46 MATTER AND FORCE, IN PHYSICAL PHENOMENA. 



Must we not apply the same term to those repulsions 

 which occur in the material world most obviously in 

 the atomic actions and changes of matter, and in elec- 

 tric and magnetic phenomena ; but even, as we have 

 some reason to suppose, in cosmical changes beyond 

 the limits of our own globe ? Boscovich admitted this 

 as a part of his theory of forces, and some later phy- 

 sicists have followed him in the same view. Other 

 forms of power, again, we designate by this one short 

 word, so familiar in use, so difficult of scientific defini- 

 tion. The centrifugal force, though defined only as 

 an antagonism, must still be admitted into reality as 

 such. The force of cohesion, denoting perhaps only 

 one mode of action of a larger power, must yet be 

 recognised as an exponent of phenomena which cannot 

 otherwise be understood. 



The difficulties thus pressing upon every abstract 

 conception of force in the universe are not abated 

 when we bring the question to particular physical 

 questions such, for instance, as the velocity involved 

 in the action of forces. We know from astronomical 

 facts, with the recent concurrence of actual experi- 

 ment, the velocity of those undulations which bring 

 light and heat to the earth. We know that the velo- 

 city of electrical transmission, and therefore of mag- 

 netic force, has a close parity with this wonderful rate 

 of motion of light. But though transcending all 

 human conception, we are compelled, if adopting the 

 conclusions of Laplace, to suppose an incomparably 

 greater velocity in the force of gravitation. Time, in 

 truth, is virtually ajmulled in estimates of this nature ; 



