36 



six to thirty-six hours earlier on Mount Washington than 

 at lower stations. High and low temperatures are regis- 

 tered here, which we shall notice under winds, that do 

 not descend to lower levels. On the other hand low tem- 

 peratures are observed below when there is no change on 

 the mountain. This we shall explain further on. So 

 there are cold terms when the minimum is lower at some 

 not distant stations than here. 



As with the barometer so the thermometer has no fixed 

 hours of daily maxima and minima. At Mount Washing- 

 ton there were seventeen days when the maximum was 

 attained at 2 P.M., to ten at 7 A.M., and nine at 9 P.M., or 

 when the readings were the same as at 2 P.M. At Mon- 

 treal, twenty-nine at 2 P.M., to two at 7 A.M., and five at 

 9 P.M. At Hanover, twenty-three at 2 P.M. to four each 

 at 7 A.M. and 9 P.M. In winter the changes are sudden 

 and great ; often in a half-hour from 5 to 25 and at any 

 period of the twenty-four hours. The change of temper- 

 ature from Sunday morning, February 5th at 3 o'clock, if 

 we call it at that hour, 54, to Tuesday noon follow- 

 ing, when the thermometer indicated, in the sun, 62, was 

 116. Thirty to forty degrees difference in a day is of 

 common occurrence. 



HYGROMETRIC OBSERVATIONS 



Were made with great care. During the winter we used 

 wet and dry bulb thermometers hung side by side, and 

 after the warm season opened the Mason Hygrometer. 

 With all our care these froze and so were ruined. For 

 that locality the ordinary wet and dry bulbs are most con- 

 venient at all times and in that moist climate require but 

 little attention. Of these observations, Professor Cleve- 

 land Abbe, of the Signal Office, Washington, has said 

 "the hygrometric observations from the mountain stations 





