Chap. XXVI.] 
MINING V. QUARRYING. 
545 
so that these preliminary workings shall not be carried out to the detri- 
ment of the deposit, and force the technically-trained man, when he cnme? 
on the scene, to spend a considerable portion of his time for some months 
in cleaning up the deposit before he can begin to work it in a systematic 
way. 
In the third section — on the way to work a deposit — I propose to 
indicate roughly the outlines of the methods that it seems to me could be 
adopted with the best advantage when it comes to actually working the 
deposits. I have not gone into any details, both on account of the space 
it would take up and because each deposit is reahy a problem in itself 
with legard to details. This section will, I hope, be of use even to the 
(juahfied miner ; for on CL.ming to a new country he is not likely to be 
able to grasp at once the true structure and mode of occurrence of the 
deposits,and his employers are not as a rule likely to let him sit down 
and find this out in a satisfactory way, unless he can contrive to do 
it in company with a large output of ore, and a small expenditure. The 
figures illustrating this section practically all represent, as regards mode 
of occurrence, deposits that actually exist. 
General Principles for Deciling whether to Miae or Quarry a 
Deposit. 
It may be laid down as an axiom that in working any given mineral 
deposit that method should be chosen that will give the maximum 
profit per ton of ore extracted ; the profit being of course, in the case of 
ores that are exported in a raw condition, the difference between the 
total costs of extracting the ore and putting it on the market, and the 
price it will fetch on that market ; or, in the case of ores that are to be 
smelted or otherwise worked up on the spot, the difference between 
the total costs of extraction, smelting or preparing, and transporting to 
the market, and the price the treated product will fetch when it reaches 
the market. 
In calculating the maximum profit obtainable from a given deposit, 
however, it is necessary to consider the whole of the merchantable ore 
that the deposit may be known to contain, or that it is possible that 
future development may prove it to contain ; that is, it is necessary 
to consider the life of the deposit. 
Now the chief factors that have to be considered in deciding in what 
way to open up a given deposit are the following : — 
(1) The mode of occurrence and structure of the deposit. 
(2) The relation of the deposit to the topography. 
