36 Prof. F. Slate on a 



with (a), that entails constancy o£ the ratio (a/k), would 

 evidently fix also a common value of the terminal speed,, 

 whatever strength (a) has. Supposing this condition met,, 

 and with (v±—c) given, equation (9) corresponds visibly to 

 equation (5) save in one essential respect : the type of the 

 original equation (7) makes (rn-{) necessarily constant. It is 

 true, the elimination of (mi) would permit assigning any 

 series of epoch-values to that quantity, without influencing 

 the kinematics through the consequent readjustments of 

 force. They might differ arbitrarily or in conformity with 

 a rule laid down. They might follow, for example, the range 

 of (m), as it varies under the rule of equation (4). Yet each 

 such momentary value of (m{) must be rated constant as a 

 parameter, because equation (7) has required that. 



The proposition is defensible that light-speed is also limiting 

 speed for all electrons under any electromagnetic field-forces.. 

 It can borrow some confirmation from forms like equation (6),. 

 which somehow standardize in terms of (c), and it is plausibly 

 consistent with an idea impressed upon relativity regarding 

 (c) as an unexceeded value. That this critical speed should 

 coincide with the wave-speed does not look unreasonable. 

 Only one of these roles for (c), then, would be common to 

 light and gravitation, since the critical speed alone is known 

 in the latter; it separates the ellipse as an orbit from the 

 two other conies. The analogies of these two field-actions 

 might go astray on such an ambiguity. As affording a 

 provisional background for some electronic dynamics, we 

 shall write the above assumption about (c) into our expressions 

 relative to (F). 



Note next how the first of equations (8) in effect suppresses 

 (R), which is passive in the sense of not contributing to the 

 total energy-flux, but merely diverting part of it. It is 

 clearly immaterial whether the diverted energy is reversible- 

 or not. Read the second member as a product' of the true 

 acceleration by an effective inertia*. Since that inertia- 

 factor is here variable, the equation in the form 



p= m2 J-0» l7 »)g .... (io> 



must be incomplete, as judged by equation (1) which becomes- 



* Effective inertia merits wider use perhaps ; it is so variously 

 adaptable to bridge gaps in knowledge or to secure compacter statement. 

 The pure translation that equation (5) supposes may thus replace a 

 screw-motion of a rigid solid having constant mass and moment of 

 inertia. The pitch of the screw would vary. 



