"On examining the phase-curve which had been obtained, a certain want of symmetry on the two sides of full Moon was perceived, which was ascribed to the unequal distribution of mountain and plain on the lunar surface, as was shown by a rough diagram of the lunar surface with its socalled 'seas.' It had also been found that the percentage of the Moon's heat transmitted by a sheet of glass diminished from 17.3 per cent at full Moon to about 13.3 per cent. at 2240, 11 per cent. at 45°, and 10 per cent. at 67°, distance from full Moon; a circumstance which might have been accounted for by supposing that there is a constant amount of radiant heat coming from the Moon in addition to that which, like the light, varies with the phase, had it not been found that as the Moon approached tolerably near the Sun-as for instance, on March 27, 1871, when her distance from full was 138°— -no perceptible amount of heat radiated from her surface. The less rapid decrease of the Moon's heat than of her light on going farther from full Moon, and the increase of percentage of heat transmitted by glass towards the time of full Moon, may probably be explained on the assumption that when the Sun's heat and light strike the Moon's surface the whole of the former and only a certain proportion of the latter, depending on the intrinsic reflecting power or 'Albedo' of the surface, leave it again, and consequently the shaded portions, which are inclined more towards the position of the Earth at quadrature than at full Moon, reflect a larger amount of heat as compared with the light of the former than at the latter time, and a greater flatness of the heat- than of the light- phase curve is the result. With a view of obtaining a decisive result on the question, whether or not the Moon's surface requires an appreciable time to acquire the temperatures due to the various amounts of radiant heat falling on it at different moments, simultaneous determinations of the amount of the Moon's heat and of her light were made, whenever the state of the sky allowed of it, during the eclipse of Nov. 14, 1872. The eclipse was a very partial one, only about of the Moon's diameter being in shadow; but although this circumstance, coupled with the uncertain state of the sky, rendered the observation far less satisfactory than it would otherwise have been, yet it was sufficient to show that the decline of light and heat as the penumbra came over the lunar surface and their increase after the middle of the eclipse were sensibly proportional. Both were reduced to about one half-what they were before the eclipse.”

40

The Transit of Venus in 1882.-Mr. Proctor has supplied a stereographic chart illustrative of the transit of 1882, and intended specially for comparison with the corresponding chart of the transit of 1874, supplied by him a month earlier. He remarks that it is very desirable, in considering what preparations should be made for observing the transit of 1874, to take carefully into account the relations which will be presented during the transit of 1882. "To neglect this precaution," he says, "would be as serious a mistake as for one nation to arrange its plans for either transit without a careful reference to the arrangements of other nations. It has been with the object of supplying this want that I have constructed the accompanying chart of the transit of 1882; for although the circumstances of the latter transit have been to some degree considered (by myself amongst other students of the subject), I do not think they have as yet been suffi

ciently brought into comparison with those of 1874. A comparison has indeed been instituted betwen the two transits in the 'Monthly Notices' for December 1868, wherein it is remarked that Halley's method 'fails totally for the transit of 1874, and is embarrassed in 1882 with the difficulty of finding a proper station on the almost unknown Southern continent.'. This statement, however, does not by any means accord with the results of my own investigation. On the contrary, I find that Halley's method may be said to fail totally in 1882; while, as is now well known, I find (I may even say I have demonstrated) that Halley's method is the best of all methods depending on contacts, for 1874. If we assume, in fact (which I think will be generally admitted), that no station can be regarded as suitable for Halley's method where the difference between the actual duration and the mean duration is less than half the maximum acceleration or retardation, or where the Sun is less than 10° high at ingress or egress, then absolutely no station whatever is available in 1882, unless the south pole can be approached much nearer even than it was approached by Sir Jas. C. Ross in the famous expedition when Possession Island was discovered. I confess that the prospect of successful observation at Possession Island, with a Sun only 5° high at ingress, seems to me so slight that I should hear with regret of any attempt to carry out the suggested scheme for wintering at Possession Island in 1882."

