English: Preston in his work on the Zeeman Effect made use of 3 magnets and this one in the picture is the one with which he performed his most important experiments. He borrowed it from Monsignor Molloy (his predecessor) and with it he was able to obtain magnetic field strengths of 25,000 c.g.s. units (about 2.5 Tesla).
The cylindrical holes in the pole faces allowed the spectral discharge to be viewed parallel to the magnetic field as well as transversely.
to share – to copy, distribute and transmit the work
to remix – to adapt the work
Under the following conditions:
attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.