annoying indistinctness of objects observed near the horizon. In such observations as will have to be made during the coming transits of Venus, it would be of the utmost importance to get rid of this indistinctness. There would then no longer be any necessity for limiting the stations where observers should be sent to places where the sun would have a considerable elevation above the horizon. And this would be an immense advantage, because at all the stations which would otherwise be the best the sun will be low. Now the Astronomer Royal has shown that by means of a set of flint prisms, of small refracting angle, the observer can get rid in great part of the annoying dispersion we have spoken of. One prism only is used at a time, the prisms of the larger refracting angles being used for an object close to the horizon. The following reports by Mr. Carpenter (of the Greenwich Observatory) establish in the most satisfactory manner the value of the new method. 1869, July 15, 11 h. 50 m. to 12 h. 20 m. Saturn, zenithdistance about 82°, viewed with the great equatorial power 245. Atmospheric disturbances very bad:-Prism 12° corrected the dispersion perfectly; prism 8° corrected it fairly; prism 6° corrected it partially; prisms of smaller angle had no effect. 1869, July 21, 9 h. The moon, zenith-distance about 782, viewed with the altazimuth, power about 100. Prism 2 slightly diminished the colour; prism 4° better than the last; prism 6' destroyed the colour entirely. The definition of the details about the moon's ragged edge very much improved. Prisms of larger angle gave an opposite dispersion. This plan is obviously as satisfactory as it is simple. It cannot but be regarded as of extreme value and importance; and, simple as it is, will take high rank among the many important improvements which the Astronomer Royal has effected in the science of Observational Astronomy. Mr. Proctor puts forward, in a paper "On the Distribution of the Nebula," illustrated by four folio engravings, a new theory respecting the constitution of the universe. He expresses his belief that the nebulæ are not external galaxies, but that all their varieties are included within the sidereal system. In another paper he indicates a method for measuring the discs of those stars which are liable to be occulted by the moon. This method consists in causing the image of a star to rotate rapidly in a circle, which is itself rotated, but less swiftly. Thus the image of a star follows an epicycloidal path, many coils of which will be visible simultaneously, owing to the persistence of luminous impressions. When the moon occults a star (a process which in reality occupies but a small fraction of a second) the coils will vanish, but according to the greater or less duration of the occultation a larger or smaller arc of the coil last formed will exhibit a gradual fading-off of light towards its extremity. Mr. Proctor has calculated that a star ten times as far off as a Centauri, and having a real diameter as large as our sun's, would give an arc of fading light about 56 degrees in length. 4. BOTANY. Edible Fungi.-During the last few years great attention has been paid by botanists on the one hand, and epicures on the other, to the edible qualities of certain fungi. Notwithstanding the prejudice generally entertained against this class of vegetable productions, extending in Scotland, Wales, and some parts of England even to the common mushroom, there is no question that a considerable number of species, very abundant in this country, are not only wholesome, but delicious articles of diet, and are at least as easily distinguished, with a little practice, from the poisonous or suspicious species, as berries or other wild fruits. Containing a larger proportion of nitrogen than any other family of the vegetable kingdom, they furnish an abundant supply of nourishment at a period of the year when very little else is to be obtained. It is calculated that there is scarcely a parish in England where tons of wholesome food are not allowed to waste every year, to say nothing of the facilities for their artificial culture. Mr. Berkeley reckons that there are at least 30 distinct English edible fungi; Dr. Curtis has partaken of 40 in North Carolina, and enumerates 111 species in that state alone reputed to be edible. Fries, the greatest living cryptogamist, is publishing a large work on the edible and poisonous fungi of Sweden; several works of a similar character have recently been brought out in Italy; in our own country the Rev. M. J. Berkeley, Mr. Worthington G. Smith, and Dr. Bull of Hereford, may be mentioned as having paid special attention to the subject. In addition to the mushroom Agaricus campestris and the truffle Tuber æstivum, the