Thaddeus Mason Harris, author of the _Journal of a Tour into the Territory Northwest of the Alleghany Mountains_, was one of the coterie of liberal clergymen who occupied the New England pulpits in the early part of the nineteenth century. As a member of this group, Harris’s observations of the Western country are of peculiar interest. He had the training of the typical New Englander--“plain living and high thinking.” Born in Charlestown in 1768, his family were driven from their home at the battle of Bunker Hill, and three years later the father died of exposure contracted during his service in the Revolutionary army. As the eldest of the children, Thaddeus was sent to “board around” among the neighboring farmers, one of whom took sufficient interest in the promising lad to fit him for college. An accidental supply of money at a later period, accepted as a special interposition of Providence, made such an impression upon the young man’s mind that he determined to enter the ministry. He was graduated from Harvard in 1787, in the same class with John Quincy Adams. After a year’s teaching at Worcester, the position was tendered him of private secretary to the newly-chosen President Washington, but an attack of small-pox prevented its acceptance, and the place was filled by Tobias Lear. In 1789 our author was “approbated to preach,” and the following year received his A.M. degree, delivering on the occasion the Phi Beta Kappa address. During the two succeeding years he served as the librarian of his alma mater, and was elected (1792) a resident member of the Massachusetts Historical Society. The year 1793 saw Harris installed as pastor of the first church of Dorchester--a relation which was continued through over forty years of faithful and acceptable service. A careful pastor, he exposed himself during the epidemic of yellow fever in 1802 to such an extent that he contracted the disease, and during his convalescence the Western journey was planned and undertaken as a means of recuperation. In this it was eminently successful, and upon his return to Dorchester Harris plunged anew into literary and philanthropic labors. Within the next few years he aided in founding the American Antiquarian Society, the Massachusetts Humane Society, the American Peace Society, the American Academy of Arts and Sciences, and the Archæological Society at Athens, and was chosen corresponding member of the New York Historical Society. His addresses and sermons on different occasions found their way into print, until nearly sixty were published. Harvard honored itself by conferring upon him the degree of doctor of divinity in 1813, and during his entire later life he acted as overseer in the college corporation. His eldest son, a well-known entomologist, served as Harvard librarian for twenty-five years (1831-56).