June 4, 1897. ] 



SCIENCE. 



889 



C.G.S. units, they have found that the percent- 

 age hroadening is directly proportional to the 

 field strength; the absolute amount for sodium 

 in a unit field being 11.46 -10^^° Angstrom units. 



A. A. Michelson describes some recent ex- 

 periments, having as their object the discussion 

 of the question as to whether there is a relative 

 motion of the earth and the ether. Light from 

 a certain source was separated into two pencils 

 by a plane-parallel glass plate, and carried by 

 two equal paths back to the observing tele- 

 scope, where the interference fringes resulting 

 could be observed. The apparatus was set up 

 in a vertical east and west plane, the path be- 

 ing 200 feet long and 50 feet high. In order to 

 eliminate disturbances due to temperature, the 

 path of the light was inclosed in an iron pipe 

 exhausted to within xlir of an atmosphere. 

 It was then found possible to measure the posi- 

 tion of the central bright fringe to within some- 

 thing like ^V of a fringe-width. The results 

 of the measurements go to show that if there is 

 any displacement of the fringes it is less than 

 2V of a fringe. Hence it follows that the 

 earth's influences upon the ether extends to dis- 

 tances comparable to the earth's diameter. 

 The author concludes by saying that with 

 these results before us we are driven to one of 

 the three following extraordinary conclusions: 



"1. The earth passes through the ether (or 

 rather allows the ether to pass through its en- 

 tire mass) without appreciable influence. 2. 

 The length of all bodies is altered (equally?) by 

 their motion through the ether. 3. The earth 

 in its motion drags with it the ether even at 

 distances of many thousand kilometers from its 

 surface." 



SOCIETIES AND ACADE3IIES. 

 GEOLOGICAL SOCIETY OF WASHINGTON, MEET- 

 ING OF MAY 12, 1897. 



Under the title ' Physiography of the West 

 Coast -of Peru,' Mr. S. F. Emmons described 

 some of the prominent physiographic features 

 noted by him during a recent and rather hur- 

 ried journey along the west coast of Peru as far 

 as 16° south latitude, and on a trip on the 

 Oroya railroad from Lima up to the western 

 crest of the Andes and back. 



First, he noticed the remarkable diflerence 

 in rainfall and consequent change in vegetation 

 experienced in the few hours' sail from the 

 mouth of the Guayaquil River, in Ecuador, to 

 the most northern part of Peru. From a region 

 of copious rains and tropical luxuriance of 

 vegetation and often dense forests one passes, 

 over night, to a region where it rains once 

 in seven years, and farther, to where it is 

 absolutely rainless. As far as seen, there is no 

 tree growth on the west slope of the Andes in 

 Peru. In the larger valleys, on the other 

 hand, where irrigation is possible, sugar, cot- 

 ton, and all varieties of cereals, vegetables and 

 fruits flourish under cultivation. The most 

 evident cause of this condition of things lies in 

 the fact that the wind along the coast blows 

 almost continuously from the south, coming 

 from a colder to a warmer atmosphere, or one 

 whose capacity for carrying moisture is con- 

 stantly increasing. Hence there is no conden- 

 sation until the wind currents strike the high 

 mountain slopes. In Ecuador the influence of 

 the highly-charged equatorial currents is felt, 

 and near the mouth of the Guayaquil River the 

 continental watershed pushes westward to 

 within 50 miles of the coast, thus presenting a 

 condensing barrier on the land to the north- 

 ward-moving currents. 



A second striking feature is the enormous ex- 

 tent to which the coast bluffs and the northern 

 slopes of the mountains that approach the sea 

 are covered by white drifting beach sands borne 

 along by the same prevailing south wind. At 

 one point these sands, beautifully ripple- 

 marked, completely mantled the southeast 

 side of a deeply cut mountain valley to an ele- 

 vation of four to five thausand feet above the 

 sea level, and sand fields were observed inland, 

 along north and south depressions in the ele- 

 vated plateaux or pampas, 40 to 50 miles from 

 the coast. 



Striking evidences of recent elevation and 

 subsidence of the coast regions are most fre- 

 quent, and where the coast line is formed, as it 

 frequently is, of soft and readily disintegrable 

 Tertiary beds it is seen to be rapidly wearing 

 away under the influence of the long and 

 powerful waves of the Pacific Ocean. Near 

 Pacasmayo a river valley is seen to have been 



