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would be dislodged from our universe j casual relations 

 would disappear, and with them that science which is 

 now binding the parts of nature to an organic whole. 



I should like to illustrate by a few simple instances 

 the use that scientific men have already made of this 

 power of imagination, and to indicate afterwards some 

 of the further uses that they are likely to make of it. 

 Let us begin with the rudimentary experiences. Observe 

 the falling of heavy rain drops into a tranquil pond. 

 Each drop as it strikes the water becomes a center of 

 disturbance, from which a series of ring ripples expands 

 outwards. Gravity and inertia are the agents by which 

 this wave motion is produced, and a rough experiment 

 will suffice to show that the rate of propagation does 

 not amount to a foot a second. 



A series of slight mechanical shocks is experienced 

 by a body plunged in the water as the wavelets reach it 

 in succession. But a finer motion is at the same time 

 set up and propagated. If the head and ears be im- 

 mersed in the water, as in an experiment of Franklin's, 

 the shock of the drop is communicated to the auditory 

 nerve the tick of the drop is heard. Now this 

 sonorous impulse is propagated, not at the rate of a 

 foot a second, but at the rate of 4,700 feet a 

 second. In this case it is not the gravity but the 

 elasticity of the water that is the urging force. Every 

 liquid particle pushed against its neighbor delivers up 

 its motion with extreme rapidity, and the pulse is propa- 

 gated as a thrill. The incompressibility of water, as 

 illustrated by the famous Florentine experiment, is a 

 measure of its elasticity, and to the possession of this 

 property in so high a degree the rapid transmission of 

 a sound-pulse through water is to be ascribed. 



