540 Dr. FE. Naumann—WMagnetism and Earth Structure. 
especially as regards the declination.” ‘Then, almost in the same 
breath, he searches for the causes of observed irregularities, and 
finds them in the distribution of volcanic rocks. Little or no 
attention seems to have been paid to the most interesting dis- 
turbance that must have existed at Ino’s time (at the beginning of 
this century), and which Mr. Sekino’s observations show to still 
exist, nor was the peculiar phenomenon exhibited by the magnetic 
block on the summit Morigoski examined; this is all the more 
surprising, as two stations of Dr. Knott’s survey lie in the immediate 
neighbourhood of these remarkable places. 
It may appear that I am dealing too minutely with Dr. Knuott’s 
paper, but I think the criticisms are justified by the interests of 
science. It is by no means satisfactory to see that so many fellow- 
workers on the field of science cannot build without pulling down, 
for it should be the serious duty of every one to advance from 
wherever a safe footing has been attained. Earnest and honest 
labour deserves respect rather than condemnation. Unfortunately 
it is usual for critics to introduce their subject with an exhaustive 
survey of all its faults, instead of commending its merits. The 
greater the effort made to ascertain its merits and appreciate them, 
the easier will it be to use existing knowledge as a foundation for 
future progress, and those who neglect this duty tend to check 
rather than promote the advancement of science. 
Dr. Knott does not appear to be acquainted with my pamphlet, 
for if he had read it he need not have devoted so many pages to the 
rather antiquated chapter on Rock Magnetism ; and if his knowledge 
of the Geology of Japan was more profound, his opinion as to the 
causes of irregularities being entirely superficial would be modified. 
In his paper we are taught that “the volcanic nature of the rocks 
is more than enough to account for all irregularities.’ Why ? 
Perhaps because volcanic rocks are known to contain magnetic iron 
ore? If so, Dr. Knott should have remembered that the volcanic 
tuffs, widely distributed over the country, consist of the same 
materials as so-called volcanic rocks. In addition, as proved in my 
memoir, rock magnetism does not influence the curve-systems, nor 
do the values of the constants depend on the nature of the rocks 
developed in the neighbourhood. 
In considering such questions the following points are important : 
how the earth’s crust is composed of masses of rocks; how deep the 
fissures penetrate into the earth and establish connection with the 
interior of the globe; whether these fissures are closed or not, ete. 
In the locality under discussion there are two enormous fissures, 
intimately connected with the development of the great earth-wave 
whose crest appears as the Japanese island chain. One of these is 
longitudinal, and divides the whole mountain-range into inner and 
outer zones ; the other is transversal, and divides the chain into two 
parts which stretch towards the north-north-east and west-south- 
west respectively. The transversal fissure is indicated by the Fossa 
Magna, and the longitudinal one curves back towards the Sea of 
Japan, where it intersects the former (see Plate XVII.). Enormous 
