Samuel Pierpont Langley was born in Roxbury, Massachussets. He was the son of Samuel and Mary Sumner (Williams) Langley. His ancestors were almost exclusively of English stock, with some slight admixture of Welsh. Some of them emigrated to Massachusetts in the early part of the seventeenth century and experienced the struggles of the times. Among his forebears were Richard, Increase, and Cotton Mather, and Rev. John Cotton, and many men prominent in the history of Massachusetts--members of the Phillips, Sprague, Sumner, Howell, Williams, Pierpont, and Langley families. Among his less known ancestors were mechanics and artisans skilled in various trades, and substantial farmers, men of rugged health and severely upright moral fiber and probity. His father was a wholesale merchant of Boston, but a man of liberal interests. He had a small telescope with which the young Samuel and his brother John Williams watched the building of Bunker Hill Monument. The boys constructed a complete telescope for themselves, grinding and polishing the mirror to an excellent optical figure, and making the entire mounting. With this instrument they made many amateur observations of the heavens. The family were omnivorous readers, and Samuel, as a boy, made frequent use of the excellent public libraries of Boston. As a man he surprised his intimates by his wide knowledge of the English, German, and French classics, his historical research, and his acquaintance with works on astronomical, physical, and mechanical science.