DEVELOPMENTS IN PHYSICAL SCIENCE 447 
RECENT DEVELOPMENTS IN PHYSICAL SCIENCE 
By Prorgssor ARTHUR L. FOLEY 
INDIANA UNIVERSITY 
i ik HERE has been a revolution in the physical science of to-day 
compared with the physical science of twenty-five years ago. 
In the first place there has been a revolution in the methods of teaching 
science. The physics laboratory of the University of Berlin was 
founded in 1863, the Cavendish Laboratory, of Cambridge, in 1874. 
In 1871 Professor Trowbridge, of Harvard, was obliged to borrow cer- 
tain electrical measuring instruments, as the university had none of its 
own. It is not surprising, then, that twenty-five years ago there were 
in the United States very few physics laboratories worthy of the name. 
Physics teaching in college and high school was chiefly from the text- 
book. To-day a college which would offer work in physics without a 
laboratory would be considered a joke; and in order to be commissioned 
to enter its students into the freshman class of a college, a high school 
must have a certain minimum of laboratory equipment and the physics 
teacher must devote a part of his time to laboratory instruction. 
In the second place there has been a complete change in the attitude 
of men of affairs toward the physics professor and his students. No 
longer do they consider us theoretical, and therefore impractical. No 
longer do they look with distrust or contempt on laboratory methods 
and data. No longer do they hold that apprenticeship and experience 
are sufficient for their needs. To-day the large industrial concerns are 
establishing laboratories of their own and employing in them the best 
trained men they can command. 
In the third place there has been a revolution in some of our physical 
theories. By the term revolution I do not mean a destructive upheaval in 
which the work of the past has been repudiated and destroyed and a 
new order of things established. I mean that some of our ideas have 
undergone such a complete and rapid change that what some might 
term an evolution is really a revolution. Indeed, we have had two 
revolutionary periods within the past twenty-five years. 
The first came in 1887 with the epoch-making researches of Hein- 
rich Hertz. Faraday had given us his theory of lines of force and the 
mathematicians had attacked it. Young and Fresnel had given us the 
undulatory theory of light and Laplace and Poisson had “ befuddled us 
with their objections.” Ampére had given a theory of magnetism, but 
Poisson and Weber had given two others. To explain an electric 
charge we could resort to the one-fluid theory, the two-fluid theory, the 
potential theory, the energy theory, the ether strain theory. Maxwell 
