giving an increase of 56 per cent. in 30 years.
THE GEOLOGY, BY DR. BOASE.
The geology of this parish is precisely similar to that of the adjacent parish of St. Clether.
The northern part is situated on that range of downs which extends from Launceston to the British Channel. These downs consist principally of varieties of dunstone, which are sometimes felspathic; but in general they are very siliceous, and even quartzoze. They are interesting in an economical point of view, as containing extensive deposits of the ores of manganese. A mine of this substance has been long worked at Letcot in Laneast. The ores occur in a lode or cross course of capel, running north-east and south-west; the lode is about twelve fathoms in width, and is composed of siliceous materials, or rather varieties of compact felspar, in which silex greatly predominates. The ore is arranged throughout the substances of the lode in veins and branches. In the latter form it was originally discovered, not many feet below the surface, and in such abundance that it was obtained at a very trifling cost, for the hardness and tenacity of the capel permitted the ore to be followed in all its ramifications without needing support: and the result of these operations has been to produce a large chasm, with curiously irregular and indented sides.
LANHIDROCK.
HALS.
The manuscript relating to this parish is lost.
TONKIN.