1887] Methods of Instruction in General Geology. 621 
For a geologist familiar with the general subject, and as a 
book of information arranged for ready reference, this is as good 
an arrangement as could be desired. But when the science is 
presented for the first time to the student, is this the order in 
which he must grasp the details of the subject for clear compre- 
hension? I think not. 
And why is it unnatural? Because the student is asked to take 
the results of an analysis before he is presented with the concep- 
tion of the thing analyzed. He is led to form a synthetic concep- 
tion of the objects studied, built up of definitions, rather than by 
analysis to increase his knowledge of the object by narng it in 
new relations. 
Rocks are at first parts of the earth, and among themselves 
they first differ in their physical relations of position, structure, 
form, and composition. The chemical and mineral properties are 
secondary in order of analysis; and the microscopic appearances 
presented by separate mineral species constitute a tertiary set of 
characters. 
The teacher should have regard to this order of acquisition, 
although, after having named and briefly described the terms, 
they may become for his purposes mere definitive terms with 
-which to describe the more comprehensive laws of the earth’s 
formation. 
For this. reason ‘there is propriety in uniting physiographic, 
structural, and dynamical geology as a first division of the 
general treatment of geology, following with the stratigraphical 
and palzontological part as a second division, 
This plan, substantially, is followed in several of the more 
widely used text-books, as Phillip’s, Credner’s, Geikie’s, Le- 
conte’s, and others. 
ae determining the order of presentation of the facts for par- 
ticular cases, I examine the order in which the facts naturally 
develop in the process of investigation. As a general statement 
of what this order is, I find it to be from the more conspicuous, 
the more easily grasped, and the simpler, to the less evident, the 
intricate, and the fundamental. This same regard to the order 
of acquisition of ideas is applicable to the methods of illustration, 
Every teacher of natural history has more or less use for 
. diagrams, but I have thought that blackboard sketches, although 
Ee = made while the sapanotion is. going on, are inc, mpe : 
3 —NO. 7 42 
