Experimental Plots at Rothamsted, from 1864 to 1883. 397 
Tioentij-third Season, 1865-66. 
The very warm and dry weather of September, 1865, extended 
through the first week of October, and, although there were a 
few cold intervals, the temperatures of the three concluding 
months of the year ruled higher than the average, December 
especially being unusually warm. The period included how- 
ever very great fluctuations in barometric pressure, and some 
extremely severe storms of wind ; whilst in October an ex- 
cessive, in November a full, but in December a deficient 
amount of rain fell. January and the first half of February 
(1866) were also unusually warm, though in January there 
was a heavy fall of snow, which however rapidly thawed, and 
the whole period was very wet. A cold and drier period then 
set in, and extended to the middle of March, checking the 
hitherto much too forward vegetation. After this, to the end of 
the quarter, the temperatures, though variable, ruled, upon the 
whole, very high, and there was a full amount of rain. The 
beginning of April w as cold and rather wet. and the remainder 
considerably warmer and drier than the average. May was, 
throughout, unusually cold both by day and night, and there was 
a deficiency of rain. June was changeable, but included a good 
deal of hot weather, which raised the mean temperature above 
the average, and during the month a considerable excess of rain 
fell. The beginning of July was cold and wet ; then followed a 
week of hot and dry weather, but, from about the middle of the 
month to nearly the end of September, the weather, with the 
exception of a few short intervals, was generally cold, with 
a good deal of rain and wind in August, and an excessive, and 
almost continuous fall in September. October was, however, 
upon the whole, warmer and drier than usual. In June, July, 
August, September, and October the degree of humidity of the 
air was generally high. 
Thus, after a very wet and comparatively warm autumn, the 
winter was, until the middle of February, unusually warm, with 
a great deal of rain, inducing premature luxuriance of grass and 
winter sown crops ; then came a month of cold and dry weather, 
checking growth. The remainder of the spring was at first very 
variable, but May was unusually cold and dry. The early 
summer was changeable, but mostly warm, Avith a good deal of 
rain ; and the ripening and harv^est periods were almost con- 
tinuously cold and rainy, with a moist atmosphere, but with 
occasional high and drying winds. 
The wheat crop of 1866 was one of inferior yield under all 
the different classes of manures, the highest produce of any one 
plot not reaching 33 bushels ; while the estimated yield of the 
