1892.] to produce a Spark in Air at different Pressures. 113 



FIG. 8. 



whole distance, and that portion which lies close to the horizontal 

 (or spark-length) axis refers to the low pressures of Part II, in 

 measuring which a small error might again make considerable differ- 

 ence. These portions apart, it will be noticed that the more curved 

 portion of the curve is a fairly close approximation to a rectangular 

 hyperbola, as may be seen from the following table : 



The portion s of the curve more distant from the origin show con- 

 siderable divergence from the hyperbola, though perhaps, as has been 

 pointed out, not more than might be due to errors of observation. 



VOL. LII. I 



