2l6 The American Geologist. ^i'"'- i^^s 
From the oral statements in this and other unpublish- 
ed addresses, Prof. Herman L. Fairchild, secretary of the 
Geological Society of America, presented on January i, 
1904, at the sixteenth annual meeting of that society, an 
able discussion of the geologic bearings of the new hypo- 
thesis.* 
The recent detailed publication of it, in Year Book 
No. 3 of the Carnegie Institution, from which I have so 
largely quoted, has no diagrams or other graphic illustra- 
tions; but such desirable aids for the more definite develop- 
ment of the subject, with ample treatment of its relations 
to geology, are intended to be published soon, in the second 
volume of a geological text-book by Professors T. C. 
Chamberlin and R. D. Salisbury, whose first volume of 
this work was issued early last year.t 
Chamberlin has contributed greatly to the establish- 
ment of an acceptable nebular theory, consistent with the 
known relations of the planets, their satellites, and the 
sun, by his derivation of the solar system from a* spiral 
nebula, and by his indicating the probable mode of origin 
of such nebulae, which abound by tens of thousands 
throughout the starry heavens, as discovered by the most 
powerful telescopes. 
Both the meteoritic hypothesis of Lockyer and the 
planetesimal hypothesis of Chamberlin seem to me prob- 
ably true in their regarding the nebulous matter from 
which planets and suns are made as having become mostly 
solid, though finely divided, and as very cold, being in 
almost absolutely cold and immensely extended space, 
previous to the condensation and segregation which form- 
ed it into worlds and stars. 
During the accumulation of the planets and their 
satellites, much or perhaps nearly all of the nebulous 
matter forming them had remained, until thus gathered 
as great bodies, apparently in solid and cold molecules or 
in small masses brought together by their gravitative at- 
* Geology under the Planetesimal Hypothesis of Earth-Origin, Bulle- 
tin, G. S. A., vol. XV, pp. 243-266, published June 23. 1904; and Xyi- 
Geologist, vol. xxxiii, pp. 94-116, Feb., 1904. 
f Geologj'. In Two Volumes. Vol. 1. Geologic Processes and their 
Results. New York, Henry Holt and Co., 1904. Pages xix, 654. 
