546 



SCIENCE. 



[N. S. Vol. XIX. No. 483. 



actcrized by broad, flat-topped inter-stream 

 areas, whose summits mark a well-defined 

 plain. The Arctic Slope Eegion includes a 

 small area lying north of the Eocky Moun- 

 tains. 



The model shows not only the relief, but also 

 the distribution of the timber and the mineral 

 deposits, as far as they have been determined. 

 It will be noted that the gold placers have a 

 very wide distribution through Alaska, that 

 copper has been found only in the Pacific 

 Mountain belt, tin at the western end of the 

 Seward Peninsula, while coal has been found 

 in many widely sepai-ated localities. The lode 

 mines which have been developed up to the 

 present day are practically all confined to the 

 Pacific Coastal belt. 



Mr. George B. Shattuck then presented a 

 paper on ' Recent Elevations and Depressions 

 in' the Bahama Islands,' illustrated by stereop- 

 ticon. This paper was based on the results 

 of the expedition sent out by the Geographical 

 Society of Baltimore, and will soon be pub- 

 lished in full. 



A third paper, by Mr. G. K. Gilbert, had 

 for its subject, ' Domes and Dome Structures 

 in the Sierra Nevada,' and is now in print as 

 a bulletin of the Geological Society of Amer- 

 ica. Alfred H. Brooks, 



Secretary. 



BIOLOGICAL SOCIETY OF WASHINGTON. 



The 383d regular meeting of the society was 

 held on Saturday evening, March 5, 1904. 

 Dr. A. K. Fisher delivered an illustrated lec- 

 ture on the ' Birds of Laysan Island,' based on 

 observations made by W. K. Fisher, of Stan- 

 ford University, during the summer of 1903, 

 while connected with the U. S. Fish Com- 

 mission steamer Albatross. Laysan Island, 

 which lies in the Pacific, about 800 miles 

 northwest of Honolulu, is one of the most re- 

 markable bird islands in the world. It is the 

 home of countless thousands of sea birds, such 

 as albatrosses, terns, gannets, .frigates, shear- 

 waters, petrels, etc., and has rarely been vis- 

 ited by naturalists. A most detailed account 

 of the bird population of the island was given. 

 The photographs shown constitute one of the 



most interesting series of bird pictures ever 

 taken.* 



Mr. J. N. Rose exhibited some fifty water- 

 color drawings to illustrate the genera of 

 Crassulacese recently segregated by Dr. N. L. 

 Britton and himself. The drawings are the 

 work of Mr. F. A. Walpole and have been 

 executed with great skill. Mr. Rose pointed 

 out the fact that the number of genera in 

 Crassulaceae as compared with the number of 

 species is very small, and that nearly all the 

 species of the world are to be found in six 

 genera. He states that complaint is often 

 made that the generic limits are very indis- 

 tinct which he thinks can be remedied by in- 

 creasing the number of genera. He finds 

 that Cotyledon, a South African genus, is to 

 be excluded from American groups, and that, 

 in place of it, Echeveria is to be restored. To 

 the latter most of the Mexican species are re- 

 ferred. A new genus, Dudleya, is proposed 

 for certain species from the west coast of 

 North America. Wilfred H. Osgood, 



Secretary. 



THE PHILOSOPHICAL SOCIETY OF WASHINGTON. 



The 581st meeting was held February 27, 

 1904. The Qvening was devoted to aeronauti- 

 cal subjects. 



Dr. A. F. Zahm read a paper on ' Atmos- 

 pheric Friction with Special Referpn.ce to 

 Aeronautics,' giving a partial account of one 

 of the researches on air resistance which he 

 has been conducting the past three years, at 

 the Catholic University of America. His 

 measurements show that the skin friction R, 

 of a thin material plane of length I, and speed 



V moving through still air, is expressed by 

 an equation of the form R = al^v", in which 

 a, m, n are numerical constants for all speeds 

 up to the limit of experiment, which was 

 about 25 miles an hour. For a strip of the 

 plane one foot wide and I feet long moving 



V miles an hour, the above formula gives 

 7^=0.0000336^°''V•»^— ie being in pounds. 

 Applying this equation to practical problems 

 he showed that the element of skin friction is 



* An illustrated account of the birds of Laysan 

 has been published by W. K. Fisher, Bull. U. S. 

 Fish Comm. for 1903, pp. 1-39, pis. 1-10. 



