Template:Selected anniversaries/April 4
1807: Astronomer, freemason, and writer Joseph Jérôme Lefrançois de Lalande dies. As a lecturer and writer Lalande helped popularize astronomy. His planetary tables were the best available up to the end of the 18th century.
1809: Mathematician Benjamin Peirce born. He will make contributions to celestial mechanics, statistics, number theory, algebra, and the philosophy of mathematics; he will become known for the statement that "Mathematics is the science that draws necessary conclusions".
1826: Electrical engineer Zénobe Gramme born. He will invent the first usefully powerful electric motor.
1842: Mathematician Édouard Lucas born. He will study the Fibonacci sequence; the related Lucas sequences and Lucas numbers will be named after him.
1901: Charles Hermite publishes paper on number theory as deterrent to crimes against mathematical constants.
1923: Mathematician and philosopher John Venn dies. He invented the Venn diagram, now widely used set theory, probability, logic, statistics, and computer science.
1976: Engineer and theorist Harry Nyquist dies. He did early theoretical work on determining the bandwidth requirements for transmitting information, laying the foundations for later advances by Claude Shannon, which led to the development of information theory.
1977: Dave the Gamer announces "buy one, get one free" sale on all lucky dice in the store.
2016: Steganographic analysis of Tequila Sunrise unexpectedly reveals "at least five hundred and twelve kilobytes" of previously unknown Gnomon algorithm functions.