208 Professor Hoffmann on the Geological 
much the more daring, inasmuch as astronomical reasons also 
are much against its probability ; for, if a certain alteration in 
the obliquity of the ecliptic has really taken place, La Place 
has proved that it was confined within fixed and periodically 
recurring limits, which he, agreeing with De Lambre, believed 
he might assume to be about 1° 29’. Another supposition 
which has been advanced to explain this problem is just as 
inadmissible, that the axis of rotation of the globe has been 
changed by a sudden shock ; for that such alterations cannot 
have been of magnitude, at least since the time when our 
earth was consolidated, is proved by the flattened form at the 
poles. 
A. von Humboldt believed, therefore, that in order to solve 
this problem, we must proceed from quite another basis, and 
he developed his ideas in an important paper on the disen- 
gagement of Caloric considered as a geognostical phenomenon. 
(Ueber die Entbindung des Wiarmestofs als Geognostisches 
Phénomen betrachtet.*,) He directed attention to the fact, 
that the original deposition of mighty mountain masses pre- 
supposes the evolution of a large quantity of free caloric ; for 
a body cannot pass from a state of solution into that of com- 
pactness, without at the same time losing a certain quantity 
of its heat, which was necessary to preserve it in its previous 
condition. This heat_set free must naturally have been com- 
municated to the nearest strata of the atmosphere. In 
his elucidations he proceeds from the fundamental principle, 
that all portions of the earth must have been dissolved in a 
common chaotic menstruum, whether that was in a liquid 
or an elastic (gaseous) condition. The first precipitation 
(produced by unknown causes) being regarded as given, 
had, by the consolidation of large masses, produced a consi- 
derable development of heat; this heat caused evaporation, 
and consequently a diminution of the volume of the liquid 
resting upon consolidated mass. Repeated precipitations 
were the result ; with each of these the temperature was at 
the same time elevated ; in fact, they would have continued 
to go on with constantly increasing rapidity, had not the ac- 
* Von Moll’s Jahrbuch der Berg-und-Hiittenkunde, iii. p. 115, 1799. 
