114 ^^^ American Geologist. February, 1901. 
angles. Such a network Elie de Beaumont called his pentago- 
nal network, and he used it in the following way. He studied 
the mountain ranges of the world, and by elaborate calcula- 
tions showed their relative directions at a few localities which 
he chose as centres of comparison. He found that many 
mountain ranges have the same orientation, and that others 
cross the first set at definite regular angles. The directions 
of the different sets of mountain ranges coincide with the lines 
of his pentagonal network. Elie de Beaumont claimed that 
the mountains whose directions are parallel,''' were formed at 
the same date. Successive mountain-forming movements 
raised chains parallel to different edges of the network ; and 
thus the intersecting mountain lines of the world, and, conse- 
quently, the forms of the continents, were determined. 
Elie de Beaumont had no difficulty in pointing out striking 
coincidences between important geographical lines and his pen- 
tagonal network. Thus the Mediterranean volcanic axis, pass- 
ing through the Grecian archipelago, Etna, and Teneriffe, is 
parallel to the Alpine chain, and at right angles to the circle 
through Etna, Vesuvius, Iceland, and the Sandwich Isles. He 
was able to show a close geometrical relationship between those 
lines and the line of the Andes, with the pentagon that covers 
Europe. That the earth is traversed by great intersecting lines 
is undeniable. E.g. Daubree showed that the valley system of 
northern France follows a line of rectangular fractures, which 
he called diaclases. The directions of the Greenland fiords is 
determined by a similar series of intersecting diaclastic frac- 
tures. Bertrand has shown that the movements in the Paris 
basin, the North sea, and English channel, have follow^ed a 
double set of orthogonal intersecting lines. 
But that the fracture lines or lines of weakness in the earth's 
crust should intersect more or less rectangularly is natural on 
any theory of their formation. And such coincidences as those 
pointed out by Elie de Beaumont in support of his system are 
inevitable in so crumpled a globe as ours ; but they are not suf- 
ficiently numerous to be convincing, especially in face of the 
fundamental differences between the facts of geography and 
Elie de Beaumont's elaborate artificial system. His theory could 
*For explanation and justification of this use of the word "parallel," see 
Hopkins, "Presid. Address, Geol. Soc," Quart. Jour. Geol. Soc, vol. ix. p. xxix. 
