Doctor Who Showed That Cholera Was Waterborne

This page is the CodyCross answer for the clue below from Past and Present Tech, Group 1453, Puzzle 5 (Dot Matrix Printer).

Question is: Doctor Who Showed That Cholera Was Waterborne

and the answer is: JOHNSNOW

Word Meaning:

JOHN — (slang, US) A prostitute's client.

Definitions from Wiktionary.