24 Messrs. W. E. Wilson and P. L. Gray. On the 



DESCRIPTION OF DIAGRAMS. 



The continuous lines represent the curves of the variations in level of the brain 

 surface produced by pressure and otherwise. The dotted lines represent the height 

 of the blood pressure. 



The times in which compression and recoil are measured are noted above the 

 diagrams in seconds. The enumeration of seconds always commences afresh at the 

 point at which the weight is removed. 



Fig. 3. 50 grams applied for 1 minute. This diagram shows typically the 



characters of the excursion and recoil. 



Fig. 4. 50 grams applied for 1 minute. Between experiments a and 5 the brain 

 was allowed to entirely recover its volume, and the animal was then 

 bled to the extent of 150 c.c. This procedure caused a fall of the brain 

 surface to 3'4. 



Fig. 5. Shows a typical curve when 50 grams are applied for 4 seconds only. 

 Fig. 6. The curves as far as * show the concurrent variations of brain surface 

 and blood pressure under the influence of amyl nitrite. At * experi- 

 ment a was performed. Between experiments a and b the effect of the 

 amyl nitrite was allowed to wear off completely. 20 grams was the 

 weight employed. 

 Fig. 7. (a) was an experiment upon the normal brain. 



(6) was performed after administration of amyl nitrite. Weight 



= 50 grams. 

 Fig. 8. (a) performed with a cannula in one superior cerebral vein. 



(J) performed with the opposite superior cerebral also blocked. Weight 



= 50 grams. 

 Fig. 9. (a) performed on the normal brain. 



(b) performed with both external and both internal jugulars clamped. 



Weight = 50 grams. 

 Fig. 10. 50 grams applied for 6 minutes. Etherisation diminished at * with a 



consequent rise of blood pressure. 



Fig. 11. 50 grams applied for 30 seconds to a brain which had undergone con- 

 siderable previous compression. Etherisation diminished at *. Trachea 

 clamped at 0. 



" On the Temperature of the Carbons of the Electric Arc - f 

 with a Note on the Temperature of the Sun. Experi- 

 ments made at Daramona, Streete, Co. Westmeath." By 

 W. E. WILSON, M.R.I.A.,' and P. L. GRAY, B.Sc., A.R.C.S. 

 Communicated by G. JOHNSTONE STONEY, F.R.S. Received 

 November 14, Read November 22, 1894. 



The temperature of the positive pole of the electric arc, which is 

 now generally believed to be the boiling point of carbon, is usually 

 taken, on the authority of Yiolle,* as approximately equal to 3500 C. 

 Violle's method of determining it was as follows : The carbons of 

 the arc were placed horizontally, and the positive pole was so arranged 



* Violle, ' Jour, de Phys.,' 3rd Series, vol. 2, 1893, p. 545. 



