PREFACE. Vv 
would not satisfy the wants of the American public. Written 
in and for Germany, the different subjects were treated of much 
more fully in relation to that country than to the rest of the 
world. In some articles, too, owing to the lapse of time or 
other causes, certain omissions of data occurred, which did not 
allow of their being considered as representing the present state of 
science, or as suiting the wants of the United States. ‘T'his, there- 
fore, has rendered it necessary to make copious additions, altera- 
tions, and abridgments in the respective translations; while, in 
some instances, it has been thought proper to re-write entire 
articles. Several of these original papers have been prepared by the 
Editor, and the remainder kindly furnished by some of his friends. 
Some of these again have relieved him of the burden of translating, 
and have added much to the merit of their work by judicious 
alterations and additions; while others have revised his MSS. and 
enriched them with important suggestions. ‘The authority and value 
of the assistance thus obtained will be sufficiently evident from the 
names of those who have so kindly rendered it. To all he here 
takes the opportunity of returning his warmest acknowledgments. 
The second volume, or the one containing Botany, Zoology, and 
Authropology, has been entirely re-written. The articles in it not 
prepared by the Editor are /nvertebrate Zoology, by Prof. S. 8. 
Hatpeman; Ornithology, by Joun Cassin, Esq.; and Mammalia, 
by Cuarves Grrarp, Esq. 
The friends to whom he is indebted for careful revision of his 
MSS. are, Prof. Wotcotr Gisss (Chemistry); Prof. J. D. Dana 
(Mineralogy); Prof. L. Acassiz (Geognosy and Geology); Dr. Asa 
Gray (Botany); Dr. T. G. Wormiey (Anatomy); and Herman 
Lupewie, Esq. (Geography). 
Those who have assisted him by translating and editing entire 
articles are, Wa. M. Bairp, Esq. (Ethnology of the Present Day) ; 
Major C. H. Larnep, U. 8S. Army (Miktary and Naval Sciences) ; 
F. A. Perersen, Esq. (Architecture); Prof. Cuas. E. BLumENTHAL 
(Mythology and Religious Rites); Prof. Wm. Turner (Fine Arts) ; 
and Samuet Cooper, Esq. ( Technology). 
The Editor is likewise under very great obligations to the 
