ON THE PROGRESS OF SCIENCE. XVII 



the Deepening of the Mouths; based upon Surveys and Investigations, 

 made under the Acts of Congress directing the Topographical and 

 Hydrographical Survey of the Delta of the Mississippi River, with 

 such Investigations as might lead to the determination of the most 



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practicable plan for securing it from inundation, and the best mode 

 of deepening the channels at the mouths of the river. Prepared by 

 Capt. A. A. Humphreys and Lieut. H. L. Abbot, Corps of Topograph- 

 ical Engineers, U. S. Army ; with maps ; pp. 545. 



This work, which forms one of the professional papers of the U. S- 

 Corps of Topographical Engineers, is one of the most elaborate scien- 

 tific reports ever prepared in this country, and, besides its immediate 

 practical value, contains much information important to the geologist, 

 meteorologist, and to civil engineers generally. It also contains a 

 very full discussion of the theory of hydraulics as applied to rivers. 



The Birds of North America, containing Descriptions of all known 

 Species, chiefly from specimens in the Museum of the Smithsonian In- 

 stitution. By S. F. Baird, with the co-operation of John Cassin and 

 George N. Laurence ; one vol. 4to, with an atlas of one hundred 

 plates, from original drawings, representing one hundred and forty- 

 eight new and unfigured North American birds. A work of this de- 



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scription has been long admitted to be a great desideratum, on account 

 of the numerous additions to our ornithology, and the fact also that 

 there was no work extant which presented a complete and condensed 

 account of all the known birds of the United States to the present 

 time. The magnificent and standard Ornithology of Mr. Audubon, 

 the second edition of which was completed in 1843, embraced very 

 nearly all that was known at that time of the birds of the accessible 

 regions of North America, and contained descriptions and figures of 

 nearly five hundred species. Seventeen years have produced great 

 changes, not only in the boundaries and geographical relations of the 

 United States, but also in the facilities for travel and scientific ex- 

 ploration of the interior and remote regions of our vast territory. 

 Within that period, the thorough exploration of Texas, New Mexico, 

 the countries on the Pacific slope, the Rocky Mountains, and other 

 very extensive and interesting districts of our country, by government 

 expeditions and private enterprise, has correspondingly enlarged our 

 knowledge of North American zoology, and especially of ornithology. 

 In the Eastern and older States, too, quite numerous additions have 

 been made, which, especially in Florida, and elsewhere on the Atlan- 

 tic seaboard, have been of a very interesting character. 



So great has been the increase, from causes here indicated, and the 

 discovery of new birds, that instead of about 495 species of North 

 2* 



