398 
On Solar 
which it is the object of this paper to describe, was devised by 
Sir John Herschel, the distinguished astronomer; and from the 
correct philosophical principles on which it is constructed, and 
its uniform and sure indications, it has already met with much 
success. 
That the intensity of light and heat from the sun does vary 
most materially in different climates, is clearly a matter of in¬ 
ference from the differences of temperature, but that they do not 
vary in the same ratio is also an established fact, because in many 
places, where from geographical position the solar heat may be 
inconsiderable (as in the Polar regions), the intensity of the solar 
light is often unusually great, and vice versd —the latter being 
much dependent in its intensity upon a variety of atmospheric 
causes, such for instance as the phenomena of the vapour in dif¬ 
ferent climates, and under different circumstances of situation, 
whether insular, littoral, or continental. However, speaking ac¬ 
cording to our ordinary sensations, we are accustomed to say 
that the sun communicates both light and heat, although even 
now we have but a confused idea of the actual connection existing 
between them; but as they both exert considerable influence 
upon the productions of the vegetable kingdom, and by having a 
true knowledge of the relative heating power of the sun's rays, 
much valuable information may be obtained in various climates, 
as to what fruits, or vegetable productions, can be most profitably 
introduced, it becomes a subject well worthy of investigation. 
In these colonies, so unusually barren of naturally useful pro¬ 
ductions—so totally devoid of indigenous fruits, grain, or roots, 
fit for human food—the investigation becomes of much importance 
in a practical point, as probably expense and time might both be 
saved, to many enterprising persons, if they could receive un¬ 
questionable assurance, founded on correct data, that the intro¬ 
duction of certain plants, or fruits, would be successful; and 
although it is not the object of the writer of this paper to take 
upon himself to give any opinion on such a very important sub¬ 
ject, still he would point it out as one of the great practical results 
which will be ultimately obtained from the careful and laborious 
system of meteorological observation, which has been carried on 
