1(1-1. THK I'^MORESS OF SCIK\ n 



and not at another and which would therefore 

 be a real epicurean chance-world ? 



For myself, I must confess that I find the air of 

 this region of speculation too rarefied for my con- 

 stitution, and I am disposed to take refuge in 

 " ignoramus et ignorabimus." 



The execution of my further task, the indica- 

 tion of the most important achievements in the 

 several branches of physical science during the 

 last fifty years, is embarrassed by the abundance 

 of the objects of choice; and by the difficulty 

 which every one, but a specialist in each depart- 

 ment, must find in drawing a due distinction be- 

 tween discoveries which strike the imagination by 

 their novelty, or by their practical influence, and 

 those unobtrusive but pregnant observations and 

 experiments in which the germs of the great 

 things of the future really lie. Moreover, my 

 limits restrict me to little more than a bare 

 chronicle of the events which I have to notice. 



In physics and chemistry, the old boundaries of 

 which sciences are rapidly becoming effaced, one 

 can hardly '40 wrong in ascribing a primary value 

 to the investigations into the relation between the 

 solid, liquid, and gaseous states of matter on the 

 one hand, and degrees of pressure and of heat on 

 the other. Almost all, even the most refractory, 

 solids have IK-CM vapourised by the intense lu-at 

 of the electric arc ; and the most refra< 