Note on Jupiter in 1873.—Mr. Knobel, who has observed this planet with one of Browning's 8-in. reflectors, remarks that this year "the most striking feature has been the great change in the equatorial zone; the port-hole markings, which were conspicuous at the previous opposition, have disappeared, and long, irregular, broken masses, horizontal and inclined at a considerable angle to the equator, have taken their place. The north temperate dark belt, which has been previously depicted as single, is really a double belt, as in the drawings. On April 20th and May 11th the south tropical dark belt appeared thinned out towards the east. The south temperate dark belt has appeared of irregular width, widening towards the west; atmospheric influences this year have been fatal to observations of colour; but on May 11th, definition being remarkably good, the south tropical dark belt was observed of a brick-red tint, more decidedly red than the darker parts of the equatorial zone." Mr. Browning remarks on the same subject: "The colour of the equatorial belt of Jupiter was fading during the last weeks of the previous opposition; during the present opposition the colour has been scarcely, if at all, perceptible; there is a conspicuous absence of any intense markings on the surface of the planet, the copper-coloured belts being fainter than usual. Great changes have taken place in the fainter markings, and some of these with great rapidity. On several occasions the belts have appeared inclined at a considerable angle to the equator. During the whole of the opposition the definition has been so uniformly bad that I have found it useless to make drawings of the planet."

BOTANY.

Mr. Hiern's Monograph of Ebenaceae.—This essay, which, however, we have not seen, we are enabled to give an account of from Professor Asa Gray's analysis of it in "Silliman's American Journal" for July. It is written by Mr. W. P. Hiern, M.A., and is published by the Cambridge Philosophical Society (vol. xii. part i.). Professor Gray says, that " In a brief account of the economical products of the order, 18 species of Diospyros, 2 of Maba, and one of Euclea, are said to supply ebony; not to speak of other hard woods, such as box-wood and pear-tree, which are artificially died black, and used in commerce as ebony; nor of the ebony of the ancients, which, according to Bertolini, was furnished by a Leguminosa. Fourteen species of Diospyros yield edible fruits. Much the best, no doubt, is that of the Japanese D. Kaki, perhaps because it has been immemorially cultivated; the next may be our N. American Persimmon, which is said to be better fit to eat after it has suffered frost. It is hardly edible without it. Characters are assigned for distinguishing D. Virginiana from the Asiatic D. Lotus ; but it is added that some specimens, of which the native country is unknown, are extremely difficult to assign with certainty. For his very full list of the numbered collections, with names assigned to the numbers, our author has earned hearty thanks. Only five genera are admitted; and one of these is a new one, of a single species, from Madagascar, Tetraclis, well marked by the valvate æstivation of the corolla. Not only are lists given of the species of each geographical region, but a complete chronological enumeration of all the published species. The treatment of the systematic part of the monograph, the Latin diagnoses and the English descriptions, and the displayed synonomy, &c., seems wholly creditable; but there is a surplus of punctuation in the diagnoses, each adjective being isolated by a comma. The fossil species are all described in an appendix, but the author disclaims responsibility for them."

Gigantic Evergreens in California.—In the "Proceedings of the Academy of Natural Science of California," Dr. Kellog says he had just returned from under the shadow of the finest evergreens that there were in Californiatrue chestnut trees, Castanea chrysophylla, from 100 to 200 feet high, 4 to 6 feet in diameter, with a clean trunk of 50 to 75 feet. Similar statements he had made times unnumbered from the Academy's first existence, and were in the "Proceedings," but seemed to be overlooked by his Eastern friends. He would also state that, on the trip, he had met with the Rhus aromatica, a shrub found in Sacramento City, on his first arrival, in 1849, and often brought to his attention since. This also had often been brought to the attention of the Academy. A Viburnum is among the Academy's collection from this part of California (Mendocino County), recently presented, besides two specimens of huckleberries, if no more.

Dr. Dawson's View as to Prototaxites.-This has been recently expressed by Dr. Dawson in the "Monthly Microscopical Journal" for August, as opposed to Mr. Carruther's doctrine. Dr. Dawson says that, in discussing affinities, he must repeat that we must bear in mind with what we have to

deal. It is not a modern plant, but a contemporary of that "prototype of gymnosperms" Aporoxylon, and similar plants of the Devonian. Further, the comparison should be not with exogens in general, or conifers in general, but with Taxinea, and especially with the more ancient types of these. Still further, it must be made with such wood partly altered by watersoakage and decay and fossilized. These necessary preliminaries to the question appear to have been altogether overlooked by Mr. Carruthers. His original determination of the probable affinities of Prototaxites, as a very elementary type of taxine-tree, was based on the habit of growth of the plant; its fibrous structure, its spirally-lined fibres, its medullary rays, its rings of growth, and its coaly bark, along with the durable character of its wood, and its mode of occurrence; and he made reference for comparison to other Devonian woods and to fossil taxine-trees.

