494 Proceedings of the Royal Society 
Berwick ; that its further advance into the central coal-field being 
impossible for want of the Ordnance maps, it was transferred to 
Fife, and spread over the whole of that county and Kinross to 
the Firth of Tay and the confines of Perthshire ; and that the 
maps of the Clydesdale and Stirlingshire coal-field still failing, 
the geological surveying was at last commenced from a new centre 
in the south of Ayrshire during the autumn of the year 1863. 
Since that time the work has advanced steadily northwards and 
eastwards. The large county of Ayr is now surveyed, and the 
maps of it partly published, and partly engraving. Half of Ren- 
frewshire is finished, and the survey of the Clyde coal-field under 
my colleague Mr Hull, is advancing round Glasgow. The work 
of the Survey is now extended across the island from sea to sea, 
and is at present diverging from this completed belt, northwards 
through the rich mineral- fields of Lanarkshire and Stirlingshire, 
and southwards over the counties of Wigtown, Kirkcudbright, Dum- 
fries, and Peebles. 
The field-work is traced upon the six- inch maps of the Ordnance 
Survey, and is then reduced and engraved upon the one-inch maps ; 
the general geological map of the whole kingdom being published 
on the scale of one inch to a mile. But wherever any workable 
minerals occur, in addition to this general map, there are likewise 
issued sheets on the six-inch scale, on which all necessary geologi- 
cal details are inserted. In this manner all coal-fields are pub- 
lished on the large scale, though also included in the general 
geological map on the smaller scale. In order, however, that the 
large amount of detail necessarily accumulated as the Survey 
advances may be made as useful to the public as possible, manuscript 
copies of six-inch maps, which are not to be published, are furnished 
under certain conditions. Landed proprietors, engineers, and others 
thus obtain detailed geological surveys merely at the cost of the 
manual transcription of the original field-maps. 
The area which has now been mapped amounts in all to about 
4100 square miles. Of this area, 2269 square miles have been 
published on the one inch scale. About 800 square miles are now 
in the course of being engraved, and the rest is in progress. Nine 
sheets of the one-inch map have been published, comprising the 
whole or parts of the counties of Edinburgh, Haddington, Linlith- 
