1891.] Note on the Density of Alloys of Nickel and Iron. 121 



3. The vaso-motor disturbances are on the same side as the lesion, 

 and consist of vaso-dilation, swelling of the foot, and redness -with 

 rise of temperature of the skin of the foot, but, as compared with the 

 opposite side, fall of temperature in the popliteal space on the side of 

 the lesion, due, no doubt, to paralysis of the muscles. 



4. The degenerations above and below the lesion are limited to the 

 same side when the injury is perfectly unilateral. There are certain 

 facts connected with the degenerations which serve to show the origin 

 and course of certain long and short tract fibres. 



5. Stimulation of the cortex cerebri on both sides some weeks or 

 months after the hemisection had been performed gave, as a rule, 

 results which showed that the block in the spinal cord produced by the 

 hemisection still existed, although there had been a very complete 

 return of associated movements. 



6. In one case ablation of the leg area on the same side as the 

 lesion in the spinal cord was performed many months afterwards. 



II. "The Origin and Progressive Motions of Cyclones in the 

 Western India Region." By W. L. DALLAS. Communi- 

 cated by R. H. SCOTT, F.R.S. Received June 2, 1891. 



III. " Note on the Density of Alloys of Nickel and Iron/' By 

 J. HOPKINSON, F.R.S. Received June 3, 1891. 



In the ' Proceedings of the Royal Society,' December 12, 1889, 

 January 16, 1890, and May 1, 1890, I described certain properties of 

 alloys of nickel and iron containing respectively 22 per cent, and 

 25 per cent, of nickel. These alloys can exist in two states at tempera- 

 tures between 20 or 30 C. below freezing and a temperature of near 

 000 C. After cooling, the alloys are magneti sable, have a lower 

 electric resistance, a higher breaking stress, and lesser elongation ; 

 after heating the alloys are not magnetisable, have a higher electric 

 resistance, a lower breaking stress, and greater elongation. I have 

 now to add another carious property. These alloys are about 2 per 

 cent, less dense when in the magnetisable than when in the non- 

 magiietisable state. Two rings were tested containing respectively 

 25 per cent, and 22 per cent, of nickel with the following results, 

 the densities being given without correction in relation to the density 

 of water at the then temperature : 



