published on: 2013-12-04 14:17:28
cid25.tumblr.com/post/68976802238/
engineeringhistory: William Coolidge holding an X-ray tube,
cid25.tumblr.com/post/68976912126/
cid25.tumblr.com/post/68976916997/
cid25.tumblr.com/post/68977190222/
highgatedreams: By Sakessu on Flickr