138 ORIGIN AND DEVKLOPMBNT OF ORE-DEPOSITS. 



ores in the West in England."* Mr. Henwood uses the word 

 "lode" in the practical miner's sense, that is, he includes the 

 ■whole of the workable band of mineralized country by the side 

 of the fissure as well as the actual fissure-filling, whatever may 

 belts nature, whether ore-leader, flucan, vein-stone, breccia, or 

 capel. In this sense a lode may be defined as a metalliferous 

 band or deposit occupying or bounding a fissure of inconsiderable 

 thickness as compared with its length (rarely more than y^o^th 

 and often less than looo o^-^) ^^^ extending to a great or unknown 

 depth. Using the term then in this sense, Mr. Henwood gives 

 in a number of useful tables the results of his very numerous 

 observations on the lodes of Cornwall and Devon as regards 

 direction, inclination, width, and principal contents. Referring 

 my readers to the original "address" for numerous and 

 important details, I merely extract for use in this enquiry the 

 following particulars. 



1. The mean directions of the lodes in the different 

 " districts " of the West of England are : 



Camborne, &c., 20° N. of E. 



The average bearing throughout being about 5° N. of E., "a 

 range not materially different from that of the granite which 

 appears at intervals between Dartmoor and the Lands End "f 



*Presideiitial Address, 1871, Journal Royal Institution of Cornwall, xiii. 

 In a practical sense this dictum is unquestionable, although the present essay will 

 shew that even from this point of view the stockworks, and other "irregular 

 deposits" are worthy of somewhat more consideration than was given to them by our 

 excellent President, while from the theoretical and scientific side they are of the 

 highest possible importance. 



flbid, p. XVI. This generalization is no doubt an important one — yet it may 

 probably lead to serious misconceptions, for, Ist as to the mean bearing for the 

 whole county, it is manifestly of little use to make up an average from such 

 incongruous elements as appear in the table given. 2nd, an equally important 

 criticism of Mr. Kenwood's mean directions for individual lodes, from which his 

 mean directions for the different "districts" were derived, was made many years 

 since by Captain Charles Thomas in the following words—" Mr. W. Jory 

 Henwood in his report of the two hundred mines in Cornwall and Devon has 



