Someone did a TIL on reddit and I popped in to answer questions there, too. http://www.reddit.com/r/todayilearned/comments/obyxj/til_that_nicola_tesla_invented_

Someone did a TIL on reddit and I popped in to answer questions there, too. http://www.reddit.com/r/todayilearned/comments/obyxj/til_that_nicola_tesla_invented_a_valve_that_lets/ http://www.reddit.com/r/todayilearned/comments/obyxj/til_tha...