Our Climate and our Wheat-Crops. 
175 
each of two seasons, will have a very widely different effect on 
vegetation in the two cases, if the one season should be at the same 
time a hot and the other a cold one. Or, if the temperature of 
the two seasons be the same, but the rainfall very different, so 
also will the effect on vegetation be very different. It is generally 
supposed that the temperature of our summers is not, on the 
average, sufficiently high for the production of abundant and 
well-ripened crops of wheat ; and that it is in the hottest seasons 
that the produce is the most abundant. This may be the case 
so far as a certain class of soils is concerned. But a good deal 
of wheat is grown upon light land, on which the crop suffers 
considerably in a season of drought or unusual heat. It would 
appear that the defect of our climate for the production of 
wheat is more connected with an excess of moisture than 
with a deficiency of heat, during the periods of active growth 
and maturing. It is, in fact, when a cold season, or one of only 
moderate temperature, is acompanied by an excess of rain, that 
we find the yield of our wheat-crops is the most defective. 
I. Seasons op High and of Low Productiveness. 
Before entering upon any detailed consideration of the pecu- 
liarities of the season and of the experimental wheat-crops at 
Rothamsted, in 1879, we will endeavour to illustrate, in broad 
outline, the general characters of season under which some of 
the best and some of the worst wheat-crops of which we have 
the record, or the experience, have been grown in this country. 
For this purpose we will disregard any special characters of the 
seasons in question at Rothamsted, and draw our illustrations 
entirely from independent data ; namely, the records of the 
observations of temperature and rainfall made at the Royal 
Observatory at Greenwich ; and we adopt for the most part 
those published by Mr. Glaisher. It is obvious that even such 
data are more or less local in their application ; still, they do 
indicate the general character of the different seasons, and their 
distinction from one another. 
In Tables I. II. and III., which follow, are given the parti- 
culars of the temperature and rainfall of fourteen seasons during 
the present century, each of which was more or less remarkable 
so far as the growth of the wheat-crop is concerned. These are 
1816, 1832, 1833, 1834, 1835, 1853, 1854, 1857, 1860, 1863, 
1864, 1868, 1870, and 1879. The first and the last of them, 
1816 and 1879, have the character of yielding the two worst 
wheat-crops witbin the period included by those dates, if not 
indeed within the century. Some of the others were, also, 
seasons of great deficiency ; but others, though, as will presently 
