1864. | Mining, Mineralogy, and Metallurgy. 187 
and fine adjustment, and has the additional advantage of a magnetic 
stage, in the cross-bar (h) of which is a groove, in order that the 
observer may enjoy the luxury of applying a Maltwood’s finder, as in 
large instruments possessing movable stages.* Beneath the stage is 
seen the polariser (p), fitted into the circular diaphragm. 
The double mirror (m) possesses a triple joint, so that it can be 
applied obliquely in all directions. Indeed, as we before said, it is 
difficult to see how an instrument could be devised of a more simple, 
and, at the same time, so perfect construction at the price. 
Having now given our readers an insight into the most important 
improvements that have been recently made in the construction of 
the instrument, we purpose in our next Number introducing to their 
notice, the various works on the microscope, and its mode of appli- 
cation. 
VII. MINING, MINERALOGY, AND METALLURGY. 
Tue Mining operations of these islands may be regarded as amongst the 
most important of our industries, taxing—as they do, to the utmost— 
the powers of man’s endurance, and the resources of engineering 
science ; requiring the boldest expenditure of an enormous capital, and 
adding nearly thirty millions sterling to our national wealth. Hidden 
in our rocks is the “ hoarded treasure,” but man, the magician with 
the wand of industry, brings it forth to-day and converts the valueless 
ores into valuable metals, which minister in a thousand forms to the 
necessities of human existence. 
The subterranean explorations now in active progress in this 
country, claim the labours of above 300,000 Miners, independently of 
men, boysand women, employed at the surface. They task the powers 
of thousands of steam-engines in pumping the waters from the depths ; 
in drawing the minerals from the mines; in lowering and raising the 
men; and in restoring pure air to those dark recesses in which the 
atmosphere is rapidly suffering deterioration from several causes. 
At the present time there are upwards of 3,000 collieries, and not 
less than 1,000 metalliferous mines at work in the United Kingdom. 
The produce of these—in the more important minerals only— during 
the last two years, has been as follows :-— 
1861. 1862. 
Tons, Tons. 
CoaLs . . 85,635,214 ‘5 - $1,638,338 
Tron ORE . iezlovols * - 7,562,240 
CopPpPrER : 5 231,487 5 : 224,171 
RIN’ == . 3 11,640 ° “ 14,127 
LEap 5 2 90,696 < : 95,311 
ZINC : és 15,770 2 ‘ TAIT 
PyYRITES . = 125,135 ‘ 98,433 
* Maltwood’s finder can be obtained at Smith, Beck, and Becks. 
+ These, and all the statistical returns given, are taken from the ‘ Mineral 
Statistics of the United Kingdom,’ by Robert Hunt, F.R.S., which are published 
annually by order of the Lords Commissioners of Her Majesty’s Treasury. 
