420 SCIENTIFIC RECORD FOR 1882. 



per liour; tlie IiigL^st squall, 71. G miles. He observed these velocities 

 by means of clouds of smoke rising from cbimueys, {Nature, xxrv,'p. 102.) 



Whipple and Baker communicate to the London Meteorological Soci- 

 ety the results of the discussions of the Jvew observations of the wind. 

 They find that the wind force increases arithmetically with the increase 

 of the gradient; and again, that the angle at which the wind crosses the 

 line of gradient averages 52°, and does not var}' with the steepness of 

 the gradient or the velocity of the wind. {Nature, xxv, p. 319.) 



The committee on wind-pressure report to the Brit. Assoc. A. S. that 

 the maxiaium pressure of wind on small plane surfaces had been ascer- 

 tained to exceed 90 pounds to the square foot, and it is possible that an 

 average of 56 i^ouuds might hold good for the whole surface of very ex- 

 i:)Osed structures. {Nature, xxv, p. ilS.) 



VIII. — Barometric pressure. 



Mr. H. S. Eaton has published a paper on the average height of the 

 barometer in London. The great value of the i^aper consists both in 

 the long period of one hundred years for which the monthly averages of 

 each year are given, and in the careful and laborious elimination of in- 

 strumental errors and errors arising from breaks of one or more days 

 in the observations of the months. The series is one of the most valu- 

 able we possess in dealing- with questions of meteorological variations. 

 The mean atmospheric pressure at 32° and sea-level for London is 29.952 

 inches, the mean monthly maximum, 29.990 inches, occurring in June, 

 and the minimum, 29.900 inches, in Novendjer, the mean for October 

 being nearly as low, viz, 29.909 inches. In a discussion which followed 

 a reading of the paper, Mr. Strachan remarked that even another one 

 hundred years' observations would not alter the positions of these points 

 of the London curve, a remark no doubt quite true for London. On 

 advancing, however, to the southwest, the means for June and July 

 approach towards equality, and ultimately the Julj' mean becomes 

 larger as we advance into the region of high pressure, which occupies 

 the Atlantic to the southwest during this month. On the ether hand, 

 as we approach northward, the means for May and June approach 

 towards equality, till about the south of Scotland the mean for May 

 becomes the maximum for the year, and the further north the more 

 decidedly is May the maximum, till in Iceland it exceeds the mean of 

 any other month by the tenth of an inch. Attention was drawn to the 

 dips in the curves of pressure for April and July. These, in all proba- 

 bility, are permanent features in the London curve of pressure for 

 March, April, and July, when drawn from a long average, since the 

 former is connected with the east winds of spring, and the latter with 

 the great summer barometric depression, which falls to the lowest point 

 in July in the interior of the Europo-Asiatic continent. {Nature, De- 

 cember 23, 1880, XXIII, p. 184.) 



An important work by the late J. Allan Broun has been published 



