In 1842 he visited England and the Continent.

He attended the twelfth meeting of the British Association for the Advancement of Science at Manchester.

He then visited France, Germany, Prussia, Belgium, and Holland.

On returning to New York he took an active interest in the deliberations of the New York Historical Society, made an antiquarian tour to Western Virginia, Ohio, and the Canadas, and published in numbers the first volume of an Indian miscellany under the title of "Oneota, or the Indian in his Wigwam." In 1845 the Legislature of New York authorized him to take a census, and collect the statistics of the Iroquois, or Six Nations, which were published, together with materials illustrating their history and character, in a volume entitled, NOTES ON THE IROQUOIS.
This work was highly approved by the Legislature, and copies eagerly sought by persons taking an interest in the fortunes of this celebrated tribe.

Contrary to expectation, their numbers were found to be considerable, and their advance in agriculture and civilization of a highly encouraging character; and the State has since made liberal appropriations for their education.
In 1846 he brought the subject of the American aborigines to the notice of the members of Congress, expressing the opinion, and enforcing it by facts drawn from many years' experience and residence on the frontiers, that it was misunderstood, that the authentic published materials from which the Indians were to be judged were fragmentary and scanty, and that the public policy respecting them, and the mode of applying their funds, and dealing with them, was in many things false and unjust.