Plate I.—Tub Puddling
For wet alluvial prospecting the appliances, besides pick and shovel, are puddling tub ([Fig. 4] and [Pl. I.]), tin dish, and cradle ([Fig. 5] and [Pl. II.]); the latter, a man handy with tools can easily make for himself.
Fig. 5. Sectional Sketch of Cradle.
In sinking, the digger should be careful (1) to avoid making his shaft inconveniently small, and (2) not to waste his energy by sinking a huge “new chum” hole, which usually starts by being about three times too large for the requirements at the surface, but narrows in like a funnel at 10 feet or less. A shaft, say 4 feet by 2 feet 6 inches and sunk plumb, the ends being half rounded, is large enough for all requirements to a considerable depth, though I have seen smart men, when they were in a hurry to reach the drift, get down in a shaft even less in size.
The novice who is trying to follow or to find a deep lead must fully understand that the present bed of the surface river may not, in fact seldom does, indicate the ancient watercourses long since buried either by volcanic or diluvial action, which contain the rich auriferous deposits for which he is seeking; and much judgment and considerable underground exploration are often required to decide on the true course of leads. Only by a careful consideration of all the geological surroundings can an approximate idea be obtained from surface inspection alone; and the whole probable conditions which led to the present contour of the country must be carefully taken into account.
How am I to know true bottom when I see it? asks the inexperienced digger. Well, nothing but long experience and intelligent observation will prevent mistakes at times, particularly in deep ground; but as a general rule, though it may sound paradoxical, you may know the bottom by the top.