SCIENTIFIC WEATHER FORECASTING. 3 



for France, which have no stations to the West of them, it 

 is extremely difficult. There are, moreover, " V shaped 

 depressions," "secondaries," and other varieties of distribu- 

 tion of pressure to be detected and taken into account, so 

 that on the whole a British forecaster probably requires 

 boldness as much as he needs knowledge. 



From the above very brief sketch of the principles of 

 Scientific Weather Forecasting, it will be seen that the 

 essentials are — (i.) Knowledge of the general principles of 

 atmospheric circulation ; (ii.) the use of weather maps ; (iii.) 

 the use of the electric telegraph. 



The fact that storm systems travel towards the east was 

 noticed at a very early date. Mr. R. H. Scott, F.R.S. (i) 

 says : — 



" The earliest notice of it which we can discover is an 

 entry on the map of Virginia, published in 1 747 by Lewis 

 Evans, to the effect that ' all our great storms begin to 

 leeward'. Franklin, in 1760, followed in the same strain, 

 but it appears that his attention had been caught at an 

 earlier period, in 1743, by the fact of his being prevented 

 at Philadelphia, by the clouds brought by a hurricane, from 

 observing a lunar eclipse, while the eclipse was seen at 

 Boston, which lies farther to the north-eastward, before the 

 storm came on." 



The first proposals towards the existing arrangements 

 seem to have been those of Lavoisier (2) about 1780, but 

 his suggestion included little knowledge of the laws of 

 atmospheric circulation, no weather map, and no electric 

 telegraph. He knew that a falling barometer generally 

 indicated wet weather, and a rising one fine weather, and 

 suggested that predictions based upon the motion of a 

 single barometer might be sent daily for publication in a 

 newspaper. Romme in 1793 {3) carried the proposal 

 farther, and suggested the use of Chappe's Aerial Telegraph 

 to "enable physicists to foresee the arrival of storms, and 

 to give notice of them to the ports and to farmers ". 



It is incapable of proof, but not improbable, that the 

 foregoing suggestions, and the investigation next to be 

 mentioned, were indirectly connected with the great work 

 carried out about that date by the Meteorological Society 



