For 10 points, name this British scientist who names an absolute temperature scale and the SI unit of temperature.
Along with a German, this man names a phenomenon caused by a velocity discontinuity across a vortex sheet. This man's brother James predicted that pressure would lower the melting point of ice. This man obtained his first patent for the siphon recorder. He also patented the mirror galvanometer around the same time that he was involved in laying the transatlantic telegraph cable. The triple point of water is used to define a unit named for this man. For 10 points, name this British scientist who names an absolute temperature scale and the SI unit of temperature.
Along with a German, this man names a phenomenon caused by a velocity discontinuity across a vortex sheet.
Lord {Kelvin} [or William {Thomson}; or 1st Baron {Kelvin}]