Contributions to Meteorology. 277 



meter for the month of January was 1.627 inches ; for February, 

 1.129 inches; for March, 1.340 inches; for April, 0.947 inches; 

 for May, 1.039 inches for June, 0.660 inches ; for July, 0.674 

 inches; for August, 0.714 inches; for September, 1.221 inches; 

 for October, 1.032 inches; for November, 0.856 inches ; and 

 for December, 1.241 inches. 



The greatest range within twenty-four hours, with a rising 

 column, occurred on the 21st January, and was 0.730 inches; and 

 the greatest range, with a falling column, was on the 10th of 

 January, and indicated 0.903 inches. The most sudden variation, 

 with a rising column, occured on the 18th of June, and from 3 

 p.m. to 3.20 p.m. (Twenty minutes) indicated a rise of 0.075 

 inches. The Symmetrical wave of November exhibited but little 

 fluctuation, the final trough terminated at 6 a.m. on the 30th day. 



Temperature of the Atmosphere. — The mean temperature for 

 the year was 40°. 04 Fahrenheit, which shows a decrease in tem- 

 perature of 0°.53 compared with the temperature of 1857, and 

 indicates 1°.520 less than the mean temperature for a series of 

 years. The lowest observed temperature was on the 13th of 

 February, and indicated 30°.2 below zero. The highest tempera- 

 ture occured on the 7th of July, and was 99°.3. giving a yearly 

 range or climatic difference of 12 9° 8. February was the coldest 

 February on record here, and indicated 14°05 colder than the 

 mean of last February, 1857. The h : ghest 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, 2 3° 5 2 ; for April, 39°.06 ; 

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

 66°. 12 ; for September, 59°. 13 ; 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°.7l less than the mean temperature of J bine. 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) was 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, 



