When he left Paris in 1826 he continued to correspond with Burnouf, and received letters from him subscribed with the cuneiform sign for B (𐎲). Burnouf had in fact long devoted himself to cuneiform studies, as is apparent from his edition of the Yaçna in 1833; but it is not stated when Lassen first directed his attention to the same subject. Both scholars published their essays upon it in 1836. When Burnouf communicated his Memoir to the Academy of Inscriptions, in March 1836, Lassen confesses that he was entirely taken by surprise.[433] His own Memoir on the subject was already in the press, and his preface is dated in May. Both essays were published about the same time, though we cannot say which had the actual priority of appearance. It is perfectly certain that neither scholar was dependent upon the published work of the other, and if they had not been personal friends, the question of the complete independence of their discoveries could never have arisen. As it is, however, we know that in the summer preceding the publication of the Memoirs, Burnouf visited Bonn, and had much conversation with Lassen on the subject of their common pursuits.[434] He told him that he had ‘deciphered the names of all the old Persian provinces,’ which sufficiently indicated the direction of his studies; and it is quite possible that he told him also of his identification of the letters _k_ and _z_ as well as _b_. At all events, his Memoir preceded by a clear month (April) the writing of Lassen’s preface, and he is entitled to claim these two letters. Whatever confidences Burnouf may have imparted, Lassen was evidently more reticent, for although the discoveries of the Bonn professor embraced the re-discovered _b_ of Münter and the _k_ and _z_ of Burnouf, they include also several other correct values of which Burnouf had no knowledge.