In addition, Mr Child made an effort to stimulate the collection of such remains of the traditional ballad as still live on the lips of the people in this country and in the British Islands. The harvest was, in his opinion, rather scanty; yet, if all the versions thus recovered from tradition were enumerated, the number would not be found inconsiderable. Enough was done, at all events, to make it clear that little or nothing of value remains to be recovered in this way. To readers familiar with such studies, no comment is necessary, and to those who are unfamiliar with them, no form of statement can convey even a faint impression of the industry, the learning, the acumen, and the literary skill which these processes required. In writing the history of a single ballad, Mr Child was sometimes forced to examine hundreds of books in perhaps a dozen different languages. But his industry was unflagging, his sagacity was scarcely ever at fault, and his linguistic and literary knowledge seemed to have no bounds. He spared no pains to perfect his work in every detail, and his success was commensurate with his efforts. In the Advertisement to the Ninth Part (1894), he was able to report that the three hundred and five numbers of his collection comprised the whole extant mass of this traditional material, with the possible exception of a single ballad.[10] In June, 1896, Mr Child concluded his fiftieth year of service as a teacher in Harvard College. He was at this time hard at work on the Tenth and final Part, which was to contain a glossary, various indexes, a bibliography, and an elaborate introduction on the general subject. For years he had allowed himself scarcely any respite from work, and, in spite of the uncertain condition of his health,--or perhaps in consequence of it,--he continued to work at high pressure throughout the summer. At the end of August he discovered that he was seriously ill. He died at Boston on the 11th day of September. He had finished his great work except for the introduction and the general bibliography. The bibliography was in preparation by another hand and has since been completed. The introduction, however, no other scholar had the hardihood to undertake. A few pages of manuscript,--the last thing written by his pen,--almost illegible, were found among his papers to show that he had actually begun the composition of this essay, and many sheets of excerpts testified to the time he had spent in refreshing his memory as to the opinions of his predecessors, but he had left no collectanea that could be utilized in supplying the Introduction itself. He was accustomed to carry much of his material in his memory till the moment of composition arrived, and this habit accounts for the fact that there are no jottings of opinions and no sketch of precisely what line of argument he intended to take.