Joseph John Thomson

“ If A represents a particle with a threefold charge there will be another stronger parabola B for which e/m has three times the value corresponding to the parabola A, and B will have a prolongation towards the vertical axis extending to one third of the normal distance. ”

“ After the metal or other solid under examination has been placed on the platform, the taps between A and B are turned and A is exhausted by a Gaede pump until the vacuum is low enough to give cathode rays. The electric discharge is then sent through A and the solid on the platform bombarded. The result of the bombardment is that in a few seconds so much gas, mainly CO2 and hydrogen, is driven out of the solid that the pressure gets too high for the cathode rays to be formed, and unless some precautions to lower the pressure were taken the bombardment would stop. ”

“ Again, If a substance is only present to the extent of a few per cent It very often happens that its spectrum is completely swamped by that of the more abundant substance: thus, for example, in a mixture of helium and hydrogen we cannot observe the helium lines unless the helium is a considerable percentage of the mixture. ”

“ There is always a circular patch of some size on the plate at the place, where the undeflected particles hit the plate: the zero is at the centre of the spot. By putting the needle first at the centre of the spot, then moving the carrier through a certain distance perpendicular to BB by the screw S, and sliding the carrier parallel to BB until the needle comes on the parabolas In turn, the values of y for the different parabolas corresponding to a constant value of x can be measured. ”