Dictionary.com
Thesaurus.com

stadiometer

British  
/ ˌsteɪdɪˈɒmɪtə /

noun

  1. an instrument that measures the length of curves, dashes, etc, by running a toothed wheel along them

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of stadiometer

C19: from stadio- , from stadium + -meter