From my miniscule knowlege of the history of medicine, I suspect that 
inventions like the microtome are more like collaborative efforts, with 
different researchers in different parts of the world building on each others 
efforts.Then at some point, an entrepreneur like Spencer starts manufacturing 
them.

A recent article about Dr Jan Evangelista Purkinje states he, "used the 
forerunner of the modern microtome instead of cutting histologic sections 
freehand with a razor" (1) so he is another contributor.

(1) "The extraordinary career of Dr Purkinje"  Venita Jay M.D., F.R.C.P.C., 
Arch Pathol Lab Med 124: 662-663. May 2000.

Mike Titford
USA  Pathology
Mobile AL