NOTES AND QUERIES. 



improbable fcliey might be arrested and held in a chink of cavity in the gravel. A.8 our 



Correspondent's notice now reads, he would seem to stale they were solidly embedded in 

 the matrix of the grave] at a depth of thirty-five feet, a by no means likely occurrence.— 

 Ed. Gkot,.] 



Production of Copper. — The following extracts are from the ' Lake 

 Superior Miner : ' — 



" In 1830, the total production of the copper mines of the world was 

 about 25,500 ions of metal, and of this amount Great Britain produced 

 13,200, or more than 50 per cent, of the whole, while the United Stales 

 and Canada furnished but 50 tons, or two-tenths of 1 per cent. The Russian 

 Empire then produced nearly 4000 tons, the Austrian Empire 2150 tons, 

 the whole of Asia some 2500 tons. In 1853, twenty-three years later, 

 Britain had only increased her annual product to 14,500 tons, her per- 

 centage of the w hole 1 amount receding to 26; while Chili, in South Ame- 

 rica, \\ hich in 1830 only yielded 200 tons, had raised her product to 14,000 

 tons, or over 25 per cent, of the total production, From that period for- 

 ward to the present time, the copper production of the Chilian mines we 

 believe, exceeded those of any other country, the value of their exports in 

 that metal alone amounting to 4510,760,000 in 1857, while the value of 

 British mine products for the same year was worth about ^9,500,000. 

 The Russians had increased the yield of their mines to 6,500 tons, or llf 

 per cent, of the whole ; the Austrians to 3300 tons, or 6 per cent. ; the 

 whole of Asia only 3000 tons, or 5| per cent. ; while the United States 

 and Canadas raised that year 2000 tons, over 3^ per cent, of the total pro- 

 ducts for that year, which were about 55,700 tons ; Australia and New 

 Zealand produced about 3000 tons ; Cuba, 350 tons; Scandinavia, 2000 

 tons ; the German States, 1450 tons ; and the rest of Europe, exclusive of 

 the countries above named, 1000 tons. 



"During; the past ten years, the mines of Lake Superior have probably 

 increased their production more rapidly than those of any other country, 

 the exports for 1861 — 7500 tons of metal — being about twelve t imes greater 

 than those of 1851. That our ratio of increase in the coming ten years 

 will be as great should not probably be expected, as that would amount to 

 1)0,000 tons ; more by at least 40 per cent, than the present product of the 

 world's mines, Of the 80 miles of copper range cast of us, and 40 to 50 

 miles west, comparatively few mining properties have yet been explored." 



Usefulness of Diamonds. — Many persons suppose that diamonds are 

 only used as jewellery, — for rings and other articles of personal adornment, 

 — and that they are really of no essential value w hat ever in the practical arts. 

 This is a mistaken notion ; they are used for a great number of purposes in 

 the arts. Thus, for cutting the glass of our windows into proper si/.es. no 

 other substance can equal it, and it is exclusively used for this purpose, 

 A natural edge, or point, as it is called, is used for this work, and thousands 

 are annually required in our glass factories. Diamond-points are also 

 employed for engraving on camel ians, amethysts, and other brilliants, and 

 for the liner cuttings on cameos and seals. Being very hard, the diamond 

 it also used in chronometers for the steps of pivots ; and as it possesses 

 high refractive power and little longitudinal aberration, ii has been success- 

 fully employed for the small dee]) lenses of single microscopes. The mag- 

 nifying power of the diamond in proportion to that of plate glass, ground 

 to a similar form, is as eight to three. For drawing minute lines on hard 

 steel and glass, to make micrometers, there is no subst it ute for t he diamond 

 point. The rough diamond is called " bort," and tin 1 " points " used for glass 

 cutting are fragments of the borts. Great care and skill are necc->ar\ in 

 selecting the cutting-points, because the diamond that cuts the glass most 



