46 ALLISON ON METEOROLOGY. 



on the 10th; while the 15th, mean 69°23, proved the hottest day. 

 Mean cloud decreased to 5.66, and the wind to 3.85 miles per 

 hour, returning to a S. W. prevalent direction. 2.29 inches was 

 the rain depth, almost the same as the average for July ; falling on 

 an ordinary number of days, 12. 



August again became colder, both absolutely and as compared 

 with former Augusts. Mean temperature 61°33. Mean pressure 

 of atmosphere, 29.854. This month was not so pleasant as July. 

 We had more cloud, mean 6.47 ; winds were light, giving a mean 

 of but 4.25 miles ; and S. was the prevalent direction. The rain 

 fall was still not large, being .29 below the normal, or 3.37 inches. 

 19 dry days were recorded. 



September scarcely varied at all from its mean temperature since 

 1863. This month gave 57°42, while 57°38 is my calculation 

 for the 12 Septembers. The temperature never fell below 40°, 

 and that not till the 24th. Pressure was rather great; mean 

 29.936. The brightness sensibly increased : mean cloud being 

 only 5.51. The returning N. W. wind gave evidence of the decay 

 of summer. The mean velocity of 4.97 miles per hour was very 

 small. A large quantity of rain fell on 12 days : 5.04 inches, 

 or 1.17 inches above the normal. The first autumnal gale was felt 

 on the 30th ; very heavy. 



October, as last month, resulted in temperature nearly the 

 normal. 48°74 was the mean ; and the pressure also continued 

 steady — 29.862. The month was very clear ; only 4.88 being the 

 mean clouding. We had a quiet month, the wind only giving a 

 mean of 4.48. miles, and the prevalent direction fell back to S. W. 

 The rain fall was very small, not half the normal which is 5.20 

 inches, while this October measured but 2.46 inches. This rain 

 was scattered over 13 days. No snow fell, generally we have 

 about half an inch in this month. A moderate gale blew from the 

 S. W. on the 30th — morning. The first hoar frost formed on the 

 7th, and the atmosphere first fell below 32° on the 23rd. 



November, though slightly colder than the average (which is 

 37°35, while this November's mean temperature was 36°77) was 

 a pleasant month. The mean pressure was very great: 29.900. 



