INDUSTRIES 



of local mines. Mr. Thomas died in 1861, 

 leaving the works to his two sons, James and 

 Edwin Thomas. After the death in 1880 of 

 the former, who survived his brother, the works 

 were carried on by the beneficiaries until 1884, 

 when they were purchased by Mr. Martyn of 

 St. Austell, for the purpose of starting them under 

 a limited liability company. The present com- 

 pany was accordingly formed, and by them the 

 works were greatly enlarged and improved, 

 and a bridge-building department added, with 

 modern appliances and tools. Owing, however, 

 to the heavy carriage expenses of sending bridges 

 long distances this part of the business was not 

 remunerative and was abandoned, the plant being 

 utilized for boiler-making. A good business is 

 done in large Lancashire and Cornish boilers for 

 the china clay works and local mines, and for 

 Plymouth. 



The works are well equipped, and are capable 

 of dealing with the entire engineering require- 

 ments of the mines, and more particularly of the 

 china clay industry. Mining machinery of every 

 description is manufactured, besides bridges, roofs, 

 girders, tanks and other constructional iron work. 



Bartle's Foundry was established about the 

 year 1860 by Messrs. Bartle, William Dunkin, 

 Thomas Henry Tregoning and Joseph Lugg, 

 at Cam Brea, the centre of a busy and populous 



district, and in the midst of mines for the 

 purpose of supplying the latter with general 

 foundry and iron work. 



By dint of hard work a good business was 

 formed. After a few years Mr. Lugg retired, 

 and the concern was carried on by the remaining 

 partners until the year 1884 when, owing to 

 disagreement, it was suspended and was offered 

 for sale. Mr. F. Bartle, one of the founders, 

 became the purchaser, and with his sons, Mr. 

 Charles D. Bartle and Mr. William Bartle, who 

 returned from America for the purpose, has 

 carried on the business ever since under the 

 title of F. Bartle & Sons. 



The works have been enlarged, and the business 

 considerably developed, being well known in the 

 mining world. The persons employed number 

 from 70 to 100. 



The manufactures include the Murdoch Rock 

 Drill and tube mills. The patent of the latter 

 was held by this firm, and was formerly known 

 as the Barrel Pulverizer. Michell and Tregon- 

 ing's Pulverizers are also made ; large numbers 

 of both kinds are working in Cornwall and other 

 places. The firm also make a speciality of 

 slime-dressing machinery, and have just patented 

 an improved Slime Concentrator. They are also 

 well-known makers of double faggoted iron, large 

 quantities of which they send to South Africa. 



CHINA CLAY 



No account of Cornish Industries can claim 

 to be complete which does not include a sketch, 

 however brief, of that industry which is, and has 

 always been, since its inception about the middle 

 of the eighteenth century, the most uniformly 

 progressive of them all. 



The causes, mechanical and chemical, which 

 have led to the formation of china clay are well 

 known. On the one hand, variations of tempera- 

 ture and the congelation and consequent expansion 

 of water within the minute pores of granite rock ; 

 on the other,the concurrent chemical action of car- 

 bonic acid, robbing the felspar and mica contained 

 in the granite of their potash ; these are com- 

 monly held to have been the chief causes of that 

 process of disintegration by which china clay, 

 or kaolin, has been formed. 1 



Wherever in Cornwall there is a granite 

 formation the Carnmenellis district excepted 

 china clay has been formed. West Penwith, 

 Breage, the moors north of Bodmin, all contain 

 deposits ; but by far the most considerable as 

 well as the most valuable clay beds are those of 

 the Hensbarrow district which embraces large 

 portions of the parishes of St. Austell, St. Blazey, 



1 It should be mentioned that a very competent 

 writer, Robert Hunt, F.R.S., considers china clay to 

 be granite which has never properly been formed, 

 rather than granite which has undergone decomposition, 

 See British Mining, p. 196. 



Luxulian, Roche, St. Denys, St. Enoder and 

 St. Stephen in Brannel. 



About the middle of the eighteenth century the 

 presence of this valuable product became known 

 to the potter. Mr. William Cookworthy, who 

 had established a pottery in Plymouth in 1733, 

 obtained in conjunction with Lord Camelford a 

 patent for the use of china clay in 1768. In 

 1813 there were seven clay beds being worked 

 in the Hensbarrow district, the largest of 

 which produced about 300 tons of clay per 

 annum. 2 The amount of china stone shipped 

 at Charlestown in 1816-17 was 2 > Z 35 tons > 

 and of china clay 1,775 tons. 3 Since that 

 time the returns have steadily increased, as will 

 be seen from the following table 4 : 



Year. China Clay. China Stone. Total. 



1816 . 1,775 . 2,135 . 3,910" 



1826 . 7,538 . 5,252 . 12,790 3 



1838 . 13,440 . 7,344 . 20,784 3 



1855 . 60,188 . 19,961 . 80,149* 



1864 . 95,73 21,570 . 117,300* 



1874 . 150,500 . 42,500 . 193,000* 



1894 . . . 386,648* 



1903 . 490,881 . 53,680 . 544,561* 



i94 5i5,45i 66,994 . 582,445* 



2 Annals of Philosophy, vol. ii, p. 475. 



3 Trans, of the Geol. Soc. ofCornio. 



4 Mineral Statistics, published by the Home 

 Department. 



577 



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