456 Mr. W. N. Shaw [Feb. 12, 



depressions were also given, including one which travelled up the 

 western coasts of the British Isles on October 14 and 15, and down 

 the eastern coasts on October 16 and 17, 1903, one which developed 

 from scarcely visible indications into a gale on December 30, 1900, 

 and one which disappeared, or " filled up," as it is technically called, 

 on February 6, 1904. The conclusion was drawn that the suggested 

 extension of the area of observation by means of wireless telegraphy 

 from ships crossing the Atlantic would not immediately place fore- 

 casting in the position of an exact science, but would add greatly to 

 the facilities for studying the life-history of depressions. 



The irregularities and uncertainties illustrated by the examples 

 given, might be attributed in part to the complexities of pressure due 

 to the iiTegular distribution of land and sea in the Northern hemi- 

 sphere. Charts of the mean isobars for the World for January and 

 July showed greater simplicity of arrangement in the Southern hemi- 

 sphere, where the ocean was almost uninterrupted, than in the 

 Northern hemisphere, where there were alternately large areas of sea 

 and land. The comparative simplicity of the South as compared 

 with the North was also illustrated by a chart representing an attempt 

 at a synoptic barometric chart for the World for September 21, 1901. 



The simplification of the barometric distribution at successively 

 higher layers of the atmosphere, as illustrated by Teisserenc de Bort's 

 chart of mean isobars at the 4000 metre level, was pointed out, and 

 illustrations were also given of the method of computing the baro- 

 metric distribution at high levels from observations at the surface, 

 using data obtained from observations at high level observatories, or 

 those made with balloons and kites. 



■ Some indication of the connection between the complexity of the 

 surface and the simplicity of the upper strata might be established 

 by means of careful observations of the actual course of air upon the 

 surface and the accompanying weather conditions. 



The actual course of air along the surface was often misunderstood. 

 The conventional S-shaped curves representing the stream lines from 

 anticyclonic to cyclonic regions were shown to be quite incorrect as a 

 representation of the actual paths of air along the surface. A diagram 

 contributed to the Quarterly Joiu'nal, Royal Meteorological Society,* 

 showed the computed paths for special case of a storm of circular 

 isobars and uniform winds, travelling without change of type at a 

 speed equal to that of its winds. An instrument made by the Cam- 

 bridge Scientific Instnmient Company to draw the actual paths of air 

 for a number of different assumptions as to relative speed of wind 

 and centre, and of incurvature of wind from isobars, was also shown, 

 and the general character of the differences of path exhibited under 

 different conditions was discussed. 



* The Meteorological Aspects of the Storm of February 26-27, 1903. Q. J. R. 

 Met. Soc. vol. xxix. p. 233, 1903. 



