William Dwight Whitney (1827-94) was the foremost American philologist and Sanskrit scholar of the nineteenth century. After studying in Germany, then at the forefront of linguistic scholarship, he assumed the chair of Sanskrit at Yale in 1854, with comparative philology added to his professorship in 1869. As well as teaching modern languages, Whitney published over 300 scholarly papers and books, acted as chief editor of the ten-volume Century Dictionary, and co-founded the American Philological Association. This 1867 work is an expanded version of lectures he had given at the Smithsonian Institution and in Boston, rewritten for a wider audience and emphasising the importance of recent German philological scholarship. The first five lectures concentrate mostly on the English language and the study of languages in general, including discussion of regional dialects and American English. The lectures then go on to look at the Indo-European language family as well as methods of linguistic research.