'56 



NA TURE 



[July 12, 1906 



mountains. To these are now added observations made in 

 air altogether free. 



The distribution of the barometric pressure at a distance 

 of several thousand metres above the ground was first 

 examined, and maps were shown giving the isobars at 

 4000 metres as calculated from the pressure and tempera- 

 ture on the surface of the earth. 



M. Teisserenc de Bort has carefully verified that the 

 pressure in free air diminishes in accordance with the baro- 

 metric formula. For that purpose he determined the 

 heights of a large number of balloons by observing them 

 with two theodolites. On the average the heights thus 

 observed agree with those deduced from the barometers 

 carried by the balloons to within 2 or 3 millimetres of 

 barometric pressure for a height of 4000 metres. The 

 maps of the isobars at 4000 metres show that most of the 

 areas of high and of low pressure observed near the ground 

 become effaced as we rise in the air, and give place to a 

 pressure distribution of a much simpler kind, viz. a maxi- 

 mum of pressure all round the earth in the tropical regions, 

 and low pressures at the poles. The average direction of 

 cirrus clouds is in harmony with these conditions. 



As regards the distribution of temperature, the follow- 

 ing conclusions were established : — 



(i) Even at a height of several thousand metres above 

 the ground there is, contrary to what had been thought, a 

 very sensible variation of temperature from winter to 

 summer, the divergence of temperature between the coldest 

 and the hottest month being 9° C. at 10 kilometres height. 



(2) After it had been noticed that the rate of fall of 

 temperature increases with the height above the ground, it 

 was naturally supposed that temperatures at great heights 

 in the air were extremely low. But sounding balloons dis- 

 patched from the Trappes Observatory have proved that, 

 after a certain height, varying from g to 14 kilometres, the 

 fall of temperature ceases altogether — another fact that 

 was wholly unexpected. 



(3) The zone where the temperature ceases to fall, called 

 the " isothermal zone," is situated nearer the ground (8 to 

 q kilometres in certain places) with low pressures, and 

 further from the ground (about 12 or 13 kilometres) above 

 high-pressure areas. 



{4) As a general rule, it is colder in the upper part of an 

 anticyclone than it is at a corresponding height above low 

 pressures, but the contrary holds at medium heights of 

 about 5 kilometres. The absolutely lowest temperatures 

 are observed near high pressures. A temperature of —73° 

 has been observed several times at Trappes, and recently 

 as low as —80° in ."Xustria. 



(5) Balloon flights made daily for a week or more at a 

 time, in different years and at different seasons, have shown 

 that at intervals of a few days the atmosphere experiences 

 variations of temperature which are much more important 

 high up than on the ground. At a height of 11 kilometres 

 variations of 15° to 20° are often observed at a time when 

 variations of only 2° to 3° are found near the ground. 



It is believed that the arrest of the decrease of tempera- 

 ture is connected with the cessation at a certain height of 

 movements of the air having a vertical component, the 

 air then having movements which follow the isobaric sur- 

 faces. There is no longer any temperature variation due 

 to expansion or compression of the air. 



It has been demonstrated, alike by calculation of the 

 isobars and by the flight of balloons, that most of the 

 depressions which appear near the ground as complete 

 atmospheric vortices suffer deformation as the height in- 

 creases, and in their northern part lose themselves in the 

 great polar vortex ; so that, at a certain height (4 to 7 

 kilometres), east and north-east winds are no longer found 

 to the north of a depression, and the isobars at this height 

 form a handle attached to the low-pressure areas of 

 northern latitudes. On the front of a depression its 

 characters remain distinct to the top ; a sheaf of ascending 

 air reaches the height of cirrus cloud, and then spreads 

 over the barometric maxima to east and south-east. 