following species are wholesome, pleasant to the taste when cooked, easily distinguished from all other species, and more or less abundant in different parts of the country:-Agaricus arvensis, or the horse-mushroom; A. procerus, the parasol-mushroom; A. ostreatus, the vegetable oyster, growing on the trunks of trees; A. melleus, abundant on dead stumps; A. orcella, the vegetable sweet-bread; A. prunulus, the plum-mushroom; Morchella esculenta, the morel; Hydnum repandum, the hedge-hog; Fistulina hepatica, the vegetable beef-steak, on the stumps of hollow trees; Coprinus comatus, very common in gardens; Marasmius oreades, the fairy-ring champignon; Boletus edulis, in woods; and Lycoperdon giganteum, the giant puff-ball, when in the young state. Many of these species are favourite articles of food in the autumn and winter with the peasantry in various parts of the Continent, and are everywhere sold in the markets. Our common mushroom is among the kinds forbidden by the police regulations to be sold in Rome, but is to be met with in the markets of Palermo and Messina. Acclimatization of Half-hardy Plants.-Great efforts have recently been made in France to naturalize trees and shrubs-natives of warmer climates; and these have been attended with considerable success in some instances. The Bamboo, introduced at Tours, Macon, and Angers, has succeeded admirably, and has withstood a very considerable degree of frost. It seems likely to flourish even in the climate of Paris, where it is grown in the gardens of the Société d'Acclimatation. Several species of Eucalyptus, especially the E. globulus, have also been planted extensively in the Department of the Var, where they have been found to resist the destructive northwest wind known as the mistral. The Fertilization of Winter-flowering Plants.—Mr. A. W. Bennett contributes to the first number of the new scientific magazine, 'Nature,' the results of some observations on the fertilization of those plants which habitually flower in the winter, when there are few or no insects to assist in the distribution of the pollen. He finds that in those wild plants which flower and produce seedbearing capsules throughout the year, as the white and red deadnettles, shepherd's purse, chickweed, groundsel, &c., the pollen is uniformly discharged in the bud before the flower opens. Many garden-plants, on the other hand, natives of warmer countries, but which still flower with us in the depth of winter, never bear fruit in this climate, and in them the pollen is not discharged till the flower is fully open. Of this class are the yellow jasmine and the Cheimonanthus fragrans, or all-spice tree; in the latter species the arrangement of the pistil and the stamens is such as to render selffertilization impossible. Leonardo da Vinci as a Botanist.-In the recently commenced Nuovo Giornale botanico Italiano,' published at Florence, Signor Uzielli has an interesting article on some botanical observations of Leonardo da Vinci, showing that to the great painter is due the credit of the first observation of certain points in the structure of plants, which has been generally attributed to writers of a considerably later date. The constancy of a uniform arrangement of the leaves on the branches in the same species, known as the Law of Phyllotaxis, is stated in botanical works to have been first observed by Grew and Malpighi towards the close of the seventeenth century. Da Vinci, however, who lived from 1452 to 1519, records observations to the same effect, though not so accurate, in his great "Treatise on Painting.' To the same two botanists is also ascribed the discovery of the mode in which the stems of exogenous trees increase beneath the bark by the formation of concentric rings of wood, from the number of which the age of the tree can be determined. This had, however, also been already observed by Da Vinci, and is recorded in passages in the same work. Arctic Flora.-Dr. Berthold Seemann discusses in the Journal of Botany' the question whether vegetation extends to the North Pole, supposing land exists there. He answers the question in the affirmative, maintaining that excessive cold in winter exercises but a limited influence upon a vegetation which, like the Arctic, enjoys the protection of a thick covering of snow, and is besides in a state of inactivity. The temperature of the summer during the months of July and August has by far the greatest share in the distribution of vegetable life in the northern regions; and the lowest temperature during those months is not found in the most northerly point yet reached by any exploring expedition, but in Winter Island on the eastern shores of the Melville Peninsula, where the mean temperature during July and August ranges between 