94 SECTIONAL ADDRESSES. 
adoption of artificial stones devoid of the qualities which undermine the 
power of resistance of natural stones ; at the same time more control over 
colour and shaping may be obtained. 
Roads.—Closely akin to the subject of building materials comes that 
of stones used for flagging, paving, and metalling of roads, to the provision 
and study of which the geologist has already very largely contributed. 
New problems are daily introduced as road traffic becomes heavier and 
as roads are required to be freer from dust and vibration. Already many 
waste products have come into valuable utilisation, and a wide range of 
road metals which can be called upon for these purposes exists in almost 
every country. 
In the siting of roads, railways, and canals, however, geology could 
render much more useful service than it has yet been called upon to give. 
The routes that are cheapest to make are by no means the cheapest to 
maintain, and the geological survey of routes would very often suggest 
slight deviations which would be more economical in the end than when 
the shortest route compatible with the gradients is taken. 
The princes of road-makers in the old world, the Romans, were perhaps 
too heroic in their dealing with gradients, but they exercised quite remark- 
able skill in choosing such directions as to secure the least formidable 
slopes consistent with the general design of their routes. Their roads 
were, however, constructed primarily for strategic purposes and secondarily 
for transport, and it was necessary to sacrifice something. On the other 
hand, the constructors of the coach-roads were, perhaps, too sensitive to 
the psychology of their horses and the limitations of their vehicles, and 
their roads are not ideal for present-day traffic. Some compromise seems 
to be required between the two methods, and not the method of the 
Roman tempered by the cuttings and tunnels of the railway engineer. Now 
that we have a vehicle that rejoices in a hill, whether for or against 
it, and for the first time have a means for hill-climbing at speed, it is a pity 
to flatten down gradients too much; and though it is legitimate and even 
necessary toremove dangerous crossings and curves, itshould be remembered 
that an everlasting straight vista is as exasperating to a driver as it is 
heart-breaking to a horse. And if roads of this most desirable type are 
to be satisfactorily and cheaply maintained, it will be more than ever 
necessary to study routes in relation to the rocks that are traversed and 
the water contained in them. 
Something of what has been said with reference to roads applies with 
equal force to other engineering undertakings, railways and canals, 
harbour-works, bridges, and large and heavy buildings, particularly those 
intended to stand for centuries. The general success of such works is 
ample testimony to the knowledge and skill expended upon them by 
engineers and architects, as well as to the elastic toleration of sites so 
heavily taxed ; and one is tempted to believe that a much larger amount 
of study has been given to geological questions in these cases than is 
usually admitted. 
Water.—Of all engineering questions, that most closely involved with 
geological science is probably water-supply. So far as underground 
water is concerned, geologists and engineers working together have 
amassed a volume of fact and principle which has not yet been completely 
codified and rendered accessible. An unexpectedly large proportion of 
