26 PROCEEDINGS OF THE AMERICAN ACADEMY 



iments of my own, that seem to me to go far towards establishing 

 this identity. 



If we can find somewhere in nature a breeze of ether blowing 

 with the necessarily enormous velocity freely through space, and 

 show that it exhibits both qualitatively and quantitatively the 

 same properties as an electric current, the simplest possible suppo- 

 sition that we can make is that they are identical. 



Now, the earth in its daily journey round the sun rushes 

 through the ether that fills all space with enormous velocity, and 

 to the observer on the surface of the earth this is the same thing 

 as if the earth were at rest and the ether flowed by with this same 

 velocity. Just as the observer on the deck of a swift steamship at 

 sea feels the same breeze, whether the ship moves forward with a 

 speed of twenty miles an hour through a calm atmosphere, or the 

 breeze blows with a velocity of twenty miles an hour by the steam- 

 ship when at anchor. 



Now, our problem is to detect and measure this ether breeze, and 

 show that qualitatively and quantitatively it possesses the proper- 

 ties of a current of electricity. This I have done in the following 

 way. 



Before us stands a very sensitive balance, capable of detecting a 

 variation in weight of one part in a million. I have replaced the 

 scale-pans with thin disks of brass, ten centimeters in diameter. 

 Above and below each disk, and supported from the floor of the 

 balance by glass legs, are other similar disks of brass. The two 

 suspended disks are, of course, free to move up and down, but 

 remain at rest so long as the equilibrium of the balance is 

 undisturbed. 



The remaining four disks are rigidly fixed, excepting as each 

 can be raised or lowered by a delicate micrometer screw. For con- 

 venience I will designate the right-hand disks Rt, Rm, and Rb, 

 indicating respectively right-hand top, right-hand middle, and 

 right-hand bottom. Similarly, I will designate the left-hand 

 disks Lt, Lm, and Lb. By means of a suitable battery I may 

 electrify airv of these plates, either positively or negatively. 



Suppose, now, I electrify the beam of the balance, and conse- 

 quently plates Rm and Lm positively. If the distances between 

 plates are in all cases the same, the index will remain at rest. If 

 it deflects, we know the distances are somewhere unequal, and 

 must be adjusted by means of the micrometer, until there is no 

 deflection. 



