RECOMMENDATIONS. 
51 
numerous observations. The observer may be referred 
for information to Ram on d, Memoires sur la Formule 
Barometrique de la Mechanique Celeste ; to the Re¬ 
searches of Humboldt; to Professor Leslie, Supplement 
to the Encyclopcedia Britannica , Article Climate ; to 
Pouillet, Elemens de Physique ; to Mr. Atkinson’s 
Paper on Refractions in the Memoirs of the Astronomical 
Society ; and to Mr. Ivory’s Memoir on the same subject 
in the Philosophical Transactions , and his Papers in 
the Annals of Philosophy. 
VII. That the observation of the Temperature of Springs at 
different heights and depths should be pointed out as an 
object of great interest, in prosecuting which insulated inquirers 
may render essential aid to science. 
Note. When springs are copious, a few observations in the 
course of the year suffice to give with great accuracy 
their mean temperature. The height of the springs 
above the mean level of the sea, and the depth of 
Artesian wells, should be carefully observed; and where 
the corresponding mean temperature of the air can be 
obtained, it should be stated. In two points of view 
these observations are important, independently of the 
inferences which they may furnish as to the decrease of 
heat in the atmosphere. The great interest attached to 
the phenomenon of the progressive increase of tempera¬ 
ture of the globe, as we descend through the Strata, 
renders of value observations on the temperature of 
springs at considerable heights, of springs in mines, and 
of those brought to the surface from some depths by the 
process of boring. This question has been treated with 
great success by M. Cordier, in several Memoirs, some 
of which have been translated into English. Again, the 
researches of Humboldt, Buch, Wahlenberg, and most 
recently Kupffer in a Memoir on Isogeothermal Lines , 
read before the Academy of St. Petersburg, in 1829, 
have shown that the temperature of the earth differs in 
many parts of the globe from that of the air, being 
generally in defect below lat. 56°, and in excess beyond 
it. The progressive increase of temperature with that 
of the depth in Artesian wells, and the deviation of the 
mean temperature of the Earth from that of the Air in 
different latitudes, have opened new fields for discussion; 
and by the zealous cooperation of observers cannot fail 
to present results, of which at present we can form but 
an imperfect idea. 
d 2 
