102 POPULAR LECTURES AND ADDRESSES. 



times the maximum density of water, we find 

 6-53 x icr 8 for the maximum density of water 

 according to the universal-gravitation reckoning. 

 To measure mass we must now introduce a unit 

 of length, and if we take this as one centimetre, 

 we find that, as the mass of a cubic centimetre 

 of water at maximum density is very approxi- 

 mately equal to what is called a gramme, the 

 universal-gravitation unit of matter is [i/(6*53 x 

 io~ 8 ) = ] I5*3xio 6 grammes, or 15*3 French tons; 

 hence the unit force on the universal-gravitation 

 system is 15 '6 x io 3 dynes; or 15*6 times the 

 terrestrial weight of a kilogramme. 



15*3 French tons, then (a French ton is 1*4 per 

 cent, less than the British ton), is the universal- 

 gravitation unit of matter. The time may come 

 when the universal-gravitation system will be the 

 system of reckoning; when 15*3 tons will be the 

 unit of matter, and when the decimal subdivision 

 of 15*3 French tons may be our metrical system, 



tions of the torsion-rod. He has expressed the opinion that Bailey's 

 result should, if calculated on thoroughly correct principles, have 

 been in close agreement with his own, which was 5*55. 



