16 The Vegetation of the 



tinctive quality of winter we find its limits very variable in different 

 years. The mercury is falling below freezing point in a period commenc- 

 ing on the 1st of October and ending on the 11th day of May, so that the 

 first frost days in the thirty years occurred between the 1st of October 

 and the 12th of November; the last between the 25th of March and 11th 

 of May. 



The longest of those periods was in the winter from 1856 to 1857, 

 the first frost was noticed on the 1st of October and the last on the 11th 

 of May, a period of 223 days. 



The shortest was that from the 3d of November, 1877, to the 25th 

 of March, 1878, a period of 143 days. The former contained 142, the 

 latter only 51 frost days. Computing the average we find the first frost 

 day to be the 17th of October, for the last frost day the 17th of April, a 

 period of 18B days with 112 frost days, and 48 days with a mean tempera- 

 ture not rising above freezing point. 



SPEING. 



The mean temperature of the three spring months together is 50.2. 



The lowest mean was observed in 1857=43; the highest in 1878=56.6. 



The coolest March, 1867=29.5; the coolest April, 1857=39.9; the 

 coolest May, 1867=55; the warmest March, 1878=50.5; the warmest April, 

 1878=57.9; the warmest May, 1881=71.4. 



The mean temperature of the decades are in March lst^35; 2d=37; 

 3d^=41.8; the lowest was- the 1st in 1857^=22.3; the highest the 1st in 

 1878=55.5. April 1, 47.8, 2d, 51.7, 3d, 55.5; the lowest the lst=32.7; the 

 highest the 3d, 1879=66.2; in May. the lst=59.9, 2d=63.3, 3d=67.9; 

 the lowest the 1st in 1867=51.1; the highest the 3d in 1881, 77. 



The highest mean temperature of a single day of March was in 1875, 

 on the 30th=65.6, of April in 1872, on the 29th=77, of May in 1860, on 

 the 24=85.1; the lowest of March in 1867 on the 13th=4.7, of April in 

 1857 on the 6th=23.7, of May in 1875 on the lst=39.5. 



The highest stand of the thermometer was observed in March, 1860, 

 on the 30th=79; April 1865, on the 26th=88.5; in May 1860, on the 24th 

 =88.5. The lowest in March, 1867, on the 14th=_6; in April 1887, on 

 the 15th=18; in May 1867, on the 8th=30. 



There are, in average, 18 frost days in March; 5 in April, and, in May, 

 5 were observed in 30 years. The most frost days we had were in March 

 1859=29; and in April 1857=18. There was no frost day observed in 

 April 1878; only 13 p. c. of the frost days of April occurred after the 17th, 

 at which date, for the last time, a mean temperature below freezing point 

 was observed. 



SUMMEE. 



The mean temperature of the three summer months is 75.5. 

 The coolest summer was in 1866 and 1869=73; the warmest in 1874 

 =79. The coolest June in 1869=69; the coolest .July 1865=71; the cool- 



