IT is stated in Nature that the annual meeting of the Association of Public School Science Masters was held at the London Day Training College on December 31, 1918, and January 1, 1919, under the presidency of Sir Ronald Ross. The subject of the president's address was "Observations on the results of our system of education." A lecture on poisongas warfare was given by Lieutenant-Colonel Smithells. There were discussions on the impartance of restricting specialization in university scholarship examinations and giving weight to general education, opened by Mr. F. S. Young; science in the general education of boys, opened by Mr. W. D. Eggar and Mr. C. V. G. Civil; and courses in general science for classical Sixth Forms, opened by the Rev. S. A. McDowall. UNIVERSITY AND EDUCATIONAL GIFTS aggregating $128,000 to Yale University were announced on January 23. They include $25,000 to the Forestry School from Mr. and Mrs. Gifford Pinchot. THE Zoology department of Wabash College, of which Professor A. Richards has charge, has received from the estate of Professor Donaldson Bodine, formerly professor of zoology the sum of $5,000, to provide for the purchase of books for the zoology department, subject to an annuity. Ar the request of Professor Bailey Willis, professor of geology at Stanford University, who is continuing his war work with the House Commission in New York, Professor James Perrin Smith will act as executive head of the department of geology and mining for the coming year. Dr. Eliot Blackwelder, of the University of Illinois, has been appointed acting professor of geology during the winter quarter. MR. H. P. STUCKEY, for the past ten years horticulturist at the Georgia Experiment Station, has been appointed director, to succeed J. D. Price, who resigned to accept the position on the Railroad Commission to which he was elected. Other changes in the station staff are the appointment of Mr. T. E. Keitt, formerly chemist of the South Carolina Sta tion, as chemist the appointment of Mr. H. E. Shiver, formerly assistant in chemistry at the South Carolina Station as assistant chemist; the appointment of J. A. McClintock, formerly extension pathologist for Georgia, as plant pathologist and botanist, and the resignation of Mr. J. C. Temple, bacteriologist. DR. N. L. BOWEN, of the Geophysical Laboratory, Carnegie Institution, has been appointed to the professorship of mineralogy at Queen's University, Kingston, Ontario. DISCUSSION AND CORRESPONDENCE AN UNCOMMON ICE FORMATION WHILE skating on the upper part of the Charles River at North Bellingham, Mass., January 13, 1918, during a severe cold spell, we encountered an ice formation of a kind wholly new to us, though we have practised river skating for many years and are both fairly observant of natural phenomena. There is a low dam here over which a good head of water was flowing. Just below the dam an uneven bridge of ice resting partly on rocks and, partly on the water formed a hood over the stream, and out of this rose a considerable number of upright columns of ice superficially somewhat resembling stalagmites. They were of pretty uniform diameter, about four or five inches, and varied in height from two or three inches to as many feet, while the tallest was perhaps three and a half feet. This tallest one and a number of the others were completed, being finished off with a tapering cap of snow-like structure that curved over towards the dam and into the wind, which was blowing pretty strongly down stream. Many, however, in process of formation showed how they were made. They were all tubular and were built up from the inside by the bursting of bubbles that rose through the tubes and the freezing of the resulting spray. It was evident that the rush of water over the dam carried air with it under the hood of ice below, and that this air found vent here and there in the form of bubbles, which, bursting, gradually built up these vertical columns. Each unfinished, or live, column showed a crown of bursting bubbles. The formation of the caps that finished off the completed, or dead, columns is, perhaps, to be explained in this way: When the column rose to a point where the wind reached it above the lee of the dam, the spray from the bursting bubbles would lodge chiefly on the leeward, or downstream, side of the orifice and in freezing would build up that side faster than the upstream side. The top would thus curve over upstream, the freezing spray building not only upwards but back against the wind, just as the hoar-frost or frozen mist of mountain-tops builds against a high wind. This would, of course, close the orifice in time and put a stop to the growth of the column. It is not entirely clear how the bubbles rise to so considerable a height in the tubeswhether they are forced up by the rush of water over the dam and under the hood of ice, or whether it is because the air they contain is heated by the water to a higher temperature than the surrounding air. On this point, as on the whole subject, we should be very glad to get the opinions and observations of any one else who has seen this formation. Inquiry among friends has failed as yet to bring to light any similar observations on the part of others, and we find no mention of this phenomenon in the fourteen volumes of Thoreau's "Journal," observant as he was of the