300 On the Physical Units of Nature. 



Lx=C Yv me ^ res ? (10) 



Tl=C 3XxITT seconds? ' ' ' ^"^ 



M 1= =C XV grammes (12) 



In obtaining these equations we have only used the nume- 

 rical values of V x and Gi, which are known to a satisfactory 

 degree of approximation ; and if we go no further, there will 

 remain but one arbitrary member in the entire of the resulting 

 series of systematic physical units. 



12. If we also introduce the numerical value found above for 

 C, which depends on E x and is less accurately known, we ob- 

 tain the following actual values for these units of Nature : — 



L x = of a metre; . . . (13) 



T x = q - xrT T7 . of a second ; . . . (14) 



M x = VTT of a gramme. . . . (15) 



Or, in other words — 



The natural unit of length approaches in value to the thirty- 

 seventh metre (i. e. the metre divided by 10 37 ). 



The natural unit of time approaches in value to one third of 

 the forty-fifth second (i. e. one third of the second of time 

 divided by 10 45 ) ; and 



The natural unit of mass approaches to the seventh gramme 

 (i. e. the gramme divided by 10 7 ). 



13. This appears the best attempt we can yet make to de- 

 termine these remarkable units. In the series to which they 

 belong all the electrostatic units will be identical with the 

 corresponding electromagnetic units, all the forces of Nature 

 that are known to obey the law of the inverse square, whether 

 they arise from gravitation, electricity, or magnetism, will be 

 expressed without coefficients, and the chemical bond, which 

 seems to be the unit of concrete Nature, is brought into its 

 proper relation to physics. 



Postscript. — Many persons find it difficult to conceive of G 1 

 as a unit. G 1 may be avoided and M x be substituted for it, 

 if M x be defined as a mass such that it attracts an equal mass 

 at a distance with the same force with which two units of 

 electricity, as defined above in section 5 (i. e. each equal to 

 Ex), would, if placed at the same distance asunder, act on each 

 other. The three fundamental units of the Natural System 

 will then be V l5 E 1? and M 1? from which all others are to be 

 derived. This M : is the same as the M x of sections 11 and 12. 



