Page:Popular Science Monthly Volume 82.djvu/525

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THE

POPULAR SCIENCE

MONTHLY


JUNE, 1913




SOME FURTHER APPLICATIONS OF THE METHOD OF POSITIVE RAYS[1]

Professor SIR J. J. THOMSON, O.M., LL.D. D.Sc, F.R.S.

CAVENDISH PROFESSOR OF EXPERIMENTAL PHYSICS, CAMBRIDGE, AND PROFESSOR OF NATURAL PHILOSOPHY, ROYAL INSTITUTION

THE method to which I shall refer this evening is the one I described in a lecture I gave here two years ago. The nature of the method may be understood from the diagram given in Fig. 1. A is a vessel containing the gases at a very low pressure; an electric discharge is sent through these gases, passing from the anode to the cathode C.

Fig. 1.

The positively electrified particles move with great velocity towards the cathode; some of them pass through a small hole in the center, and emerge on the other side as a fine pencil of positively electrified par-

  1. Address before the Royal Institution of Great Britain, Friday, January 17, 1913.