^ M. Humboldt on Isothermal Lines ^ and the 
will be of considerable importance to fix the numerical relation 
by which a great number of scattered observations are connect- 
ed, and to reduce to empirical laws the effects of local and dis- 
turbing causes. The study of these laws will point out to tra- 
vellers the problems to which they should direct their principal 
attention, and we may entertain the hope, that the theory of the 
distribution of heat will gain in extent and precision, in propor- 
tion as observations shall be more multiplied, and directed to 
those points which it is of most importance to illustrate. 
As the phenomena of geography and of vegetables, and in 
general the distribution of organised beings, depend on the 
knowledge of the three co-ordinates of Latitude, Longitude, and 
Altitude, I have been occupied for many years in the exact 
valuation of atmospherical temperatures; but I could not re- 
duce my own observations without a constant reference to the 
works of Cotte and Kirwan, the only ones which contain a great 
mass of meteorological observations obtained by instruments 
and methods of very unequal precision. Having inhabited for 
a long time the most elevated plains of the New Continent, I 
availed myself of the advantages which they present for exa- 
mining the temperature of the superincumbent strata of air, 
not from insulated data, the results of a few excursions to 
the crater of a volcano, but from the collection of a great 
number of observations made day after day and month after 
month in inhabited districts. In Europe, and in all the Old 
World, the highest points of which the mean temperatures 
have been determined, are the Convent of Peissenberg in Bavaria, 
and the Hospice of St Gothard The first of these is placed 
at 3264, and the second at 6808 feet above the level of the sea. 
In America a great number of good observations have been 
made at Santa Fe de Begota and at Quito, at altitudes of 
8,727 and 9,544 feet. The town of Huancavelica, containing 
10,000 inhabitants, and possessing all the resources of modern 
civilisation, is situated in the Cordilleras of the southern hemi- 
* The mean temperature of the air at the Convent of the Great St Bernard, the 
height of which is 7,960 feet, is not determined. There are several villages in 
Europe placed at more than 5000 feet of altitude ; for example, St Jacques de 
Ayas at 5;'1<79, and Trinita Nuova, near Grasfoncy, at 5,315 feet. — H. 
