THE value of mine models which show, at a glance, shafts, drives, and ore bodies, as also the extent to which the latter have been worked, must be apparent to all. They convey, in a comprehensive fashion, information which can be brought under observation in no other way, and are therefore of use, not only to the engineer, who is familiar with technical details, but more especially to shareholders_ in a mine who have not had technical training, and, to whom, a series of disconnected plans and sections is frequently bewildering, and who are therefore unable to grasp the salient points in a mining property without other assistance. Considerable use has been made of mine models, and, naturally various forms of construction have been adopted. Among these may be noted "solid glass," "solid wood, "concrete," "glass" and "skeleton" forms. The first three may be dismissed as being either - too heavy or deficient in parts which are essential.