M. Teisserenc de Bort exhibited his verv light, compact 

 self-registering apparatus for measuring the temperature, 

 pressure, and humidity in the upper regions of the atmo- 

 sphere. Dr. W. N. Shaw, F.R.S., expressed the indebted- 

 ness of meteorologists to M. Teisserenc de Bort, whom he 



NO. I915. VOL, 74.] 



had come all the way from London to hear. After re- 

 ferring to the main points of the address, Dr. Shaw directed 

 attention to another important line of research for which 

 M. Teisserenc de Bort has fitted up a fish carrier, acquired 

 at Hull, with the aid of which he is investigating at the 

 equator the problem of the upper trade winds. 



INTERNA TIONAL SCIENCE} 

 T N an address delivered to the British Association at its 

 Belfast meeting in 1902 I expressed the opinion that 

 meteorology might be advanced more rapidly if all routine 

 observations were stopped for a period of five years, the 

 energy of observers being concentrated on the discussion 

 of the results already obtained. I am glad to say that 

 meteorologists have taken this remark as being meant 

 seriously, and its echoes still reach me from distant parts 

 of the earth. They disagree with me, but their disagree- 

 ment is of the apologetic kind. I do not wish to retract 

 or to weaken my previous statement, but merely to qualify 

 it now to the extent that it is only to be applied to two- 

 dimensional meteorology. There is a three-dimensional 

 meteorology as far removed from the one that confines 

 itself to the surface of the earth as three-dimensional space 

 is from a flat area. Three-dimensional meteorology is a 

 new science, which at present requires the establishment 

 of new facts before their discussion can properly begin. 

 The e.xtension of our range of observations by kites and 

 balloons is of comparatively recent origin. IVIr. Archi- 

 bald in this country was one of the pioneers of meteor- 

 ological investigation by means of instruments attached to 

 kites. In the United States Mr. Rotch, having established 

 a separate observatory, succeeded in convincing scientific 

 men of the great value of the results which could be obtained. 

 M. L. Teisserenc de Bort, who established and maintained 

 an observatory for dynamic meteorology at Trappes, near 

 Paris, rendered similar services with regard to " pilot " or 

 unmanned balloons carrying autographical instruments. 

 The aeronautical department of the Royal Prussian 

 Meteorological Institute, with Dr. .Assmann at its head, 

 under the direction of Prof, von Bezold, also made a 

 number of important contributions in the early stages of 

 the work. Prof. Hergesell, of Strassburg, similarly made 

 numerous experiments, and chiefly through the efforts of 

 those whose names have been mentioned, and more 

 especially Prof. Hergesell, an international agreement has 

 been secured by means of which kite and balloon ascents 

 are made in several countries on the first Thursday in each 

 month, and on three consecutive days during two months 

 of the year. \ large station for aeronautical work was 

 recently established at Lindenberg, near Berlin, where 

 kites or balloons are sent up daily for the purpose of 

 securing meteorological records. The greatest height yet 

 reached was during the ascent of November 25, 1905, when 

 by means of several kites sent one after another on the 

 same wire, the upper one rose to an altitude of 6430 metres, 

 almost exactly four miles. Owing to want of funds this 

 country could until recently only participate in this work 

 through the individual efforts of Mr. Dines, who received, 

 however, some assistance from the British Association and 

 the Royal Meteorological Society. The reconstruction of 

 the Meteorological Office has made it possible now for 

 Mr. Dines's work to be continued as part of the regular 

 work of the office, and further stations are being estab- 

 lished. Mr. Cave carries out regular ascents at his own 

 expense at Ditcham Park, and through the cooperation of 

 the Royal Meteorological Society and the University of 

 Manchester, assisted bv a contribution for apparatus from 

 the Royal Society Government Grant Fund, a regular kite 

 station is being established on the Derbyshire moors. 



The International Committee which collates the observ- 

 ations is a commission appointed by a union voluntarily 

 formed between the directors of meteorological observatories 

 and institutes of countries in which regular observations 

 are taken. The meeting of directors discusses schemes of 

 observations and encourages uniformity. 



If I mention a few of the difficulties which stand in the 

 way of a homogeneous system extending over Europe, I 



1 Discourse delivered at ehe Poval Institiilion on Friday, May 18, by 

 Prof. Arthur Schuster, F.R.S. (Continued from p. 237.) 



