Webster, who was an ardent sportsman and well acquainted with the water fowl of the coast, had volunteered to procure for Audubon specimens of the Labrador Duck, which was even then extremely rare and has since become extinct, but was unable to fulfill his promise. Audubon had already found that many American birds, like the common crow, which had been regarded as identical with those of the Old World, were in reality distinct, and was now anxious, as he wrote to Thomas Brewer, "to compare the anatomy of all our birds with those of the same families in Europe." His letters to young Brewer at this time show how eager he was to secure the promised specimens. On October 23 he wrote from Philadelphia: "I hope you will not forget to call on our enlightened statesman D. Webster, and remind him of his kind promise to assist you in the procuring of specimens for me. This winter and next spring are my only chances, and I beg you to do all you can for me." He wrote again from Charleston, January 1, 1837: "I am sorry that the Hon. D. Webster has not attended to his promises, and will write to him; yet I would beg you, being on the spot, _to trouble him a good deal_."[139] After returning to New York, Audubon had a visitor for whom he expressed the greatest admiration, Washington Irving, who had aided him in 1833; he now received from his hands letters to Martin Van Buren, the President-elect, and Benjamin F. Butler, who then occupied the post of Attorney-General. Irving called attention in his letter to the national character of Audubon's work, and warmly commended it to the patronage of the country at large. On October 8 Audubon wrote MacGillivray from New York that he had obtained twelve new subscribers, two at Salem, four at Boston, and six in New York, but a little later, through the aid of Nicholas Berthoud, in one week's time eighteen new names were added to his subscription list in New York City alone. Meanwhile Nuttall's and Townsend's birds had not been forgotten, and on October 15 he started with his son for Philadelphia, where he was again welcomed by Dr. Richard Harlan. No sooner, however, were efforts renewed to gain permission to study the desired objects than new obstacles were encountered. To quote the naturalist:[140] Having obtained access to the collection sent by Dr. Townsend, I turned over and over the new and rare species, but he was absent at Fort Vancouver, on the shores of the Columbia River; Thomas Nuttall had not yet come from Boston, and loud murmurs were uttered by the _soi-disant_ friends of science, who objected to my seeing, much less portraying and describing, those valuable relics of birds, many of which had not yet been introduced into our Fauna. At length, "it was agreed," to continue his account of the transaction,