Activity in the Growth of Plants.-A recent number of the "Gardener's Chronicle" expresses itself on this point. It says: "How little we think of the prodigious activity manifested in the growth of plants during a few weeks. The process is gradual and noiseless; moreover it is of everyday occurrence, and hence is disregarded. How much water must be absorbed and exhaled, how much air inhaled and exhaled, how much carbon fixed, during the process? Here, by way of illustration of our remarks, are some measurements of an ordinary plant of Abies Nordmanniana, which we took a day or two since. The shrub is only 2 feet 6 inches in height, the number of young shoots of this year's growth upon it is five hundred and eightyfive (585); the shoots vary in length from half an inch to 6 inches, their aggregate length is eleven hundred and seventy-one (1,171) inches, or nearly ninety-eight (98) feet. Dividing the aggregate length of the shoots (1,171 inches) by their number (585), we find the mean length of the shoots to be about 2 inches. The average number of leaves on each inch of a number of shoots taken at random was 34, so that the total number of leaves on these 585 shoots may be set down at 39,814. Assuming each leaf to be only one inch in length-which is considerably under the mark, even when all the small undeveloped leaves are taken into consideration-we should have for the leaves a length of about three thousand five hundred and one (3,501) feet, so that, in round numbers, we may say that, including the shoots and leaves, the growth in length alone of this very moderate-sized young tree, during this season, has amounted to the prodigious number of three thousand six hundred (3,600) feet, so that if the shoots and the leaves could all be placed end to end in a continuous line they would occupy considerably more than half a mile!"

Death of the Chief of American Botanists.-A late number of "Silliman's American Journal" states that "John Torrey, M.D., LL.D., died at New York on the 10th of March, 1873, in the 77th year of his age. He has long been the chief of American botanists, and was at his death the oldest, with the exception of the venerable ex-president of the American Academy (Dr. Bigelow), who entered the botanical field several years earlier, but left it to gather the highest honours and more lucrative rewards of the medical profession, about the time when Dr. Torrey determined to devote his life to scientific pursuits."

A peculiar Arrangement of Wood and Bark in the Stem of Wistaria Sinensis

has been pointed out by Mr. Thomas Meehan. The vertical section showed by the annual rings of wood that it was about twelve years old. After the eighth year's circle there was a layer of bark, and over this layer two more circles of wood. On a portion of the section another layer of bark had formed between the tenth and eleventh years' circles of wood. The bark seemed to be wholly of liber, the cellular matter and external cortical-layer of the regular bark appeared to be wanting. A longitudinal section showed where these internal layers of bark extended no further upwards, and at this point there was an evident show of wood from the interior over and down this layer of inclosed bark. He remarked that this section of wood was taken from a stem which had been led to support itself in an upright position. When the Wistaria is permitted to trail along the ground, numerous rootlets are formed along its length. He thought, from the appearance of the wood in the specimen presented, that rootlets had partially formed in these erect stems, pushing through the liber; and then, instead of penetrating entirely through the bark, and forming perfect rootlets, they remained within the cellular matter, and descending joined with the regular woody layer in forming an annular course of wood. This explanation was the more plausible, he thought, from the fact that woody stems formed on the ground. Where the rootlets went quite through into the earth, the stems were nearly regularly cylindrical; but these upright stems, on which rootlets were never seen, had an irregular fluted appearance; of course, this explanation does not accord with the formation of wood in ligneous structures as generally understood; but he could not understand how the appearance presented could have occurred in any other way than as he had supposed." Proceedings of the Philadelphia Academy of Science."

The History of the Fresh-water Algæ of North America.—“ Silliman's Journal" contains a short notice of Dr. Wood's recent work on this subject, which, as it is of interest, we give in full. It is now fully twenty years since the Smithsonian Institution performed an appropriate and most acceptable service by publishing the Nereis Boreali-Americana of the lamented Professor Harvey, thus enabling our students to study the marine Alga of our coasts. It proved to be one of the most popular of the Smithsonian Contributions to Knowledge. The institution has now enabled our students, and all who are curious in microscopic life, to enter upon the more difficult but not less interesting investigation of the fresh-water Alga, by bringing out Professor Wood's important contribution. The systematic part of this goodly volume consists of 239 pages, of imperial quarto size, in which all the United States species known to the author (exclusive of Diatomacea) are arranged and described; they are illustrated by twenty-one coloured lithographic plates, which appear to be excellent. A supplement contains six species, which are described in Professor Harvey's "Nereis," which Professor Wood did not consult in season to include in their proper places; and in the preface a fine list of fresh-water species collected by Mr. Olney in Rhode Island and named a long time ago by Professor Harvey, is reprinted from Mr. Olney's "Algae Rhodiacæ." Any student of these interesting forms may thus infer how much remains to be known of them, and all should unite in thanking Professor Wood in thus opening the way to their investigation; alsó for the elaborate bibliography appended to the