LONDON winters are more remarkable for dismal drizzling rain and impenetrable fog than for snow and ice; but about half a dozen times in the last three hundred years truly arctic conditions have prevailed in that metropolis, and the River Thames has been frozen over so firmly that men and horses could go upon it. Each of these periods has been the occasion of a “frost fair"; booths have been erected on the ice; printing presses set up, various sports and games indulged in; and the whole population has joined in celebrating the rare event. The first great frost fair was held in January, 1608; but the most famous of all was that of 1683-4, which lasted from the beginning of December to the 5th of February. Evelyn gives the following description of this fair in his “Diary": “The frost continuing more and more severe, the Thames before London was still planted with boothes in formal streetes, all sorts of trades and shops furnish'd and full of commodities, even to a printing presse, where the people and ladyes tooke a fancy to have their names printed, and the day and yeare set down when printed on the Thames: this humour tooke so universally, that 'twas estimated the printer gain'd £5 a day, for printing a line onely, at sixpence a name, besides what he got by ballads, etc. 'Coaches plied from Westminster to the Temple, and from several other staires, to and fro, as in the streetes, sleds sliding on skeetes, a bull-baiting, horse and coach races, puppet-plays, and interludes, cookes, tipling, so that it seem'd to be a bacchanalian triumph, or carnival on the water.” King Charles II. and his family visited the fair, and had their names printed on a quarto sheet of Dutch paper, which is still extant. During the frost fair of January, 1716, .it is recorded that an uncommonly high spring tide, which overflowed cellars on the banks of the river, raised the ice fully fourteen feet, without interrupting the people in their pursuits. Similar fairs were held in 1740, 1788-9, and 1814. The last was one of the gayest and most animated of these events, though .it lasted only four days. THE sixty-third meeting of the American Association for the Advancement of Science will be held in Washington, December 27th to 30th, 1911, under the presidency of Prof. Charles E. Bessey, of the University of Nebraska. In conjunction therewith will be held the tenth of the “convocation week” meetings of affiliated societies, viz.: American Anthropological Association, Astronomical and Astrophysical Society of America, Society of American Bacteriologists, American Society of Biological Chemists, Botanical Society of America, American Chemical Society, American Civic Alliance, American Economic Association, American Association of Economic Entomologists, Entomological Society of America, American Fern Society, American Folk-Lore Society, Association of American Geographers, Geological Society of America, American Federation of Teachers of the Mathematical and the Natural Sciences, American Home Economics Association, Society for Horticultural Science, American Association for Labor Legislation, American Microscopical Society, American Nature-Study Society, Paleon-tological Society of America, American Physical Society, American Physiological Society, American Phy-topathological Society, American Psychological Association, Sigma Xi, American Sociological Association, The magnet is mounted on a cast iron pillar, in such a manner that it can easily be turned in any direction. The pillar is hollow and is provided with castors, so that the apparatus can be moved without difficulty. The axis of the magnet is about four feet above the floor. At a little more than half this height a shelf is attached to the pillar for the purpose of supporting the patient's arms and keeping his head motionless during the operation. The base of the pillar contains the electric switch which is closed by depressing a pedal and is thrown open by a spring the instant the foot is raised. A special device protects the contacts from injurious sparking. The current-density in the coil is very small ill comparison with its density in other electromagnets. Hence very little heat is developed—a condition essential to permanent efficiency. In tractive power Haab's electromagnet stands at the head of all known electromagnets used by oculists. At a distance of 1.2 inches, for example, it exerts a pull more than twice as strong as that of the largest Volkmann magnet. The electromagnet is designed for use on direct current circuits of 60 to 300 volts, but it can be employed on alternating uniphase or triphase circuits, with the aid of a suitable transformer. The maximum power required is about one kilowatt. The total weight of the apparatus is about 286 pounds. This apparatus, although designed primarily for the use of oculists, is admirably well adapted for the extraction of iron filings and splinters, hammer-scale, etc., from wounds in any part of the body. Hence it may advantageously be installed in the hospital rooms of all large mining and metallurgical establishments. Experience shows that the magnets now employed in these rooms are used as often on hands and arms as on eyes. Wounds incurred in planing iron are often filled with fine splinters of iron. The removal of these splinters singly with pincers or needles is a tedious and painful operation, but all of the iron or steel particles can be extracted quickly by means of a powerful magnet. A Seismograph in a Coal Mine NATURE states that a seismograph has recently been installed in the Tunnel Colliery, at Nuneaton, for the purpose of ascertaining whether the apparently inexplicable falls of coal and roof in mines have any relation with the occurrence. of earthquakes. Aside from the practical object in view, a comparison between the records of this instrument and those of instruments on the surface is likely to be of much scientific interest. American Statistical Association, Sullivant Moss Society, Southern Society for Philosophy and Psychology. The administrative headquarters of the meeting will be at the New Willard Hotel, where all members will register, beginning at 9 o'clock, December 27th. The opening general session of the Association will be held at the U. S. National Museum at 8 P. M., December 27th. It is expected that an address of welcome will be given by the President of the United States, and the retiring president of the Association, Dr. A. A. Michaelson, will give his annual address, the subject being “Recent Progress in Spectroscopic Methods.” The various sectional meetings begin at 10 A. M., December 27th. The programme of entertainments in. cludes an exhibition cavalry drill at Ft. Myer, on the afternoon of December 28th, and an informal reception at the Corcoran Art Gallery the same evening. The Australian Antarctic Expedition DR. MAWSON'S projected antarctic expedition has secured a suitable vessel—the “Aurora,” built at Dundee in 1876—and the preparations are proceeding rapidly. As we have previously stated, the object of this -expedition is the thorough exploration of a portion of Antarctica, rather than a dash for the pole. It is announced that an aeroplane forms part of the equipment. The Scientific American-Gould Prize ACOPY of the rules governing the competition for the flying machine prize of $15,000 offered by Mr. Edwin Gould under the auspices of the Scientific American will be found in the current issue of the Scientific American Supplement.