IN the early stages of opening up a mine, when there is some uncertainty as to its future career, necessitating caution in laying out works of a permanent character, the want is often felt of an assay furnace, easily built and easy of transportation, should the "mine" prove to be "no mine." Again, cases occur in which parties buy the right to treat comparatively small heaps of tailings, treat them, and then shift their plant to other localities. -Under these circumstances it is necessary to restrict the plant to the barest necessaries, to suit, so to speak, the nomadic character of the work.