If you’re one of history’s greatest electrical inventors, it is only suitable to have stationery that’s equal to your stature.
The central image is of the unfinished Wardenclyffe Tower [1]; other inventions pictured include the oscillation transformer [2], steam-and-gas turbine [3] and a telautomaton [4] (that is, a remote-controlled device; this one is a boat).
Found via (where else?) Letterheady.com [5], an archive of interesting letterheads.