■192 Proceedings of the Royal Society 
had from time to time published important contributions on the 
geology of his native country, gave to the world a geological 
sketch-map of the Scottish Highlands, based upon the results of 
the labours of several summers spent by him in the north-western 
counties. In this map the crystalline rocks of the Highlands were 
for the first time brought into recognisable geological relationship 
to the other rocks in the British islands. Taken along with the 
different memoirs of which it was an embodiment, it may indeed be 
said to have revolutionised the geology of the northern half of the 
kingdom. Subsequently, after an exploration of the Western and 
Central Highlands by Sir Roderick and myself in company, we 
published in 1861 a first sketch of a new geological map of Scot- 
land, in which the geological structure of the Highlands (as dis- 
tinguished from the mere distribution of different kinds of rock) 
was more definitely traced ; the subdivisions of the old red sand- 
stone and carboniferous formations were put down, and an attempt 
was made to arrange chronologically the different trappean rocks 
of the kingdom. The map was on a very small scale, and was 
necessarily imperfect, and in places erroneous, being offered only 
as a rough outline to show in a graphic form our views of the 
general geological structure of the country. 
The necessity of a detailed investigation of the structure of the 
United Kingdom was recognised by Parliament in 1835, and Sir 
Henry de la Beche, who had at his own charges made some pro- 
gress in a survey of the south-west of England, was empowered 
to employ some assistants, under the Board of Ordnance. His 
small staff was called the Ordnance Geological Survey. Subse- 
quently, in 1845, the great advantages of such a survey having by 
that time been more fully perceived by Government, the number 
of geologists was increased, and the staff transferred from the 
Board of Ordnance to the Board of Works. Since that period the 
geological survey has grown still further, and is now under the 
Department of Science and Art. 
The object of this national Survey is to ascertain in detail the 
geological structure of the country, to publish illustrative maps, 
sections, and descriptive memoirs, and to collect and exhibit 
specimens of the rocks, minerals, and fossils met with in the course 
of the inquiry. The maps on which the field work is conducted 
