70 Remarks on Mr DanielVs Hypothesis 
of our moist and changeable winters, proves so destructive to 
mountain plants, and not, as many have said, because the cover- 
ing of snow under which they are buried in their native sites, 
protects them from excessive cold. We thus see why, in the 
Arctic Regions, when plants are awakened into life by the return 
of the sun, they resume their organic functions with such 
amazing energy, that they spring, flower, and ripen their seeds, 
in the short space of six weeks. 
Our readers are now in possession of the leading facts, which 
are well authenticated, and it is for them to judge how far the 
first two questions have been satisfactorily answered. If we find 
Mr DanielFs to be without foundation, it is but fair to acknow- 
ledge, that the force of radiation from a vertical sun is not so ex- 
cessive as might have been supposed. We are still unable to 
give any solution to the most important of the questions proposed. 
What is the maximum calorific impressions which plants are sub- 
jected to in any latitude? Nor have we ascertained the force of 
the sun in any place on the surface of the earth. 
The experiments for this purpose are too delicate for ordinary 
hands, and, in our variable climate, more than one revolution of 
the season might take place, before an unexceptionable oppor- 
tunity might occur. Agriculturists and florists are well aware of 
how much consequence the agency of direct light is in the flower- 
ing of the Cerealia, and the brilliancy of ornamental plants. The 
absence of this important agent, as Mr Daniell observes, can 
never be compensated for by any elevation of temperature under 
a clouded sky. It is also well known, that, in many years in 
which the harvests are nearly mined, the average temperature 
does not fall below the ordinary mean of the year or of the sea- 
son. It is therefore highly important, that journals should be 
kept, in order to ascertain the effects of this powerful element in 
different years. For this purpose, the best arrangement that 
can be adopted is that used by Mr Daniell, with the exception 
of giving the instrument a free exposure to the wind : For the 
object being merely to ascertain the total amount of radiant mat- 
ter which plants have received during the day, the thermometer 
ought to be as nearly as possible in the same condition with the 
foliage and other parts of the plant. 
