Blaise Pascal was born on this date in Clermont, France in 1623.
"Before Pascal turned 13 he had proven the 32-nd proposition of Euclid and discovered an error in Rene Descartes geometry. At 16, Pascal began preparing to write a study of the entire field of mathematics, but his father required his time to hand total long columns of numbers. Pascal began designing a calculating machine, which he finally perfected when he was thirty, the pascaline, a beautiful handcrafted box about fourteen by five by three inches. The first accurate mechanical calculator was born."1
Pascal was a mathematician of the first order and made major contributions to probability theory. He was also noted for what has come to be known as Pascal's principle which concerns the fact that in a fluid static pressure is exerted on container walls and acts perpendicular to the walls. Pascal's principle indicates that an external pressure applied to the fluid is uniformly transmitted throughout the fluid.2
1. Blaise Pascal; http://www.thocp.net/biographies/pascal_blaise.html
2. 'Physics;' Jonathan S. Wolf; Barron's Educational Series, Inc; Chapter 13, 'Fluids,' Page 183.