84 Prof. J. J. Thomson and Mr H. F. Newall, (Feb. 28, 
described, and a comparison was instituted between them, and 
certain forms of extra-floral nectaries. As to the existence of 
intramural glands eg. in Anthurium punctatum the author's 
observations confirmed those of Dalitzch recently published in the 
Botanisches Centralblatt. 
February 28th, 18877. 
Mr TROTTER, PRESIDENT, IN THE CHAIR. 
Mr A. E. H. Love, B.A., St John’s College, was elected a 
Fellow. 
The following Communications were made: 
(1) Haperiments on the magnetization of tron rods, especially 
on the effect of narrow crevasses at right angles to their length. By 
Prof. J. J. THomson, M.A., and H. F. Newatu, M.A. 
IN some experiments on which we have lately been engaged 
it was necessary to use a very strong magnetic field, and in 
measuring its strength we arrived at results which seemed worth 
following up. 
Firstly, we found that we were dealing with magnetic in- 
ductions very much larger than any yet recorded. And secondly, 
we found that the strength of magnetization of an iron rod was 
enormously reduced by simply cutting it in two across the lines of 
force, and putting the cut ends together, separated by a very small 
interval, the reduction rising to between 20 and 40 per cent. when 
the separation was only a small fraction of the diameter of the rod. 
The present note gives the result of some further experiments 
we made on these points. 
Experiments on very strong magnetic fields. 
During last autumn we worked with two large coils each 
having 9 turns of stout copper wire per centimetre of their length, 
the wires being large enough to carry a current of more than 120 
amperes, so that we could produce a magnetic field whose strength 
was as large as 15000¢.G.8. units. The total length of the coils was 
40 cms. ‘hey were separated by an interval of 15 cms. The cur- 
rent was supplied by 10 storage cells, generally in series, and was 
measured by a graded ammeter of Sir William Thomson’s form. 
Iron cores were sometimes made of bundles of soft Swedish iron 
wires held together in a brass tube, sometimes of solid Low Moor 
