April CalendarFind out what famous event happened on the April
Calendar for history concerning patents, trademarks, or
copyrights. What famous inventor has the same April birthday as
you. April 11953 Arthur Miller's The Crucible a play in 4 acts
was copyrighted. April Fools' Day April 21889 Charles Hall
patented an inexpensive method for the production of aluminum,
which brought the metal into wide commercial use. April 31973
Francis W. Dorion was granted patent #3,724,070 for a "dual
razor blade assembly". April 41978 Francisco Garcia was granted
patent #4,081,909 for "orthodontic pliers". April 51881 Houston
and Thomson were granted a patent for a centrifugal separator -
the creamer. April 61869 Isaac Hodgson received patent #88,711
for the "roller skate". April 71896 Tolbert Lanston was issued a
patent for the monotype printing press. April 81766 The first
fire escape was patented. The contraption was a wicker basket on
a pulley with a chain. 1997 Hooshan Bral received a patent for
an automatically rinsing