34° and 36° F. That spot, which may be called the phytological pole, is nevertheless covered with vegetation; and, knowing as we do, that plants do grow not only on a frozen soil, but even, as in Kotzebue Sound, on the tops of icebergs, there is no reason to suppose that the terrestrial pole is destitute of vegetation. The most northerly berry-bearing plant yet recorded is Vaccinium Vitis-Idea, or the cranberry, gathered in Bushman Island, on the north-west shore of Greenland, by Captain W. Penny, or in latitude 76° N., longitude 66° W. The most northerly berry-bearing genera are Vaccinium, Oxycoccus, Rubus, Cornus, and Empetrum. It is stated that occasionally berries ripen in Lapland. Vegetation of Howe's Island.-The flora of this island, 300 miles from Sydney and 500 from Norfolk Island, has been investigated by Mr. Charles Moore, and is found to resemble much more closely that of the latter island than of Australia. Its situation is 31° 36′ S. lat., 159° 5' E. long.; it is 4 miles in length and 1 in breadth, possesses two mountains about 2500 feet high, and is entirely covered with vegetation, with no barren spots except the coast and the precipitous cliffs. The indigenous species are very few, most of them being peculiar to the island and undescribed. Of Endogens there are four species of Palm, all undescribed and of great value to the natives; two species of Pandanus; three Grasses; two Orchids; a Juncus; a Smilax; one species belonging to Iridaces, one to Amaryllidaces, three to Cyperaces, and one to Commelynaces. All the clearings are, however, covered with introduced European plants, including the couch-grass. Among Exogens, the Australian Proteace and Leguminosæ are entirely wanting; Epacrida and Myrtacea, so abundant in Australia, are represented, the former by a single species, a tree 30 or 40 feet in height, grow ing at great elevations; the latter by two, the leaves of one of which are used by the natives in the place of tea; a very remarkable undescribed Ficus forms a considerable portion of the larger vegetation, growing sometimes 100 yards across, with very numerous root-stems. The castor-oil plant and Solanum laciniatum are among the most troublesome introduced weeds. Ferns are very abundant, but of non-Australian types; the genera Adiantum and Aspidium, so abundant in Australia, New Zealand, and Norfolk Island, were not observed. The Lichens of Greenland.-Dr. Lauder Lindsay has worked out with great care, in an article read before the Botanical Society of Edinburgh, an account of all that is at present known respecting the Lichens of Greenland. While in 1840 only 59 species had been recorded, Dr. Lindsay is now able to enumerate 268 as natives of Greenland, and thinks that this number may probably be raised to 300. The degrees of latitude within which they have been collected range from 60° to 75°, the majority having come from about 70°, a few from as far north as 82°. The almost entire absence of arboreal vegetation in Greenland necessarily affects the character of the Lichen-flora, very few corticole and foliaceous species being found, but a great preponderance of the saxicole forms. One prominent feature is the great abundance of the sombre-coloured Umbilicaria, giving in many parts a funereal colouring to the landscape. Deducting the species that are mainly or entirely confined in their distribution either to Greenland or to Arctic countries, the majority at least of the remainder occur on the Scandinavian Alps, and many of them on the Alps of Scotland and Switzerland, or generally on those of continental Europe; while a considerable number are common British forms. The lichen-flora of Greenland differs, on the other hand, very considerably from that of Arctic America. The lichens of Spitzbergen and its islets are as numerous as those of Greenland, notwithstanding the smaller area; while the whole list of Melville Island lichens contains only twelve species. There is no record of any species of lichen being turned by the Greenlanders to any economic purpose, notwithstanding the abundance of Cladonia rangiferina, or the "Reindeer-moss," and of other species which, in other Arctic countries, have been serviceable in supplying the wants of man or animals. Hibernation of Duck-weed.-It has long been known that some species of Lemna, or duck-weed, produce, at the approach of winter, leaves of a different character to those formed in the spring, which fall to the bottom of the pond or stream, enabling the plant to live through the winter. A series of more accurate observations on this point is recorded by M. Van Horen in the Bulletin de la Société Royale de Botanique de Belgique.' The species of Lemna indigenous to Belgium are the same as those found in this country; of these |