forms taken by ice, snow and frost along the Concord River and its tributaries. This has made our observation seem worth recording, though we can not doubt that under similar circumstances it might be repeated any cold winter. FREDERICK A. LOVEJOY, WEST ROXBURY, MASS. CELLULOID LANTERN SLIDES TO THE EDITOR OF SCIENCE: In a recent letter to SCIENCE regarding celluloid lantern slides, Mr. A. W. Gray states that "tracing cloth and waxed paper are usable; although their limited transparency produces a rather dark field, and the texture of the material shows plainly." The writer experimented some time ago with substitutes for glass lantern slides, giving special attention to slides which could be prepared quickly for temporary use. I found that a satisfactory slide could be made by drawing figures or diagrams on thin white paper with india or colored ink. After the ink had become thoroughly dry both sides of the paper were brushed over with a lightcolored penetrating oil. The thin glazed white paper used for duplicating typewritten letters serves admirably for the paper and a light neatsfoot makes a satisfactory oil. These paper slides may be inserted in cardboard holders and with suitable projecting apparatus the results are all that could be desired. The effect of the oil is to increase greatly the transparency of the paper and when new the texture of the paper is quite imperceptible. Figures of lesser sharpness can be made with a fountain pen or even with a pencil. Diagrams and pictures of appropriate size may be cut from magazines or bulletins and treated with oil as outlined above. These are more satisfactory, of course, if no printing appears on the back, but for temporary use the printing in many cases will not destroy the usefulness of a diagram. I have also made good slides in the same manner by treating 3 X4 photographic prints with oil. The projected pictures, while less bright than those procured with glass plates, present a softer effect and are especially interesting in the case of portraits. Since the usual photographic paper is quite heavy the lantern must be placed nearer the screen but if thinner paper could be obtained the results would be quite satisfactory if the usual distance were maintained. DEPARTMENT OF PHYSICS, KENYON COLLEGE RALPH G. HUDSON HOLDING LARGE SPECIMENS FOR DISSECTION IN the zoological laboratory there are many things which are valuable aids in time and convenience. In dissecting large specimens it is often necessary to have some method of holding parts of the anatomy away so as to allow freer rein to one's actions, or of holding the specimens open firmly. This may be done by using trays of galvanized iron with four or more loops of metal soldered on the sides to which ordinary heavy rubber bands are attached. To these rubber bands are tied small fishhooks which have had their barbs filed off. These hooks are to be fastened to any part of the anatomy so as to hold the specimen firmly, or to pull certain parts to the desired position. If a plain tray without the side loops is used, the rubber bands may be fastened to the ends of strong strips of cloth. The cloth is placed under the tray, one piece at the top and the other at the bottom, and if the strips are of the proper length, the rubber bands and hooks will be in relatively the same position as when they are fastened to rings along the edge of the pans. Removing the barb allows the hook to be withdrawn at any time without injuring the specimen. Care should be used not to stick the hooks in the hand, for owing to the strength of the rubber bands, the hook would make an ugly wound should it slip. The advantages of this method are the saving of time and the lack of trouble, for we have a self-adjusting holder, as the rubber band allows for any change to be made in the position of the specimen or any of its parts. As compared to the old methods, it neither incurs the expense and the time of adjusting, as is the case with chains and hooks, nor the unreliability and unsteadiness as in the case where string and bent pins are used for this purpose. JOHN M. LONG WASHBURN COLLEGE SCIENTIFIC BOOKS Papers from the Department of Marine Biology of the Carnegie Institution of Washington. Vol. 9, pp. iii +362, 105 pls., 14 figs., 1918. In this handsome and very important volume there is a great deal of information that is of the highest value to the biologist, geologist, paleontologist and oceanographer. In fact, there is so much of value that this notice can mention but a few of the results that are most interesting to the reviewer. There are eleven papers, of which the largest is by T. W. Vaughan on "Some Shoal- water Corals from Murray Island (Australia), Cocos-Keeling Islands, and Fanning Island" (185 pp. and 73 pls.). The other authors are Alfred G. Mayer, M. I. Goldman, Albert Mann, Joseph A. Cushman, M. A. Howe, R. B. Dole and A. A. Chambers, R. C. Wells and L. R. Cary. The shoal-water corals of the Great Barrier Reef of Australia described by Vaughan in the systematic part of his paper, amount to 149 forms and 38 genera, 1 genus and 15 species being new. Certain species range from the east coast of Africa on the west to the Hawaiian and Fanning islands on the east. Great pains have been taken not only to determine the proper names, but to give ecologic conditions as well. The