March 25, 1909] 



NA TURE 



107 



obvious relationship to the contour lines, but it is by no 

 means a constant one, owing to the positions of the moun- 

 tains and the local air currents. The wettest parts include 

 the portion of the Carnarvon mountains within a radius 

 of about two miles from the centre of Snowdon, in which 

 area the average fall is more than 150 inches per annum ; 

 at Glaslyn, on the lee side of the summit, and within the 

 Snowdon crater, the mean rainfall is apparently 197 inches. 

 An area of about 167 square miles on these mountains has 

 a rainfall of more than 100 inches per annum. In South 

 Wales, at the Bwlch Pass, the mean is about 130 inches. 

 Over the whole country, the fifteen years 1872-86 had an 

 average annual fall of 110-14 per cent., and the fifteen 

 years 1887-1901 had 91-44 per cent., of the mean. Many 

 localities are still poorly provided with rain-gauges ; no 

 record appears to be kept on Cader Idris. 



The Electrical Review for March 5 devotes three pages 

 to reports of the discussions at London, Manchester, and 

 Dublin of the paper on the use of large gas engines for 

 the generation of power, read last month before the 

 Institution of Electrical Engineers by Messrs. L. Andrew 

 and R. Porter. In a leading article on the subject it 

 points out how little has been done in this country to 

 make gas engines of more than 1000 horse-power a success, 

 and attributes this state of affairs to a tendency of our 

 fellow-countrymen to leave- other countries to do the 

 pioneering work, and -to hope to take up the subject when 

 the main difficulties have been overcome. In its condemna- 

 tion of this practice the Electrical Review has our cordial 

 support. 



P.VRTS viii., ix., and x. of vol. xliv. of the Proceedings 

 of the .American Academy of Arts and Sciences consist of 

 papers by Mr. P. W. Bridgman, of the Jefferson Physical 

 Laboratory of Harvard University, dealing with high 

 hydrostatic pressures. The first describes a primary 

 mercury gauge in which the pressure of the mercury on a 

 piston, kept in rotation to minimise friction effects, is 

 balanced by weights. By means of this gauge pressures 

 up to 7000 kilos, per square cm. may be determined to an 

 accuracy of one-tenth per cent. The second describes a 

 gauge in which the change of the electrical resistance of 

 mercury under pressure is utilised to determine the pressure. 

 The author finds that at 7000 kilos, per square cm. the 

 resistivity of mercury is reduced to 0-83 of its value at 

 atmospheric pressure. In the third paper the apparatus 

 used in the measurement of the compressibilities of certain 

 solids and liquids is described. For solids, a bar of the 

 material is enclosed in a strong cylinder of steel, and is 

 pressed against one end of the cylinder by a spring. The 

 other end of the bar carries a brass ring which is in 

 contact with a shoulder in the cylinder. When the bar 

 is compressed the ring is forced along it, and the extent 

 of the motion gives the difference between the changes of 

 length of bar and cylinder. The latter is measured by 

 microscopes outside the cylinder. In this manner the 

 compressibilities of steej, aluminium, and glass have been 

 determined by Mr. Bridgman. 



A P.4PER on hydroplanes, or skimmers, was read by Sir 

 John I. Thornycroft, F.R.S., at the Model Yacht Club ori 

 March 4. Any vessel which greatly reduces its displace- 

 ment at high speeds is generally called a hydroplane, but 

 as the gliding surfaces are not always plane, skimmer is a 

 more appropriate term. Steady gliding on the surface of 

 water is difficult to secure ; this may probably be obtained 

 by the use of a number of planes, but at the expense of 

 more power. Mr. Froude was of opinion that a single 

 plane was best, but this must maintain a particular angle 

 NO. 2056, VOL. 80] 



to the water surface. In a boat intended for skimming 

 there are a number of elements to be considered, which, 

 unfortunately, do not all lead to the same proportions of 

 design. The lifting force depends on the amount of surface 

 and the speed, while the friction for a certain amount of 

 surface decreases with the length. Again, the speed at 

 which skimming will commence increases with the length ; 

 naturally this limit should be kept as low as possible. 

 Below a certain velocity the formation of large waves 

 causes bad performance in skimmer models ; this difficulty 

 may be lessened by extending the amount of supporting 

 surface or by reducing the weight of the vessel, the surface 

 remaining the same. A boat very wide and short in shape 

 leads to excessive air resistance — an important factor at 

 speeds of thirty miles per hour. The author gives the 

 results of much of his experience witli models. The com- 

 plete paper, together with the lines and a photograph of 

 the successful motor-boat Gyrinus at full speed, the latter, 

 built by the author's firm, having won the International 

 Race for 8-metre boats last year, will be found in 

 Engineering for March 12. 



In the issue of N.^ture for February 11 last (vol. Ixxix., 

 p. 43S) a note was published dealing with the general 

 report on the operations of the Survey of India administered 

 under the Government of India during 1906-7. A remark 

 in the note concerning the pendulum experiments carried 

 out states that " the results obtained have been found to 

 agree with those obtained by Prof. Hecker in 1905." 

 .Major Lenox Conyngham points out to us that this remark 

 is calculated to give the impression that the Survey of 

 India had merely been going over ground already traversed 

 by Prof. Hecker, whereas the reverse was the case. The 

 words of the report are : — " The results of Prof. Dr. 

 Hecker 's observations at Jalpaiguri in 1905 have been 

 received and found to agree perfectly with those of Major 

 Lenox Conyngham." 



It will be remembered that the centenary of the Geo- 

 logical Society of London was celebrated in 1907. Articles 

 dealing with the celebration proceedings appeared in the 

 issues of Nature for August i and October 3, 1907 (vol. 

 Ix.wi., pp. 317 and 569). Messrs. Longmans, Green and 

 Co. have now published for the Geological Society a de- 

 tailed account of the varied meetings, held from September 

 26 to October 3, 1907, in honour of the occasion. The 

 volijme, which runs to 166 pp., and costs 2S., has been 

 compiled by the senior secretary of the society, Prof. W. W. 

 Watts, F.R.S., and includes an exhaustive account of the 

 excursions, the reception, the congratulatory letters and 

 addresses, the presidential address, the social functions, and 

 the visits of the guests of the society to the Universities 

 of O.xford and Cambridge. An excellent portrait of Sir 

 Archibald Geikie, K.C.B., president of the Royal Society, 

 forms the frontispiece to what is in every way an interest 

 ing memorial of an important celebration. 



A FIFTH edition of the late Mr. Catchpool's " Text-book 

 of Sound " has been published by Mr. W. B. Clive. The 

 work has been revised and enlarged by Mr. John Satterly. 

 The revision has consisted more of additions than of altera- 

 tions, and these include many instructive experiments, with 

 descriptions of apparatus and manipulation. 



.Among the forthcoming publications of the Society for 

 Promoting Christian Knowledge are : — " The Spectroscope 

 and its Work," by Prof. H. F. Newall, F.R.S., and 

 " English Wild Flowers," by Prof. Henslow, with more 

 than 200 coloured illustrations of plants, natural size, 

 drawn by G. Layton. 



