Heinrich Wilhelm Matthias Olbers was born at Arbergen, a village near Bremen, October 11, 1758. His father was a clergyman who, in addition to considerable mathematical powers, was an enthusiastic lover of astronomy. At the age of thirteen young Olbers became deeply interested in that science. While taking an evening walk in the month of August, he observed the Pleiades, and determined to find out to which constellation they belonged. He therefore bought some books on astronomy, along with a few charts of the sky, and he began to study the science with much enthusiasm. He read every book he could lay his hands on, and a few months sufficed to make him acquainted with all the constellations. In 1777, when in his nineteenth year, Olbers entered the University of Göttingen to study medicine, and at the same time he learned much regarding mathematics and astronomy from the mathematician Kaestner. When twenty-one years of age he observed the stars at Göttingen, and devised a method of calculating the orbits of comets, the idea coming to him while he was attending at the bedside of a fellow-student who had taken ill. “Although not made public until 1797,” writes Miss Clerke, “‘Olbers’ method’ was then universally adopted, and is still regarded as the most expeditious and convenient in cases where absolute rigour is not required. By its introduction, not only many a toilsome and thankless hour was spared, but workers were multiplied and encouraged in the pursuit of labours more useful than attractive.” Towards the end of 1781 he returned to Bremen, settled as a medical doctor, and continued in practice for about forty-one years. But although he had adopted perhaps the most toilsome profession, his love of science prevailed, and night after night he explored the heavens with untiring zeal. He never slept more than four hours, and the upper part of his house in the Sandgasse, in Bremen, was fitted up with astronomical instruments. The largest telescope which he possessed was a refractor 3¾ inches in aperture. He remained in active practice till 1823, when he retired, and was enabled to devote more attention to his beloved science. He died on March 2, 1840, at the advanced age of eighty-one.