viii Proceedings. {^November 12th, igi 2. 



Ordinary Meeting, November 12th, 19 12. 



The President, Professor Y. E. Weiss, D.Sc, F.L.S., 



in the Chair. 



A vote of thanks was given to the donors of the books upon 

 the table. These included : •' A Monograph of the Mycetozoa...^'' 

 by A. and G. Lister, 2nd ed. (8vo., London, 191 1), and "-A 

 Revision of the Ichneiimonidac" by Claude Morley (8vo., London, 

 191 2), presented by the Trustees of the British Museum; and 

 ''Flora capensis,'' vol. 5, sect, iii., pt. i., by Sir W. T. Thiselton- 

 Dyer (8vo., London, 1912), purchased. 



Professor S. J- Hickson, F.R.S., exhibited a pearl alleged 

 to have been found in a Nautilus. The pearl, which is 

 irregularly pear-shaped, Aveighs 27-5 grains, and was presented 

 to Professor Hickson by a Dutch magistrate in North Celebes. 



A paper by Dr. Hknry Wii.dI', F.R.S., was read "On 

 Search-Lights and the 'Titanic' Disaster." 



This paper is printed in full in the Alemoirs. 



Mr. H. G. J. MosELKY, B.A., read a paper entitled 

 " Radium as a means of obtaining High Potentials." 

 He stated that a radio-active substance which emits /(3-rays 

 should, when insulated, continue to gain a positive charge until 

 a potential of the order of a million volts is reached. Only the 

 fastest /3-rays should then be able to escape. Experiments have 

 been made to test this point. A small bulb containing radium 

 emanation was supported by a quartz rod in the centre of an 

 exhausted flask. A disk suspended from a quartz spring in the 

 neck of the flask formed a simple attracted disk electrometer. 

 It was found that a bulb of diameter 9 n.ni. reached a potential 

 of 160,000 volts in the course of a few minutes. A sudden 

 discharge then took plnce through the residual L:as in the flask, 

 although great care had been taken in obtainmg the vacuum. 

 A bulb of diameter 5 cm. charged up much more slowly : in 



