This edition has been carefully revised, and, in parts, considerably modified. Thus the Essay on Britain’s Coal Cellars has been added, and two Essays on Government Aid to Science have been removed. I may mention that my views on the subject of the last-named Essays have changed altogether since those Essays were written—certain circumstances which have come under my observation having convinced me that more mischief than advantage would result from any wide scheme for securing Government aid for scientific researches.

Richard A. Proctor.

London: January 1873.