122 POPULAR LECTURES AND ADDRESSES. 



never leave the absolute system, if it gave us in 

 all cases convenient numbers ; and it does give 

 us convenient numbers for the measurement of 

 a current, its unit being ten times the " ampere " 

 of the practical system. The unit of resistance 

 in C.G.S., however, is too small, so is the unit 

 of electromotive force. To get convenient numbers, 

 we give names to certain multiples of units, that is 

 all ; and we use these multiples just as long as it 

 is convenient, and not any longer. That is my 

 idea of the practical system to use it for con- 

 venience and as long as it is convenient ; the 

 moment it ceases to be convenient, to throw it 

 overboard and take C.G.S. pure and simple. The 

 Conference at Paris decided upon the practical 

 system, by adopting the units which are now so 

 familiar, the ohm, the volt (taken from the British 

 Association recommendation), and the ampere. 

 The coulomb was also added, and it was most 

 satisfactory to get old Coulomb's name in one 

 of the fathers of electrical science. Then the watt 

 was added by Sir W. Siemens, and it has been 

 generally accepted, and has proved exceedingly 



