1893-94.] Prof. Knott and A. Shand on Magnetic Strains. 295 
Note on the Volume Changes which accompany Mag- 
netisation in Nickel Tubes. By Professor C. G, 
Knott, D.Sc., F.R.S.E., and A. Shand, Esq. 
(Read July 2, 1894.) 
In the note which recorded the first observation of the volume 
effects of magnetisation,* the nickel tube experimented with was 
formed by rolling up a sheet of ordinary commercial nickel to the 
convenient size. 
We are now able to record the preliminary results obtained with 
the nickel tubes described in the preceding Note on Magnetic 
Induction. Broadly speaking, the behaviour of the nickel resembles 
the behaviour of certain of the Iron Tubes as described in previous 
communications, f 
The volume changes were measured in exactly the same way as 
formerly described, namely, by the motion of the liquid meniscus 
in a capillary tube which passed through the stopper of the metal 
tube, and was in continuous communication with its interior. The 
decrease of volume in the tube of widest bore (No. I.), when the 
field was 600 and the corresponding average magnetisation 700, was 
so large that it had to be measured with the naked eye. The 
meniscus moved outwards through a distance of 3 centimetres, 
which corresponded to a volume change of 2*4 cubic millimetres. 
This, with a total internal volume of 224*47 cubic centimetres, gives 
a dilatation of fully - 10~b With the tube of intermediate bore 
(No. II.) the volume change in the same field was *63 cubic milli- 
metres, corresponding to a dilatation of a little less than - 10“^ 
Finally, with the tube of narrowest bore (No. III.) the volume 
change in field 600 was *42 cubic millimetres, giving a dilatation of 
- 2*3 X 10~®. These values are all considerably greater than the 
* “On the Effect of Longitudinal Magnetisation on the Interior Yolume of 
Iron and Nickel Tubes. By Professor C. G. Knott {Proc. Roy. Soc. Eclin., 
vol. xviii., 1891). 
t Proc. Roy. Soc. Edin., vol. xix. pp. 85, 2'49, 1892; see also Brit. Ass. 
Reports (Edinburgh Meeting), 1892. 
