April 13, 1743, is the birthdate of Thomas Jefferson, principal author of the Declaration of Independence and third President of the United States (1801–1809). He was born in Shadwell, Virginia, near the center of the state. He entered the College of William & Mary in Williamsburg at age 16 and became a lawyer in 1767. He spoke five languages fluently and, as a farmer (largely tobacco), he was interested in new mechanical inventions and labor-saving devices. He improved the moldboard part of a plow so that it would lift and turn sod more efficiently. He designed a revolving bookstand that allowed five books to be viewed in one place. In Monticello’s entrance hall, he devised a Great Clock powered by gravity using cannonballs, with wall markings showing the time and the day of the week (its face can be seen from both inside and outside). He also devised a cylindrical wheel cipher for encoding and decoding messages, and he repeatedly improved a letter-copying device called a polygraph constructed of two connected pens.
No comments:
Post a Comment