346 
The average crop divided by the average rainfall of the preceding 
year shows that each inch of rain corresponds to about 800 hogs- 
heads in the resulting crop; the extreme limits of variations are 713 
and 877 hogsheads, so that in general Governor Rawson proposes 
to predict the crop that will be gathered during the dry season, 
February to May, each year by simply multiplying the rainfall 
of the preceding calendar year by 800. The average uncertainties of 
the crop thus predicted is very small, the extreme error being 28 
per cent positive following the wet year 1861 and 4 per cent negative 
for a certain dry year; therefore as an improvement on this method 
he adopts the rule of adding 7 per cent for wet years and subtracting 
7 per cent for dry years, the average year being that which corre- 
sponds to 55 inches of rainfall. 
In supplementary calculations Rawson and Walcott show the 
chances of a good crop as calculated from a large, small, or average 
rainfall, respectively, for each month of the year, but I do not find 
that they have at any time compared the crop with the total rainfall 
for the whole eighteen months or growing period that immediately 
preceded the crop, which comparison I have therefore made and 
give in Table IIT. 
From all which it appears that large rains gives large crops, but 
occasionally much smaller rains do also, so that it may reasonably 
be suspected that here, as elsewhere, the sunshine must be considered ; 
probably large rains are only of advantage when they occur at such 
a time that they do not diminish the sunshine and in such a manner 
that they do not wash the soil too severely. 
It would have been desirable to have stated these crops as yields 
per acre rather than as total crops, but I find no statement of the 
actual acreage in cane. Rawson gives only the total areas of the 
six divisions of the island, which sum up 107,000 acres; probably 
two-thirds of this is planted in sugar cane, so that an inch of annual 
rainfall corresponds to ~8°°,, or one-ninetieth of a hogshead_ of 
sugar per acre. 
It is, however, more proper to reason upon this matter as follows: 
Eleven poor crops gave, according to Table I, an average deficit of 
15 per cent; 12 good crops gave an average excess of 14 per cent; 
the average rainfalls were 55.15 and 58.18, respectively. Therefore 
an increase of 1 inch in rainfall corresponds to a gain of 2,4, or 10 
per cent of an average crop. 
