Walter Kaufmann

“ The electron is to be considered as a rigid sphere, uniformly charged over its surface or its volume.
The good agreement of my previous measurements with the consequences drawn from this assumption by application of the Maxwell-Lorentz equations, at first seem to justify the conclusion that the question after the constitution of the electron is definitely solved.
A recent investigation by H. A. Lorentz [3] , however, led to the surprising result that an agreement with my previous experiments can be achieved using totally different assumptions on the electron. ”

“ Thus a auxiliary table is calculated, which gives the -values corresponding to a most tight row of -values, then (when the constants and are known) the corresponding by equation (7.) can be compared to every . It is easily achieved to find approximate values for both "curve constants" and , and then to calculate the improvements still to be made, by the method of least squares.
The curve constants determined in this way, can be compared with those values partly given from the dimensions of the apparatus alone, and partly from the connection with the value found with respect to cathode rays. ”

“ Furthermore, let and the magnetic and electric deflections; eventually let and be the "electric" and "magnetic field integral" reduced to proportionality with the deflectabilities; i.e. two quantities equal to the mean field strength with a factor each dependent on one of the dimensions of the apparatus. At last let , where is the speed of light. It is
where is a function of velocity, whose form is different depending on the basic assumption concerning the constitution of the electron. ”