2,66 Dr. Herschei/s Observations to investigate 
flowing waters of that wonderful river ; and so, in the case of the 
sun’s influence, we are likewise fully aware, that we shall never 
be able to occasion the least alteration in the operations which 
are carried on in the solar atmosphere. But, if the Egyptians 
could avail themselves of the indications of a good Nilometer, 
what should hinder us from drawing as profitable consequences 
from solar observations ? We are not only in possession of photo- 
meters and thermometers, by which we can measure from time 
to time the light and heat actually received from the sun, but 
have more especially telescopes, that may lead us to a discovery 
of the causes which dispose the sun to emit more or less copi- 
ously the rays which occasion either of them. And, if we should 
even fail in this respect, we may at least succeed in becoming 
acquainted with certain symptoms or indications, from which 
some judgment might be formed of the temperature of the 
seasons we are likely to have. 
Perhaps our confidence in solar observations made with this 
view, might not exceed that which we now place on the indica- 
tions of a good barometer, with regard to rain or fair weather ; 
but, even then, a probability of a hot summer, or its contrary, 
would always be of greater consequence than the expectation of 
a few fair or rainy days. 
It will be easily perceived, that in order to obtain such an 
intimate knowledge of the sun as that which is required for the 
purpose here pointed out, a true information must be first pro- 
cured of all the phenomena that usually appear on its surface. 
I have therefore attended to many circumstances, that have 
either not been noticed at all before, or have not been examined 
with any particular view of information. The improvement also 
in the solar apparatus of my ten-feet telescope, by which I can 
