Editing 1921 in science (section)

==Deaths==
* January 20 – [[Mary Watson Whitney]], American [[astronomer]] (born [[1847 in science|1847]])<ref>{{cite book|first=Robert|last=McHenry|title=Liberty's Women|location=Springfield|publisher=G. & C. Merriam|year=1980|page=442|isbn=978-0-87779-064-8}}</ref>
* January 23 – [[Heinrich Wilhelm Gottfried von Waldeyer-Hartz]] (born [[1836 in science|1836]]), German [[neuroanatomist]].
* March 11 – [[Sherburne Wesley Burnham]] (born [[1838 in science|1838]]), American astronomer.
* March 29 – [[John Burroughs]] (born [[1837 in science|1837]]), American [[Natural history|naturalist]].
* June 7 – [[Hans Christian Cornelius Mortensen]] (born [[1856 in science|1856]]), [[Danes|Danish]] [[ornithologist]].
* August 29 – [[Joel Asaph Allen]] (born [[1838 in science|1838]]), American [[zoologist]].
* October 23 – [[John Boyd Dunlop]] (born [[1840 in science|1840]]), British [[inventor]].
* December 12 – [[Henrietta Swan Leavitt]] (born [[1868 in science|1868]]), American astronomer.