Science on the 20th of May 1856 in history

What happened on this day in history?

OnThisDay.net is your complete guide to find out what happened on this day in History. The front page on this site shows you a series of important happenings and you can browse them buy categories such as births, deaths, events, science, history, music, news and holidays. We have also added an anniversary tab displaying happenings deserving extra attention today. If you are missing an important happening we made it easy for you to add it to the list. Just click add event, fill out the form and your suggestion will be revised by one of our staff. Please feel free to vote on your favourite events. This will help us in our effort to display the most popular events first and make the site more interesting for the next visitor, as events with many votes eventually will be shown first.