$i6 Dr. Herschel’s Observations to investigate 
be found very considerable; the first of them being nearly as 
4 to 3. 
The result of this review of the foregoing five periods is, that, 
from the price of wheat, it seems probable that some temporary 
scarcity or defect of vegetation has generally taken place, when 
the sun has been without those appearances which we surmise 
to be symptoms of a copious emission of light and heat. In 
order, however, to make this an argument in favour of our 
hypothesis, even if the reality of a defective vegetation of grain 
were sufficiently established by its enhanced price, it would still 
be necessary to shew that a deficiency of the solar beams had 
been the occasion of it. Now, those who are acquainted with 
agriculture may remark, that wheat is well known to grow in 
climates much colder than ours; and that a proper distribution 
of rain and dry weather, with many other circumstances which 
it will not be necessary to mention, are probably of much greater 
consequence than the absolute quantity of light and heat derived 
from the sun. To this I shall only suggest, by way of answer, 
that those very circumstances of proper alternations of rain, dry 
weather, winds, or whatever else may contribute to favour vege- 
tation in this climate, may possibly depend on a certain quantity 
of sun-beams, transmitted to us at proper times ; but, this being 
a point which can only be ascertained by future observations, I 
forbear entering farther into a discussion of it. 
It will be thought remarkable, that no later periods of the dis- 
appearance of the solar spots can be found. The reason however 
is obvious. The perfection of instruments, and the increased 
number of observers, have produced an account of solar spots, 
which, from their smallness, or their short appearance, would 
probably have been overlooked in former times. If we should 
