358 



NA TURE 



[August 13, 1908 



it is assumed tiiat the curvature of the isobars is identical 

 witli the curvature of the path. This is only true in the 

 special case when the pressure distribution remains con- 

 stant. If the curvature is small or the pressure distribution 

 is changing rapidly, the difference between the curvature 

 of the isobars and that of the path may be considerable, and 

 the gradient velocity obtained by assuming them identical 

 may be considerably in error. Unfortunately, the deter- 

 mination of the wind path is impossible under these 

 special conditions, and the method of determining the 

 gradient velocity then becomes untrustworthy. Mr. Gold 

 optimistically extricates himself from the difficulty by 

 suggesting a method for determining the motion of the 

 centre of curvature from the difference between the observed 

 velocities and the velocities calculated from the curvature 

 of the isobars and the distance between them. 



Two theoretical results arrived at by Mr. Gold are of 

 special interest. He has calculated the time required for 

 air, starting from rest, to acquire the gradient velocity 

 and to adjust its motion to the direction of the isobars. 

 The values found for latitude 50° vary between 4 hours and 

 16 hours for different conditions of motion, and are 

 thus small compared with an interval such as the dav. 

 On another page he gives us an interesting counterpart 

 to the well-known fact that strong winds and steep 

 gradients do not occur near the centres of anticyclones. 

 From tfie opposition of the accelerations due respectively 

 to the earth's rotation and the curvature of the path, he 

 shows that there must be a limiting velocity and a 

 limiting gradient for anticyclonic areas, if it be granted 

 that the motion of the air adjusts itself to the gradient 

 velocity. 



The concluding pages of the report are devoted to a 

 graphic summary of the variation of the diiTerent elements 

 with height, as disclosed by the ascents carried out on 

 behalf of the Meteorological Office by Mr. Dines at 

 Oxshott in iqo6, and by ascents made at Lindenberg, 

 Berlin, and Blue Hill Observatory, U.S..\ 



There is one point to which we should like to refer 

 before concluding. Nobody can take up a paper like 

 the present one, which deals so largely with providing the 

 tools for future research, without" being forcibly struck 

 by the disadvantages of our English system of units, at 

 any rate for the purposes of dynamical'meteorology. Mr. 

 Gold invites us to measure the distance between isobars 

 for intervals of a tenth of an inch in millimetres. The 

 gradient velocity he gives us in metres per second, and 

 provides a subsidiary table for converting these to miles 

 per hour, the units adopted for wind velocitv in all 

 English meteorological publications, even in those" specially 

 devoted to the investigation of the upper air. He apolo- 

 gises for the incongruity in a special note, and explains 

 it on the score of convenience. Should our would-be 

 myestigator require to chart his results, our map-makers 

 will probably offer him outline maps on a scale of miles 

 to the inch, and a further troublesome reduction will 

 be necessary before he can apply Mr. Gold's tables. We 

 note with pleasure that the maps used by the Meteorological 

 Office for its working charts and dailv weather reports 

 are on a scale which is closely related to the natural 

 scale I :io'. We wonder whether other offices use similar 

 scales. The advantage of uniformity in such matters is 

 forcibly broiiifht home bv a report 'such as the one we 

 have described. 



THE WORK OF THE PHYSTKAIJSCH- 

 TECHNISCHE REICHSANSTALT IN iqo;. 

 'T'HE work accomplished by the Reichsanstalt last year, 

 as shown by the annual report of that institution 

 recently issued, appears to be of a character useful both 

 to physicists and to the industries which seek its assistance 

 in elucidating various technical problems. 



.^s regards the physical side of the work, the following 

 researches may be mentioned : — 



In accordance with a commission received by the in- 

 stitution, tests were started on the exact measurement 

 of very small pressures (of the order of between to-°" and 

 10-' mm.), the pressures being determined from the 

 deflection of a metallic membrane of 25 cm. diameter 



KG. 2024, VOL. 78I 



by means of the Fizeau interference method. The abso- 

 lute velocity of sound in dry air (free from carbonic acid) 

 has been investigated and found to be 33192 + 5 cm. per 

 second. Dr. Scheel has tested some further materials for 

 expansion between —191° and -l-i6° C. with the Fizeau 

 dilatometer described in the previous year's report, and 

 has obtained results varying from 2120 microns per metre 

 for palladium to —41 microns per metre for quartz glass. 

 Scheel and Schmidt have obtained a much lower value 

 for the refractive index of helium than that found pre- 

 viously by Lord Rayleigh and by Ramsay and Travers, 

 the figures of the former being 1-0000340. Some useful 

 work has been done in regard to the specific heat of 

 nitrogen, CO, and water-vapour, up to 1400° C, and 

 experiments to determine the saturation-pressure of water- 

 vapour above 100° C. have been commenced. 



In the Electrical Standards. Department the variations in 

 manganin resistances have been fotind to be very slight 

 and the " humidity effect " only just perceptible. Resist- 

 ance coils are now being wound on metallic spools with 

 longitudinal slots to render them somewhat flexible; in 

 this way it is hoped to make any effect due to humidity 

 practically negligible. Measurements of the wave-lengtn 

 of electric oscillations can be made with an accuracy 

 within I part in 1000 for long waves (above 1000 metres), 

 and for shorter wave-lengths the accuracy is within i per 

 cent. Other experiments have been made with undamped 

 electric oscillations produced after the Poulsen method 

 by means of an arc burning in oxygen. A research of 

 importance to opticians was carried out in regard to the 

 secular variation of the planeness of surfaces of optical 

 glasses, results being given in the report. 



In addition to the researches mentioned, a number of 

 routine tests w'ere carried out in the various departments 

 of the Reichsanstalt, some of these yielding interesting 

 results from a commercial standpoint. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 

 M.^N'CHESTER. — Dr. J. E. Petavel, F.R.S., has been 

 elected professor of engineering and director of the Whit- 

 worth laboratories. The following additional appointments 

 have recently been made : — Mr. T. G. B. Osbern, as lecturer 

 in economic botany ; Mr. C. H. Lander, lecturer in 

 engineering drawing: and Dr. F. H. J. .A. Lamb, senior 

 demonstrator in physiology. Dr. Hans Geiger has been le- 

 appointed to the Harling research fellowship in physics, 

 and Dr. Harry Osborne has been re-appointed a junior 

 research fellow in public health. 



The Department of Agriculture and Technical Instruc- 

 tion for Ireland has issued a circular to committees of 

 management of schools dealing with the question of the 

 liability of school managers and teachers in cases of 

 accidents to pupils in attendance at their schools. In a 

 recent action at law, damages were recovered from a 

 teacher on account of injuries received by one of his pupils 

 in consequence of a dangerous substance, used for scientific 

 experiments, having been left carelessly in the way of his 

 pupils. The department has been advised that teachers 

 may be held accountable for the accidents which may occur 

 as a result of allowing dangerous substances to be within 

 the reach of children so voung as to be likely to deal with 

 them in a manner causing injury, or for injuries which 

 may ensue as a result of negligence in allowing these 

 pupils to perform dangerous experiments without providing 

 reasonable safeguards against accident. The object of the 

 circular is to make teachers aware of their responsibility 

 so that all precautions may be taken to guard against 

 accidents to their pupils. Fortunately, it is easily possible 

 to devise suitable school courses of elementary science, in- 

 cluding no experiments of a dangerous character, and it 

 may be hoped that this timely warning may interfere in 

 no way with the suitable study of science by boys and 

 girls. 



.\v address on the teaching of the sciences and the 

 formation of the scientific spirit was given by Prof. Paul 

 .Appcll, president of the French Association for the Advance- 



