72 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



mcnts of the clouds continues to be frequently urged. Cle- 

 ment Ley calls for as many co-operators as possible in this 

 work, and Broun has carefully discussed his own most exact 

 observations. Hildebrandsson has published, with numerous 

 charts, a new edition of his studies into the movements of 

 the upper currents of the atmosphere. None of these works, 

 however, seem to be comparable in extent and importance 

 with the magnificent series of maps that have now for seven 

 years been published thrice a day by the Army Signal Office. 

 These maps and the accompanying bulletins show the direc- 

 tion of the winds, the lower clouds, and the upper clouds ; 

 and as early as May, 1872, the author announced the law that 

 the upper clouds moved towards a point to the right of the 

 direction of the lower clouds, and subsequently that the low- 

 er clouds also moved to the right of the surface winds. He 

 also stated that the prevalent mistaken idea that the upper 

 currents were all from the west, or that a steady west cur- 

 rent prevailed at great altitudes, arose from studying only 

 cirrus clouds, which were, at least in the United States, gen- 

 erally found on the west sides of centres of high pressure 

 (see Bulletin Phil. Soc, Washington, 1871). The exact incli- 

 nation of direction of lower cloud movement to the winds 

 was first determined by Redfield in 1833-39, as about 7. 

 In the previous year Redfield had estimated at 45 or less 

 the angle between the winds and the radius drawn to the 

 storm-centre. 



Buys-Ballot has published an extended discussion of the 

 relation between the theory and observation relative to the 

 connection between barometric pressure and the wind. To 

 a certain extent this is an examination into the truth of the 

 law known as Buys-Ballot's law, and published by him in 

 1857. This law has been so often modified by others as to 

 have quite lost the simplicity of the wording of the author, 

 who originally announced it thus: "When at two stations 

 in Holland the deviations from normal pressures are un- 

 equal, the wind will, within twenty-four hours, be found to 

 blow at right angles to, or within 30 on either side of, the 

 line joining these." According to his present investiga- 

 tions, Buys-Ballot finds that the east and northeast winds 

 set in less promptly than the west winds; and with regard 

 to the gradients, he finds that these winds need a steeper 



