PRESIDENT'S ADDRESS. 15 



whilst the crop is growing underneath. For medical purposes 

 the use of the Rontgen rays has been much improved, and they 

 can now be used to detect early stages of disease in various 

 organs which could not so well be perceived by other means. 

 A non-magnetic ship was last June launched with a view 

 to its making a magnetic survey of the earth, which is expected 

 to take about 15 years. The ship is entirely constructed 

 of non-magnetic materials (with slight necessary exceptions) 

 to facilitate the work of the survey. A magnetic storm of 

 unusual intensity took place on September 25th last, beginning 

 suddenly at 11.43 a.m., and lasting till 8.30 p.m., after which 

 very little disturbance was felt. The oscillation of the needle 

 was large and frequent, and the storm was felt all over the 

 world, but the causes giving rise to it seem uncertain and 

 little understood. There had been on the previous day an 

 extensive disturbance in a large sunspot which might probably 

 have some connection with the terrestrial magnetic storm. 

 The presence of magnetic effects in the sun was proved and 

 can be observed on the earth by means of the spectroscope 

 through a discovery of Zeeman that the lines in the spectrum 

 are duplicated in the presence of a magnetic field in the source 

 of light. From recent observations it seems probable that in 

 places where deposits of petroleum exist, magnetic distur- 

 bances occur in connection with them similar to those caused 

 by deposits of magnetic minerals. This may, if confirmed, 

 be of use in the future in discovering new petroleum deposits. 



CHEMISTRY. 



The statements in the daily papers of the isolation of a small 

 quantity of polonium and of its enormously greater intensity 

 of action than radium must be received with some modifica- 

 tion. Polonium has before been separated, but it is so soon 

 changed into helium and another constituent, probably lead, 

 that its powerful effect is very fleeting and, unless means 

 can be found of producing it in larger quantities, of com- 

 paratively little practical use. In connection with this 



