite is heated to redness, and all the lime is reduced to the state of quicklime the hydraulicity is lost. In the above results, the magnesia is the hydraulizing ingredient, it soldering together the particles of carbonate of lime exactly as in the mixture of magnesia and marble dust.

The magnesian materials obtained by Deville have been exposed for a long time to the action of sea water in the port of Boulogne by Mr. P. Michelot, and have stood perfectly the trial. Deville observes that the results explain the successful trials of Mr. Vicat from mixing magnesia with marine cements. They lead him to hope that we may thus find extensive use for a substance which, through the admirable processes of Mr. Balard, is now furnished at a very low price, and in indefinite quantities. Les Mondes, Dec. 7, 1865.

5. Meteorites of Aumale, Algeria.—A fall of meteorites took place on the 25th of August last between 11 and 12 M., in Algiers, in the district of Aumale, and 50 kilometers north of that village. The mass taken to Algiers weighed 6.8 kil., but the whole meteorite is estimated at beyond 25 kil.

On the same day and hour, a second meteorite fell in the region of the tribe of Senhadja, "fraction des Beni-Quelben," 4800 meters N. 12° E. from the place of fall of the former, in 0° 20′ E. and 36° 27′ N. This second specimen was about as large as the first, and was like it also in having approximately the form of a parallelipiped.

The meteorites consist mostly of a fine-grained ash-gray stony substance, scratching glass easily. In this base small metallic grains are disseminated, part composed of nickeliferous iron; numerous of a yellow bronze color, acting like monosulphuret of iron; some of brass-yellow possessing the characters of ordinary pyrites; black grains of chromiron in regular octahedrons with truncated edges. The specific gravity of the meteorite is 3.65. One marked peculiarity is the presence of salts soluble in water, consisting of chlorid of sodium with some carbonate of soda. The thin crust of the meteorite is dull black, slightly rugose. Within the mass there are planes, nearly flat, which are striated evidently by the friction of the two surfaces.-Ib., Feb. 15.

6. Large mass of meteoric iron.-A mass weighing 8287 lbs. (3,750 kil.) was received last year at the British Museum from Australia.-Ib., Aug. 10.

7. Remains of the Post-tertiary Mastodon or Elephant in Montana. -The "Montana Radiator" states that a large molar tooth and a tusk of an elephantine animal have recently been found in the "claim of Dr. Fales" in Last-Chance Gulch opposite the end of Broad street, seventeen feet below the surface, and four feet from the rock beneath. The tusk is 15 feet long, and 4 feet from the smaller extremity it is 27 inches in circumference; it was found 25 feet farther up the gulch than the tooth.

8. Artificial Ivory.-The best imitation of ivory-a kind now much used-is made by dissolving either caoutchouc or gutta-percha in chloroform, passing chlorine into the solution until it has acquired a slightly yellow tint, washing it well with alcohol, then adding, in fine powder, sulphate of baryta, sulphate of lime, sulphate of lead, alumina or chalk, in quantities proportioned to the density and tint desired; then hardening it, and finally subjecting it to heavy pressure. An ivory-like substance is thus made which is of great hardness and will receive a high polish.Les Mondes, Nov. 9, 1865.

9. Solution of Silk.-A solution of silk may be made by boiling it with a concentrated solution of chlorid of zinc over an excess of oxyd of the same metal, until it no longer discolors the tincture of litmus. By dialysis, the silk may be obtained again in a colorless inodorous form.Ib., Jan. 4.

10. New artificial light for photography.-Mr. Sayers, of Paris, obtains a light almost equal in power to that of magnesium, and much cheaper, from the combustion of a mixture of 24 parts of well-dried and powdered nitrate of potash with 7 of flowers of sulphur and 6 of red sulphuret of arsenic. The mixture costs only 12 cents a kilogram.-Ib., Jan. 4.

11. New test for distinguishing Cane sugar from the sugar of Grapes. -H. LEPLAY observes that the sugar of grapes blackens bichlorid of carbon, while cane sugar does not.-Ib., Dec. 14, 1865.

