Bessel, Friedrich Wilhelm, born at Minden in 1784, and brought up as a merchant, was attracted during a voyage to the study of navigation and astronomy. Some observations which he published brought him into notice, and in 1810 he was made director of the new observatory at Konigsberg. In 1818 he produced his Fundamentum Astronomiae, a work that placed him in the first rank of astronomists. He was especially skilful in the use of delicate instruments, as was shown by his determination of the parallax of 61 Cygni. He died in 1846.