Nowadays is a well known high school or undergrad lab experiment to determine the specific electron charge by using a Wien-filter setup as described for example here.
Up to now I thought that this experiment dates back to Thomson, but reading his paper about cathode rays I noticed that the experiment described in this paper is not exactly the same (see bottom of page 307 and following).
Thomson seemed to measure the electric and magnetic deflection in two steps independently whereas in the version of the linked Leybold manual above applies both, a magnetic and an electric field at the same time and choose values such that the electric force and the Lorentzforce balance (i.e. such that the beam describes a straight line parallel to the initial velocity vector instead of being deflected).
Did Thomson also do this variant of the experiment (as described in the Leybold manual) and where did he publish it?
If you look at the linked Leybold manual you may notice that the plate distance is pretty large such that the electric field is not uniform. Nevertheless they do their calculations assuming uniformity and introduce a "correction factor" to take the nonuniformity into account. This procedure wouldn't meet standards for a scientific publication. For example you could make the plate distance much smaller compared to the plate dimensions or seriously take the nonuniformity into account.
So, what is the history of this variant of the experiment? Do you have references to historical scientific papers describing exactly this variant of the experiment?