The method of cutting thin sections of rocks and fossils had just been invented by Nicol, and this gave Witham the opportunity for his investigations. His papers are illustrated by the botanist McGillivray, to whom he may have owed some further assistance. Indeed he made little pretension to botanical knowledge, but the opinions which he expresses strike one as remarkably sensible, and he must have been a man of sound judgment, at least in scientific affairs. Witham was the first investigator of that most famous of fossils, _Lepidodendron Harcourtii_; of the Craigleith tree (now _Pitys Withami_), of the Lennel Braes trees (_Pitys antiqua_ and _P. primaeva_), of the Wideopen tree (_Pinites_, now _Cordaites Brandlingi_) and of _Anabathra pulcherrima_. It is curious to notice that the Craigleith tree, a manifest Gymnosperm, was at first (1829) regarded even by the great Brongniart as a Monocotyledon, while others imagined it to be a Lycopod. Witham, however, soon set this right. He always speaks with great respect of Brongniart, then just becoming the recognised leader of fossil botany. The following passage from Witham's memoir on the vegetable fossils found at Lennel Braes, near Coldstream, is of interest. "Now, according to that gentleman's [Brongniart's] opinion, out of six classes ... only two existed at that period [Carboniferous], namely the Vascular Cryptogamic plants, comprehending the Filices, Equisetaceae and Lycopodeae, and the Monocotyledons, containing a small number of plants which appear to resemble the Palms and arborescent Liliaceae. The existence, therefore, of so extensive a deposit of Dicotyledonous plants, at this early period of the earth's vegetation, appears to demand the attention of the naturalist." Brongniart's "Monocotyledons" were no doubt Cordaiteae. Witham, we see, set the great man right as regards the antiquity of Dicotyledons, in which, of course, Gymnosperms were then included. Witham's earlier papers were embodied in his book: _The Internal Structure of Fossil Vegetables found in the Carboniferous and Oolitic deposits of Great Britain, described and illustrated_, 1833. It is dedicated to William Hutton, author, with Lindley, of the _Fossil Flora_ of Great Britain. A passage from the dedication shows that Witham took his work seriously--"To lend my aid in bringing from their obscure repositories the ancient records of a former state of things, with the view of disclosing the early and mysterious operations of the Great Author of all created things, will ever be to me a source of unalloyed pleasure." Witham thus fully realised the important significance of the work on which he was engaged. He must have been an interesting person of a somewhat complex character, and I wish we could know more about him. He died on Nov. 28th, 1844. Like all his family, he was a Roman Catholic[120].