illustrations are the finest we have ever seen of the skeleton of corals, and as the photographs are not retouched, the heliotypes look as natural as the corals themselves. Many of Dana's types are figured. The ecology of the Murray Island corals near the northern end of the Great Barrier Reef is described at length in the first paper by Mayer, which is a very important one. More than forty species were studied, with a view to determine the factors of their distribution. These factors, in the order of their importance, are: temperature, silt, the effects of moving water, and the struggle for existence between the species. All corals appear to be Whenever the water is wholly carnivorous. agitated, cool and free from silt, the reef-flat is wide and covered with an abundance of living corals, but where the water is calm, hot and depositing silt faster than the corals can remove it from themselves, the reef-flat is narrow and the corals deficient. Much silt kills corals in about two days. In a square 50 feet on a side, there occurred two living corals from 375 to 425 feet from shore, while in the same area, at from 1,400 to 1,500 feet out from land, there were 1,833 heads. Four genera constitute 91 per cent. of the corals present. In regard to annual rate of growth among the stony corals there are some interesting facts. Some of the identical coral heads of Thursday Island measured and photographed by Saville-Kent were remeasured by Mayer twenty-three years later. These results show that large coral heads may increase as much as two inches in diameter per year, while some kinds do not grow beyond a certain specific size. The average annual growth appears to be about one inch, though in the Floridian reefs the rate of increase is less. Mayer states that stream waters pouring outward from forested volcanic shores are alkaline and thus can not dissolve limestone by reason of their "acidity." Thus the MurrayAgassiz solution theory of the formation of atolls is not supported. Holothurians are a potent factor in dissolving the materials that go to make reef limestones, which they swallow, and the effects of currents in scouring are important factors tending to convert fringing reefs into barrier reefs. The problem of the precipitation of CaCO, in the ocean and the possibility of its solution there is discussed in the light of the latest evidence, and the conclusion is reached that in the shoal waters of the tropics, ocean-water does not dissolve calcium carbonate, but that the contrary process-precipitation by both inorganic and organic (bacterial) agencies-is taking place. Conditions in the deep sea, and perhaps in the cold waters of high latitudes, are different. In the Murray Island reef sediments, Vaughan states that the dominant rock makers are (1) corals (34 to 42 per cent.); (2) coralline alga (32 to 42 per cent.); (3) molluscs (10 to 15 per cent.); foraminifers (4 to 12 per cent.) and alcyonarians. Other marine animals are unimportant in their skeletal additions. Cary shows that, in the Tortugas area, the gorgonians are also very important reef builders and therefore great rock contributors, since nearly 20 to 36 per cent. of their bodies consists of calcareous spicules. As almost all of these colonies die a violent death, and on the average all those living within 30 feet of water are replaced in five years by other colonies, he calculates that at least one ton of spicules or limestone is added per year to each acre of reef ground. In fact, when the gorgonians are common, they are more important as limestone makers than are even the stony corals. CHARLES SCHUCHERT SPECIAL ARTICLES A METHOD OF DEMONSTRATING THE DIFFERENCE-TONES Ir a Rayleigh inductometer bridge be connected up, and a telephone receiver A be in series with the alternating e.m.f., the demonstration of the difference-tone is an exceedingly simple matter. Let the bridge be balanced for a high frequency F', say about 2,500; this tone will therefore not reach the ears if the balancing receivers be of the double, head-strap variety. Now whistle a scale into the receiver A. Since the bridge is not balanced for the new frequency, the whistle "gets through" into the balancing receivers. But one also hears another tone which slides down as the whistle slides up the scale. If between the balancing receiver and the bridge a good amplifier be connected, then the balancing receiver may be a "loud-speaking receiver " (such as are now used for announcing trains in large stations, etc.) and the apparatus is suitable for class demonstration. The great advantage of this arrangement is that we are not confined to any two fundamentals, as in the case of forks. The phenomenon is unquestionably slightly complicated by the action of one alternator on the other, but I had not the time to see to what extent the extra tone differs from F"-F". The writer offers the above as a lecture experiment in physics and psychology, being under the impression that it has not been reported before. PAUL F. GAEHR WELLS COLLEGE, AURORA, N. Y. THE AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE REPORT OF THE TREASURER FOR 1918 IN conformity with Article 15 of the constitution and by direction of the council, the treasurer has the honor to submit the following report for the period December 15, 1917, to December 16, 1918, both inclusive. |