ADVERTISEMENT. 
Upon the organization of the Smithsonian Institution, the Secretary 
Professor Joseph Henry, proposed the publication of a series of " Contributions 
to Knowledge," to consist of " memoirs on different branches of science em- 
bracing the records of extended original investigations and researches resulting 
in what are believed to be new truths and constituting positive additions to the 
sum of human knowledge." 
As a part of the original programme of operations there was also a series of 
" Reports on the progress of knowledge," to be of a more popular nature and 
intended for wider distribution than the " Contributions." 
The second of the latter series undertaken by the Institution was announced 
in the Secretary's report for 1848 and fully described in that for 1849, as follows : 
" The most important report now" in progress is that on the forest trees of 
North America, by Dr. Asa Gray, Professor of Botany in Harvard University. 
It is intended in this w^ork to give figures from the original drawings of the flowers, 
leaves, fruit, etc., of each principal species in the United States proper, for the 
most part of the size of nature, and so executed as to furnish colored or uncolored 
copies — the first being intended to give an adequate idea of the species and the 
second for greater cheapness and more general diffusion. 
'■ This work will be completed in three parts, in octavo, with an atlas of 
quarto plates, the first part to be published next spring. A portion of this will 
be occupied with an introductory dissertation giving the present state of our 
knowledge, divested as much as possible of all unnecessary technical terms of 
the anatomy, morphology, and physiology of the tree, tracing its growth from 
the embryo to its full development and reproduction in the formation of fruit and 
seed. This will be illustrated by drawings from original dissections under the 
microscope and sketches made in every instance from nature. As the work will 
be adapted to general comprehension, it will be of interest to the popular as well 
as the scientific reader." * 
Professor Henry states in his report for 1850 that "the preparation of the 
report on the forest trees of North America, though delayed in consequence of 
the absence of the author, Dr. Grray of Harvard University, on a visit to Europe, 
is still in progress. The illustrations are in the hands of the artists, and the first 
part will probably be published during the present year. The cost of this report, 
* Fourth Annual Keport of Professor Henry, for 1849. 
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