The publication of the Percy MS. not only put a large amount of trustworthy material at the disposal of Mr Child; it exposed the full enormity of Bishop Percy's sins against popular tradition. Some shadow of suspicion inevitably fell on all other ballad collections. It was more than ever clear to Mr Child that he could not safely take anything at second hand, and he determined not to print a line of his projected work till he had exhausted every effort to get hold of whatever manuscript material might be in existence. His efforts in this direction continued through many years. A number of manuscripts were in private hands; of some the whereabouts was not known; of others the existence was not suspected. But Mr Child was untiring. He was cordially assisted by various scholars, antiquaries, and private gentlemen, to whose coöperation ample testimony is borne in the Advertisements prefixed to the volumes in the present work. Some manuscripts were secured for the Library of Harvard University--notably Bishop Percy's Papers, the Kinloch MSS, and the Harris MS.,[8]--and of others careful copies were made, which became the property of the same library. In all these operations the indispensable good offices of Mr William Macmath, of Edinburgh, deserve particular mention. For a long series of years his services were always at Mr Child's disposal. His self-sacrifice and generosity appear to have been equalled only by his perseverance and wonderful accuracy. But for him the manuscript basis of The English and Scottish Popular Ballads would have been far less strong than it is.