Synthetic corundum for jewel bearings

The paper gives a general description of the manufacturing processes used in the production of rough synthetic corundum and of jewel bearings for electricity meters and other measuring instruments. In Part 1 of the paper typical characteristics are illustrated which are peculiar to natural and synthetic sapphires, to show to what extent the lack of homogeneity of the material can impair its qualities as a bearing. Part 2 deals with the production of synthetic rough sapphires. Reference is made to the method and the apparatus now employed for the synthesis of sapphire. In Part 3 the manufacture and design of jewel bearings is described in a general way, and some special characteristics of corundum are given.