May 24, 1858.] PHYSICAL GEOGRAPHY— CHANGES OF THE SURFACE. 327 
sinned to exist in tlie unknown regions traversed by any great 
circle, make up very nearly the amount just mentioned of 100°; 
and moreover, that all such great circles are each characterized by 
very nearly the same number of transverse lines ( alignements ter - 
restres ) which run perpendicularly to the great circle, and are 
marked by salient points of the earth’s surface, or are recognised as 
lines of volcanic action, or lines along which, at least, earthquakes 
are not of unfrequent occurrence. M. de Francq also finds (2) that 
those great circles along which the terrestrial lines of elevation con- 
stitute together an arc of more than about 100° are not accompanied 
by the transverse alignements terrestres , but by others which are 
parallel to their own directions respectively. These appear to be 
two of the principal generalizations at which M. de Francq has 
arrived respecting the existing geographical distribution of land 
and sea ; and one of the most interesting deductions from them may, 
perhaps, be stated to be that which he draws respecting the pro- 
bable existence of considerable tracts of land in the polar regions. 
He finds that those great circles of the first class above mentioned 
which traverse the polar regions are most defective in the extent of 
their known lines of elevation, but the whole arc above mentioned of 
100° is made up in such cases by the calculated probable extent of 
such lines in the unknown polar regions. The harmony thus estab- 
lished between the great circles which traverse the polar regions, 
and those which lie without them, is regarded by M. de Francq as a 
proof of the truth of the hypothesis that a considerable extent of 
land exists in the neighbourhood of one or both the poles of our 
globe. 
One of the great objects of my intelligent and indefatigable friend 
the Baron de Francq in publishing the ingenious memoirs* which he 
has successively laid before the French Academy of Sciences, the 
application of his theory to some of the great geological features of 
the globe, as specially indicated in the last of these communications, 
cannot now be adequately discussed. The consideration of this 
vast subject, on which the eminent geologist Elie de Beaumont has 
written so ingeniously in propounding views which M. de Francq 
supports, would occupy in fact a large part of a purely geological 
discourse. The physical data, however, which the author has 
arranged and discussed with great perspicuity and infinite pains, in- 
* De la Formation et de la Repartition des Reliefs Terrestres, Mem. de l’Aca- 
demie des Sciences, 28 Fev., 24 Mars, 2 Juin, 1856, et 15 Mars, 1858. See also 
Bull, de la Soc. Geol. de France, 2 ser., t. x., 1853. 
VOL. II. 2 C 
