Note * — Chapter XVI · OUT CAROLLING.

The water is pumped from the Cornish tin-mines into the numerous little streams which, after a short course, run into the sea. This water carries with it a large proportion of tin, and to prevent this tin running into the sea and being lost, what are called "stream-works" are erected all along the streams. These are nothing but gigantic filters, through which every drop of water is compelled to pass, leaving some of its metallic treasure behind it as it goes. It is a curious fact that, although these works are very numerous, one nearest to the sea and farthest from the mine secures as large a share of the metal as one farthest from the sea and nearest to the mine—the water having passed through a dozen works upon the way, all of which have taken as much as possible of its burden from it.