So a buddy of mine loaned me both the items in the title.
The Marshall has not been fired up and has sat in a storage space for a few years. The plug looks to have been replaced as it has the metal band plus screws like someone replaced it.
The variac looks like a chunky old 50's style piece of electronics.
Now here's the catch. The socket on the variac has only the two slots (i.e. no ground) but the Marshalls plug has three prongs.
What is the safest way to connect these two things?
My friend scared me a bit when he said "once every thing is plugged in stand back and touch the string of your guitar with just one finger you might get a shock."