520 Proceedings of Royal Society of Edinburgh. [sess. 
widening bore, — the tubes being, in fact, produced by successive 
borings from the same original bar. 
Broadly speaking, the tendency in the case of the first set of 
iron and steel tubes was to show decrease of volume in low fields 
and increase of volume in moderate and high fields ; but in the 
last set of iron tubes studied, decrease of volume was obtained in 
high fields also. 
The nickel tubes all agreed in showing large diminution of 
volume in most fields, with slight increase of volume in very low 
fields. 
As a rule, the wider the bore of the tube the greater the maximum 
change of volume. There are, however, curious deviations from 
this rule, which are shown in Part II. to be due to the fact that 
the volume change is a differential effect, being the resultant of a 
change of length in the direction of magnetisation, and a change 
of area transverse thereto. These longitudinal and transverse 
dilatations tend to be of opposite sign, and experience interesting 
variations as the bore of the tube is made wider and wider. 
The volume changes measured in these experiments are much 
greater than those shown by iron or nickel rods, and indicate a 
very complex condition of strain, the investigation of which seems 
to be beyond our present powers of analysis. 
For these novel and highly interesting results, obtained by 
experimental investigation carried on through six years with re- 
markable ability and perseverance, the Keith Prize, for the period 
1893-5, has been awarded by the Council to Dr Cargill G. Knott. 
The Makdougall-Brisbane Prize for 1894-6 was presented to 
Professor John G. M‘Ivendrick, for numerous Physiological papers, 
especially in connection with Sound, many of which have appeared 
in the Society’s publications. 
The President, on presenting the Prize, said : — 
During the last four years Professor M £ Kendrick has devoted 
himself with persevering zeal and enthusiasm to researches in the 
physiological and dynamical actions concerned in the perception of 
sound. The admirable model with which he explained and 
demonstrated by actual working, a mechanism in accordance with 
