We now come to the most interesting and confirmatory part of our evidence. We have already referred to the fact that Messrs. Corwin & King give June, 1852, as the date when the wove paper appeared, and 1852 is given in all catalogues and lists as the year of issue for all three stamps on this paper. In their article on British North America, the above gentlemen, in discussing early dates established by entire covers for the varieties of paper that they describe, remark under the caption "_Series IV_." (the _thin wove_ paper): "We took a six-pence from a letter dated June 25th, 1852."[23] This statement can hardly be questioned, after the careful and minute study that they gave to the papers of this issue, and it therefore means just one thing: _the 6d. on wove paper came in the first lot delivered_, for we have seen that the second supply did not arrive until 1855. The fact is therefore established that the first deliveries of stamps in April and May, 1851, included the wove paper, and we therefore have here what amounts to the proper credentials for the appearance and even use of the 12d. on wove paper. [23] Metropolitan Philatelist, I: 149. As the 3d., having been delivered first, was undoubtedly printed first, this value may have been entirely upon the laid paper, particularly as it seems to be not especially rare on this paper and has not been recorded on wove paper used earlier than the receipt of the 1852 supplies. But this of course is negative evidence, and this value may yet be found to have been printed upon the wove paper along with the other two values in 1851. * * * * * We have remarked that there were but three covers known bearing copies of the 12d. stamp. It is with great satisfaction, therefore, that we are able to present reproductions of two of them for the benefit of our readers. The earliest date is on the cover numbered 90 on Plate VI, which is in the Worthington collection. This bears the postmark of "Montreal, L. C. JY 21, 1852" in red. The stamp is a little heavily cancelled by the concentric rings type of obliteration in black. The word CANADA within the curved frame and the word PAID are stamped in red on the cover. This was a requirement of the first postal convention between Canada and the United States, signed on March 25, 1851. Section 9 reads:-- "The Offices designated for the despatch and receipt of Canadian Mails on the side of the United States will stamp 'U. States' upon all letters sent into Canada for delivery; and the Offices designated for the despatch and receipt of United States mails on the side of Canada will stamp 'Canada' upon all letters sent into the United States for delivery."