80 Home Produce, Imports, Consumption , and 
commencement of our inquiry up to the present time. For 
1866, and for each year since, thanks to the exertions of the late 
Sir James (then Mr.) Caird, we have an official record of the area 
under the crop, in each division of the United Kingdom, and in 
the whole collectively, iu the “ Agricultural Returns ” annually 
published about the time of harvest. For the last twenty-six 
years, therefore, one element of uncertainty in any estimates of 
the home produce of wheat has been removed. 
The Average Yield of Wheat per Acre . — For 1884, and each 
year since, estimates of the average yield of wheat per acre in 
England, Wales, Scotland, Great Britain, Ireland, and the 
United Kingdom as a whole, have been published by the Board 
of Agriculture, in the “ Agricultural Produce Statistics.” But, 
prior to that date, the only returns or official estimates at com- 
mand relating to the subject were, for Scotland for four years, 
1854-57, and for Ireland for each year within the period of 
our inquiry ; whilst, for England and Wales, comprising in the 
earlier years from 85 to 90, and in the later nearer 95, per cent, 
of the total area under the crop, there was no official informa- 
tion whatever for any year prior to 1884, as above referred to. 
For this large proportion of the United Kingdom it was, there- 
fore, after very full consideration of the data, and of the results 
to which they led, decided to adopt the average produce per 
acre each year on certain selected and veiy differently manured 
plots, in the permanent experimental wheat field at Rothamsted, 
as the basis of the estimates of the average produce per acre 
each year ; and the same data have been relied upon in forming 
an estimate of the average produce over the United Kingdom 
as a whole. But, having regard to the character of the soil of 
the experimental field at Rothamsted, to the characters of the 
individual seasons, and to the consideration whether the season 
was more favourable for heavy or for light land, and so on, the 
estimate actually adopted for the country at large has, in some 
seasons, and especially in bad seasons, differed somewhat from 
the actual average indicated on the selected plots in the experi- 
mental field. Lastly, in all cases, the actual number of bushels 
per acre has been reduced by calculation into bushels of the 
adopted weight of 61 lb. per bushel. 
For detailed discussion, and for illustrations of the applica- 
bility of the data for the purposes of an estimate of the yield of 
the country at large, so far as evidence was available at that 
time after adopting them for a period of sixteen years, we must 
refer to our first paper on the subject published in the Journal in 
1868 ; and for further discussion, after the application of the data 
for a period of twenty-ei ght years, to our papers given in the J ournal 
