PRACTICAt GEOLOGY. 
341 
Having obtained these data by means of the theodolite, level, and 
chain, the plan was plotted and transferred to a board, which formed 
the base of the model ; this board had upright sides and ends, of 
uniform height, nailed on to it, something like a drawer. 
f h B k 
Spi 
1 
s 
.1 
D 
e g A 
Lign. I. Plan. 
A B, Cross Section. C D, Longitudinal Section. e, f, g, h, i, k, Cross Sections. 
After the sections were plotted to the proper scale, they were trans- 
ferred to sheets of tin and cut out, the counterpart of the section 
forming a template ; by leaving a notch each side to rest on the upright 
sides, this template would be used after the manner of a plasterer's 
mould ; an inspection of the section A B will make this plain. The 
Template. 
Lign. 2., Cross Section on A B. 
surface, by means of these templates, was made exact at each line of 
cross section, and by means of occasional levels, and from memory, the 
portions between were filled in. The tunnel portion was cut out in 
wood, and removeable, for the purpose of showing the position of the 
tunnel, as shown in section A B. 
In taking the longitudinal section from C to D, the outcrop of the 
strata was carefully marked, its dip ascertained with a clinometer, and 
it was afterwards carefully plotted on the section, as shown in the 
