EXTENDED application of the principles upon which the cradle was based, led first to sluice boxes, then to ground-sluicing and to elevating and sluicing, in all of which water is made to do a large amount of the work. In order to obtain supplies of water with sufficient force to break up ! soil, many dams were constructed, and the water was led many miles in open ‘races,’ or in n pipes, to the miners’ claims, form of mining which required considerable (ital and which, therefore, was usually carried : by companies, was dredging. By means of dredges, which were first used for winning gold Mew Zealand, wash-dirt was obtained from the Is of large rivers. The earliest ‘ spoon-dredges’ re employed in 1863 and for a time they won considerable amount of gold with very simple alliances. Five years later the bucket type of dredge was introduced, and this, in various improved forms, has been used ever since, important changes being the introduction of steam dredges about 1882 and the accidental but very profitable discovery, at the very end of the century, that often re were rich gold-bearing deposits concealed beneath a hard layer which was apparently the torn of the river bed.

In the boom period of dredging, about 1900, dent dredges secured as much as 1,000 ounces of gold in one week’s working. These rich returns caused feverish speculation, large sums being made and lost by people who never saw a dredge. The disappointments suffered by many even in the boom period, and the exhaustion of the richest deposits caused a slackening of interest in dredging until after the War, when the increased price of gold revived the hopes of investors by ensuring profitable returns from only moderately rich work­ings.

The dredging companies, using modern machinery and methods, including geophysical surveys and prospecting by boring, though not surrounded with the romantic interest that attaches to the individual digger wresting Nature’s riches from her, nevertheless make important contributions to the gold production of the country.