ISOSTASY, A REJOINDER TO THE ARTICLE BY 
HARMON LEWIS 
JOHN F. HAYFORD 
Director, College of Engineering, Northwestern University 
In the Journal of Geology, Vol. XIX, No. 7, October-November, 
IQII, pp. 603-26, there was published an article by Mr. Harmon 
Lewis, entitled ‘‘The Theory of lsostasy,”’ which is a direct attack 
on three publications by John F. Hayford, namely, The Figure of 
the Earth and Isostasy from Measurements in the United States, 
Supplementary Investigation in 1909 of the Figure of the Earth and 
Isostasy, both published by the Coast and Geodetic Survey, and 
“The Relations of Isostasy to Geodesy, Geophysics and Geology”’ 
published in Science, pp. 199-208, February 10, r911. The attack 
is direct and positive. Hence this rejoinder is written in a similar 
manner. The critic may not reasonably object to having his 
article treated in the manner in which he has treated the publica- 
tions criticized. 
Mr. Lewis claims in his article that Hayford has made a funda- 
mental error in his geodetic investigation, an error in method 
which vitiates all the conclusions reached. The greater portion 
of the article is devoted to setting forth this alleged error of method 
and its consequences. A few pages in the article are devoted to 
the proposition that since the theory of isostasy does not explain 
all of the geological facts which have been observed, isostasy 
probably does not exist. 
Hayford believes that Mr. Lewis has in his article, probably 
unintentionally, overstated even his own extreme views. Haytord - 
is certain that the alleged fundamental error in method in the 
geodetic investigation, which Lewis sets forth, is not an error 
and, moreover, that if Lewis had followed his own line of thought 
to its logical conclusion, he would have convinced himself that 
no error had been made. The forms of statement used by Mr. 
Lewis lead one to think that he has some positive basis for other 
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