1>»S 



H. A. Hazen — Air-pressut\- at Ilif/Ji Shit'.onx. 



cause must produce the results or must act in conjunction with 

 the wind. Taking winds above sixty-one miles per hour I 

 have found ten cases in which the height was too small by 

 about fifteen feet; also, a great number of cases in which 

 though the wind continued strong from the same direction, yet 

 the computed height continually became less, showing that the 

 wind does not produce a direct effect upon the indications of 

 the barometer. 



-2.-./,:, A. to. .. 0.1 A. JC. A. cTT^ 



on with the 

 j uniformity 



in the occurrence of small and large differences of elevation 

 with the maxima ami minima of pressure, the least c-> 

 with high pressure and the greatest with low. Grouping a 

 second time, then, with respect to the maxima and minima 

 of pressure we have Table II. 



,, Dec, raeai 



In the above table, as the first two horizontal rows of figures 

 apply only to observations for the month of May, I have added 

 a third set of figures for the summit of Mount Washington 

 compared with the mean of Burlington and Portland as the 

 base, and computed for observations taken at 7 A. M.. 3 p. m. 

 and 11 P. If. Jan., Feb., Alar., Oct., 



Nov. and Dec, 1880. Burlington andJPortland, near sea-level, 



