NATURE 



637 



THURSDAY, JULY 22, 1920. 



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Aerial Navigation and Meteorology. 



METEOROLOGY has been international ever 

 since it became a science. From the first 

 congress of directors of meteorological institutes 

 at Vienna in 1873, meteorologists have been en- 

 gaged in standardising methods of observation 

 and exposure of instruments, and in devising 

 codes for the transmission of observations 

 by telegraph in order to compress as much 

 ■valuable information as possible in the small space 

 available for transmission at moderate cost. So 

 the introduction of upper-air data, though strongly 

 recommended by those who wanted to substitute 

 calculation for "rule of thumb," had to fight its 

 way against other useful and more easily acces- 

 sible information of the older kind. The last 

 international code, fixed at Rome in 1913 after 

 long correspondence and discussion, kept the 

 morning message at four groups of five figures, 

 and allotted only one figure to upper-air data — 

 direction of high cloud^ — in addition to the cus- 

 tomary figure for weather or state of the sky. 

 For the benefit of aerial navigation, the results 

 of pilot-balloon ascents were telegraphed by many 

 European observatories to the central station at 

 Lindenberg. Funds for the telegraphic distribution 

 of these data and of those of soundings of the 

 atmosphere by means of kites or cable balloons 

 were usually lacking. 



The great war has changed all this ; aerial 

 navigation demanded quick and detailed informa- 

 tion, especially about low cloud, visibility, and 

 wind velocity in free air. Many reporting stations 

 were erected and connected to central offices by 

 telephone or wireless. Meteorologists sprang up 

 from the ground, the observational hours were 

 multiplied, and no one considered the cost. 



The result lies before us in the form of 

 NO. 2647, VOL. 105] 



Annexe G of the Convention for the Regulation 

 of Aerial Navigation, 1 the object of which is to 

 substitute legal regulation for free international 

 co-operation. The prominent features are : — 



(i) Regulation of the collection and dissemina- 

 tion of meteorological information — introduction of 

 four observational hours instead of two or three ; 

 of short-period (three to four hours) and route 

 forecasts (six hours) on one hand, and of long- 

 period forecasts (two or three days) on the other, 

 besides the normal forecasts (twenty to thirty 

 hours). 



(2) Extension of the number of groups in the 

 reports from individual stations to a central office 

 from four to six for all stations, and from four to 

 any number between twelve and forty-four for 

 stations observing upper-air wind, temperature, 

 and humidity. 



(3) Introduction of new codes for the new in- 

 formation and several of the customary data. 



Annexe G has been discussed at a meeting in 

 London of members of the pre-war International 

 Meteorological Committee, and again at the Con- 

 ference of Directors of Meteorological Institutes at 

 Paris in October, 1919; but definite resolutions 

 were postponed. We have reason to think, how- 

 ever, that the following remarks express the 

 opinion of a large majority of Continental meteor- 

 ologists and several of their British colleagues. 



There is practically no difference of opinion 

 about the necessity of reorganisation and central- 

 isation of the collection and dissemination of 

 meteorological information. Standard observa- 

 tional hours, quick transmission of the reports to 

 the national centre, exchange of collective reports 

 between centres with a maximum distance of 

 1500 km. within an hour and a half of the 

 observation, followed by selections from these 

 reports sent out over world-wide ranges by 

 a few high-power wireless stations within 

 three hours of the observation, is a good, but 

 not altogether new, scheme. Its complete realisa- 

 tion will be hampered only by the unsatisfactory 

 state of communication by telegraph or telephone 

 in some countries. The proposed simultaneous 

 transmission of several of the national collective 

 reports may cause the receiving stations to miss 

 part of them ; successive transmission may take 

 more time than the convention grants ; but these 

 are only technical details : the principle is all 

 right. Differentiation of forecasts also is neces- 

 sary, but it has to be adapted to local circum- 

 stances. 



1 " Air Ministry. Convention portant R^glementation de la Navigation 

 Adrienne (13 Octobre, iqig). Convention for the Kegulation of Aerial 

 Navigation (October 13, 1Q19)." Pp. 48. (Loiidon : H.M. Stationery 

 1 Office, 1920.) Cmd. 670. Price u. net. 



