32 



These advantages, at Mount Washington, we find in 

 the elevation of more than a mile above sea-level, and 

 that it so nearly reaches the line of perpetual snow, in the 

 considerable height over the surrounding peaks ; in the 

 summit being usually above the lower surface winds and 

 lower cloud stratum. 



As it is, to a certain extent within the region of the 

 higher upper currents, barometric, thermometric and 

 hygrometric conditions obtain, which do not at lower 

 stations, or in the same time and degree, and of value in 

 connection with them in forecasting storms. 



BAROMETRIC OBSERVATIONS. 



It is well understood that changes in the velocity of the 

 wind and amount of cloud, exercise a marked influence 

 upon the barometer. These disturbing elenients being 

 in full force here, hence the sensitiveness of the in- 

 strument and its fluctuations, as well as its wide range. 

 Its sensitiveness is best seen in a nearly calm day when 

 clouds are drifting over ; then the mercurial column will 

 not rest for a moment, and yet the range for an hour may 

 not be more than .002 to ,004 of an inch. The fluctua- 

 tions during a gale are very great, frequently from one 

 half hour to another, half an inch or more. The range 

 from December 1st, 1870, to May 14th, 1871, was 1.595 

 inches. The lowest reading corrected for temperature 

 was 22.120 and the highest was 24.104. The first was 

 during the great gale of December and the last towards 

 the latter part of May. It has a wide range in the great 

 gales, or hurricanes of winter, but not in the summer 

 storms. 



Almost hourly observations were taken from 11 A.M., 

 January 22d, to 9.30 A.M. of the 23d. This was one of 

 the three great gale's. The range was 1.116. The long- 



