An Improved Door Check

00

This article was originally published with the title “An Improved Door Check” in Scientific American Magazine Vol. 62 No. 13 (March 1890), p. 197
doi:10.1038/scientificamerican03291890-197d

View This Issue

Expand Your World with Science

Learn and share the most exciting discoveries, innovations and ideas shaping our world today.

Subscribe Sign up for our newsletters See the latest stories Read the latest issue Give a Gift Subscription

Return & Refund Policy
About
Press Room

FAQs
Contact Us
International Editions

Advertise
Accessibility Statement
Terms of Use

Privacy Policy
California Consumer Privacy Statement
Use of cookies/Do not sell my data

Scientific American is part of Springer Nature, which owns or has commercial relations with thousands of scientific publications (many of them can be found at www.springernature.com/us). Scientific American maintains a strict policy of editorial independence in reporting developments in science to our readers.