This is the Michell Workshop Viscometer. It was first fully explained with the appropriate theory of lubrication treatment by F.R. Archibald in 1950 in an ASME / ASLE paper. Up until that time, no one, not even its inventor, A.G. M. Michell of Australia, understood the theory behind it. When the paper was published explaining why it worked, the inventor very quickly wrote F.R. Archibald and congratulated him on his landmark paper in which it appeared.
The instrument does not find much use in the U.S., and I suspect has fallen out of favor in Australia and other places. It does have many attractive benefits including simplicity and its ability to measure a wide range of viscosity. One way to spread its capabilities is by using a lighter sphere, instead of steel an aluminum sphere could be used or even one made from glass or plastic.
There are not many of these instruments in existence today. This one survives because I am the son of F.R. Archibald and I believe this instrument was presented to him by either Dudley Fuller, Hersey or Michell; three prominent men in the theory of lubrication.
Access this 2-minute, 25-second video by clicking on the link below.