23 September 1966
Vol 153, Issue 3743

About The Cover

Helix made by electroplating tungsten from a molten fluoride solution onto a substrate of tepered copper tubing and then dissolving the copper with nitric acid. The thickness of the wall of the central tube, in spite of the electrical shielding by the outer helix, demonstrates the exceptional ``throwing power'' of the process. Because tungsten is brittle, machining such an object would be extremely difficult. See page 1475. [S. Senderoff and G. W. Mellors, Union Carbide Corporation]