12. Petroleum in Archangel.—A source of petroleum has been found in Russia, in the government of Archangel, near a streamlet which runs into the river Betchora. The oil taken from it can be conveniently brought to the interior of the empire by the ordinary routes to Kama, and from there to the different regions along the Volga.-Ib., Dec. 7, 1865.

13. Petroleum of Zante.-A company has been formed for working the abundant sources of petroleum in Zante, one of the Ionian islands, sources which have been flowing, at least, for 2000 years, and which are well described by Herodotus.-Ib., Oct. 2, 1865.

14. Discovery of Stone-implements on the Island of Elba by Mr. Foresi. -Nine-tenths of the ancient implements found by Mr. Foresi on Elba are made of kinds of stone not occurring on the island, some consisting of obsidian from Naples, and others of material which has come from a greater distance. It is a question, therefore, whether they were introduced by invaders, or by commerce.-Ib., Oct. 19, 1865.

15. Polar expedition of Prussia and Austria.-This expedition leaves this spring, will first go to Spitzbergen, and make Hammerfest, the bay of which never freezes, its base of operations. On Spitzbergen it proposes to explore the coal beds noticed there more than a century since by the Dutch. It will next explore Giles land, and then pass on westwardly as far as possible toward the pole, to resolve the question of the open sea; and reaching Greenland, will explore the coast, going north

ward. Finally the expedition will turn eastward, cross in all directions the sea of Siberia, and if chances are favorable, will return by the polar seas of America. The time allotted for the expedition is eight months.

16. Geological Survey of California.-The Legislature of California has recently made an appropriation of 45,000 dollars for the continuation of the geological survey so well begun and carried forward by Prof. Whitney.

17. Copley Medal.-The Copley medal for 1865 has been given to the eminent French mathematician, Mr. Chasles.

OBITUARY.

Dr. WHEWELL died on Tuesday, March 10, at twenty minutes past five P. M., at the Lodge, Trinity College. He was born at Lancaster in 1795. His parentage was humble, and it is said that his father intended to devote him to his own handicraft, but he was sent to the free Grammar School of Lancaster, and proceeded in due course to Trinity College. His position in the Mathematical Tripos as Second Wrangler, followed by the acquisition of the Second Smith's Prize, proved the possession of the intellectual powers which he cultivated up to the day when he suffered the accident which has since proved fatal. In due time he became Fellow and Tutor in his college. In 1828 he was elected Professor of Mineralogy, succeeding Dr. Clarke. It was in connection with the British Association (of which he was President in 1841) that he drew up the "Reports on the Tides," and on the "Mathematical theories of Heat, Magnetism, and Electricity," which rank among the first of his mathematical productions. Before this he was chosen to write the "Bridgewater Treatise on Astronomy," which perhaps suggested to him the "History of the Inductive Sciences," published in 1837, followed in 1840 by the Philosophy of the Inductive Sciences," which are undoubtedly the works by which he will be best known in after years. In 1832 he resigned the Professorship of Mineralogy, but in 1838 accepted the Professorship of Moral Philosophy, which he held till 1855. In 1841, during the Ministry of Sir Robert Peel, he was nominated to the Mastership of Trinity, on the resignation of Dr. Wordsworth. As professor of Moral Philosophy he founded prizes for the encouragement of that study, which he himself always pursued with avidity. He edited Sir James Mackintosh's "Introduction to the study of Ethical Philosophy," published a couple of volumes of his own on "Morality," and among his latest productions were some translations of the "Ethical Dialogues of Plato." Besides University text-books, he published "Lectures on Political Economy," an edition of the works of Richard Jones on "Political Economy," "Architectural Notes on Churches in France and Germany," and "Some Specimens of English Hexameters," published in a book containing similar efforts by Sir John Herschel, the late Archdeacon Hare, and Mr. Lockhart.-Reader, March 10.

Mr. WILLIAM THOMAS BRANDE, D.C.L., F.R.S., the well-known chemist of the Royal Mint, died at Tunbridge Wells on Sunday, February 18th, aged eighty, being born in 1786. In 1803 he communicated several papers to Nicholson's Journal, one on guaiacum, which was read before the Royal Society. In 1808 he lectured on chemistry at Dr. Hooper's in Cork Street. Then he was connected with the Medical School in Wind