232 



Roijal Society : — 



The wave transit in these experiments was made partly in slate 

 rocks and partly in quartz formations, which, though lithologically 

 and geologically distinct, are nearly identical in wave propagative 

 power (as this author has shown by a train of special experiments 

 at the conclusion of the paper), differing not more than in the ratio 

 of 0*5 76 for the slate to 0*558 for the quartz. The author concludes 

 by pointing out several deductions having interest to general physics, 

 and some of the special relations of the results to Seismology and 

 Physical Geology. 



'* On the Cutaneous Sensibility of the Hand and Foot in different 

 parts of the Surface, as tested by the Continuous Galvanic Current." 

 By Harry Lobb, Esq. 



"Experiments and Observations on the Structure and Function of 

 the Stomach in the Vertebrate Class." By William Brinton, M.D. 



" Notes of Researches on the Intimate Structure of the Brain." — 

 Second Series. By J. Lockhart Clarke, Esq., F.R.S. 



"On the Influence of Atmospheric Pressure upon some of the 

 Phenomena of Combustion." By Dr. Edward Frankland, F.R.S. 



The author has concluded his experiments upon this subject ; and, 

 in addition to the details of the results which have already been 

 briefly mentioned in the Philosophical Magazine, S. 4. vol. xxii. p. 

 549, communicates the following : — 



Although the rate of burning of candles and other similar com- 

 bustibles, whose flames depend upon the volatilization and ignition 

 of combustible matter in contact with atmospheric air, is not per- 

 ceptibly affected by the pressure of the supporting medium, yet this 

 is not true of all combustibles. The rate of burning of self-support- 

 ing combustibles, like the time-fuses of shells, depends essentially 

 upon the pressure of the medium in which they are deflagrated. 

 Attention was first called to this fact by Quartermaster Mitchell *, 

 who found that the fuses of shells burnt longer at elevated stations 

 than when ignited near the level of the sea. The results of the 

 author's experiments with six-inch or thirty-seconds fuses burnt in 

 artificially rarefied air are embodied in the following Table : — 



Average pressure 



of air in inches 



of mercury. 



Average time 

 of deflagra- 

 tion of six- 

 inch fuse. 



Increase of 



time of burning 



over preceding 



observation. 



Reduction of 

 pressure cor- 

 responding 

 with increase 

 of time. 



Increase of 



time for each 



diminution of 



one inch 



pressure. 





Seconds. 



Seconds. 



Inches. 



Seconds. 



30-40 



30-33 









28-25 



32-25 



1-92 



2-15 



•893 



25-70 



34-75 



2-50 



2-55 



•980 



22-45 



37-75 



3-00 



3-25 



•925 



19-65 



41-50 



3-75 



2-80 



1-339 



15-95 



45-50 



4-00 



3-70 



1-081 



* Phil. Mag. S. 4. vol. x. p. 48. 



