Question

It's written in my book:
Mass of these particles was found equal to that of a proton or simple multiple of it.
Explanation:
It means that each positive ion was found equal to that of a proton. It is in the discovery of canal rays.
Question:
I want to understand that what is meant by simple multiple of it and how did they know the mass of proton as it was not discovered before.

Answer 1

Mass of these particles was found equal to that of a proton or simple multiple of it.

Explanation:

It means that each positive ion was found equal to that of a proton. It is in the discovery of canal rays.

Question:

I want to understand that what is meant by simple multiple of it and how did they know the mass of proton as it was not discovered before.