This question has been closed:
*https://physics.stackexchange.com/questions/688998/how-was-mass-increase-measuredMeasurement*
because:

> I’m voting to close this question because *it concerns the history of physics –* Bob D

and then:

> Closed. *This question is off-topic*. It is not currently accepting answers.

I have been around for a few years and have never heard anything so weird.

There are loads of questions bordering history, but mine does not:
- *https://physics.stackexchange.com/questions/68471/who-and-why-started-the-electrons-are-negative-protons-are-positive-convent/68475#68475*

And many more concerning past experiments:
- *https://physics.stackexchange.com/questions/95801/how-to-measure-the-mass-of-the-electron/95816#95816*.
 I have chosen two examples answered by an illustrious member, and I hope there was no discrimination.

As I clearly explained, the question was absolutely legitimate, since in 1894 the mass spectrometer was not yet available and [Thomson][1] had not even discovered the electron. Is that really off-topic?

  [1]: https://en.wikipedia.org/wiki/J._J._Thomson