In the year 1810 there appeared the first volume of his great work, the _Prodromus Florae Novae Hollandiae_. It is a misfortune that only one volume was ever published, although the work was advanced in MS. It has been said that a criticism of the author's Latinity at the hands of a reviewer was the cause of the stoppage of the publication, but there seems to be no real foundation for the story. Possibly the expense, coupled with the small return, may at any rate partly account for it. Be this as it may, Brown recalled from his bookseller all the unsold copies, and in the copy preserved at the Natural History Museum there is a list of the volumes actually sold written by Brown himself, and from a financial point of view the enterprise clearly proved itself to be an expensive experiment. The volume as published is a remarkable work, containing some 450 pages, including 464 genera, nearly one-third of which are here described for the first time and the number of species amounts to about 2000, some three-quarters of which were new to science. Add to this the fact that the flora as a whole is very unlike that of the northern hemisphere, also that the work was accomplished with such amazing rapidity (largely owing to his particular methods already alluded to), and one cannot withhold admiration at the energy and the learning of its author. It is a wonderful tribute to his wisdom that his descriptions and arrangements should have so stood the test of 100 years, during which time vast strides in our knowledge of the Australian and other floras have been made. But the lapse of time has resulted in scarcely any but trifling modifications of the general results as he left them. The _Prodromus_ is well worth study, for in its pages one constantly meets with hints of observations which have borne fruit in later years. Some of them, indeed, e.g. his observations on Cycads, were expanded by himself into larger treatises in which much light has been thrown on morphological and taxonomic relationships previously but imperfectly understood.