264 CONTRIBUTIONS TO METEOROLOGY. 



129°8. February was the coldest February on record here, and 

 indicated 14°05 colder than the mean of last February, 1857. The 

 highest degree of temperature for the month was 39°.4, and the lowest 

 30°.2 below zero. The most sudden decrease of temperature occurred 

 on the 18th of June, and indicated in twenty minutes a decrease of 

 17°,1 ; the thermometer standing at 3 p.m. at 93°8, and at 3.20 p.m. 

 76°. 7. The mean temperature of the air for the month of January 

 was 13°.76; for February, 7°.56 ; for March, 23°52 ; for April, 

 39°.06 ; for May, 63°.02 ; for June, 67°.21 ; for July, 66°.50 ; for 

 August, 66°.12; for September, 59M3 ; for October, 46°48 ; for 

 November, 26°78 ; and for December, 12°.37. July which has for a 

 series of years indicated the greatest mean temperature showed this 

 year 0°.71 less than the mean temperature of June. This was owing 

 to the low temperature accompanying the excessive rain of the month 

 of July. 



Humidity. — The relative mean humidity of the atmosphere for the 

 year (saturation being 1,000) 0.778. July indicated 0.074 of moisture 

 more than the mean of a series of years. The mean humidity for 

 the month of January was .786 ; for February, .703 ; for March, .789 ; 

 for April, .717 ; for May, .7^4i ; for June, .756 ; for July, .818 ; 

 for August, .818; for September, .804; for October, .792; for 

 November, .809 ; and for December, .787. Complete saturation occur- 

 red in July, and is the only instance on record here of such an occur- 

 rence. 



Rain fell on 111 days, amounting to 50,035 inches on the surface. 

 It was raining 521 hours 33 minutes, and was accompanied by thun- 

 der and lightning on 20 days. This amount of rain exceeds by 

 upwards of 7 inches the usual average amount compared with a series 

 of years, and was owing to excessive rains in June and July. 



A very heavy storm occurred on the 10th of June, which lasted 28 

 hours and 48 minutes, and amounted to 6.175 inches. There fell in 

 one hour (from 5 to 6 p.m.) 0.933 inches, and from 6 p.m. to 7.2S 

 p.m. the amount of 1.333 inches. The river surrounding this Island 

 rose 8 inches in height. 



Another storm of heavy rain set in at S a.m. on the 12th day of 

 July, and ceased at 12.40 p.m. of the 13th, and indicated a depth of 

 rain on the surface of 6.374 inches ; it was accompanied by a N.E. by E. 

 wind. The river in the neighborhood rose nearly 2 feet in perpendicu- 

 lar height, and the amount of rain which fell during this month was 



