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PEACTICAL GEOLOGY. 
ON THE PRACTICAL APPLICATION OF GEOLOGY TO CERTAIN DEPARTMENTS OF 
RAILWAY-ENGINEERING, WITH A DESCRIPTION OF A METHOD OF MAKING 
WORKING- MODELS. 
By T. E. Ccrley, C.E., E.G.S., A. Ins. C.E. 
Sir, — Although the following is not purely geological, perhaps you 
will not consider it inadmissible in your journal, as it tends to illustrate 
a system of making geological models and sections of large tracts of 
country for engineering-purposes. 
It is a well-known fact that hundreds of thousands of pounds might 
have been saved in the construction of our railways, if time had been 
taken to study in detail the geology of the country traversed, instead, 
as was the case in 1844 and 45, of laying down the projected lines 
on the ordnance map from the nearest turnpike-road, when travelling 
at the rate of eight or ten miles an hour, or even, as was very often 
done, in the office, without seeing the ground at all. Innumerable 
slips, wet cuttings, wet tunnels, kc, might have been avoided by a 
slight diversion, based on geological knowledge. For instance, take 
a line running along a narrow gorge of some small river or stream in 
a northerly direction, and suppose the rocks on each side to have the 
same dip from west to east. Now, if the railway be made on the west 
side, in side-cutting it is obvious there will be slips, if the angle of 
inclination of the strata is greater than the angle of repose ; and cer- 
tain that the cutting will be a wet one, requiring a flat slope, and in- 
volving expensive drainage ; whereas, if the railway was projected on 
the opposite or east side of the gorge, it is highly probable that the 
cutting would be perfectly dry, and that the slope would stand nearly 
perpendicular. 
In 1843, the Leeds and Thirsk Railway Company projected a tunnel 
through the Bramhope Hills, from which issue the springs and streams 
that partly supply the Eccup lleservoir, belonging to the Leeds 
Water "Works Company. In 184.5, Mr. Seather, of Leeds, the engineer 
for that company, instructed me to make a model of the portion of 
country lying between Eccup Reservoir and Otley, for the purpose of 
illustrating the geological and engineering evidence required in 
opposing the railway-bill before the Committees of both Houses of Par- 
liament ; and by which we succeeded in getting a clause introduced 
for compensating the \yater Company for any loss of water they should 
sustain through the railway-works. 
The following is the plan I adopted in making the model, which 
embraced about twenty square-miles of country. In the first place, I 
made a ground-plan showing the principal roads, streams, springs, &c. ; 
I next took cross sections of the range of hills, twenty chains apart, and 
parallel to each other ; also, a longitudinal section through the centre, 
at right angles to the line of strike of the rocks, as well as to the cross 
sections. 
