328 



SCIENCE 



[N. S. Vol. L. No. 1292 



Moulton that he has gone oyer the old f onnulse 

 used and has found that the computer intro- 

 duced the factor cos^ erroneously into the 

 W.-S. computation. 



The ]Sr.-S. ratio should therefore have been 



.523 



■ „„ ,- = .710, which oddly enough is exactly 



.YoDo 



equal to the E.-W. ratio. 



The new observations point to a value of 



about .69 for both E.-W. and N.-S. ratios. 



A. A. MiCHELSON, 



Heney G. Gale 

 . The TIniversitt op Chicago, 

 September 10, 1919 



AN UNUSUAL MIRAGE 



Most people are probably familiar with the 

 type of mirage often seen over paved streets on 

 still hot days. In its simplest and most com- 

 mon form one appears to see merely a wetted 

 portion of the pavement some distance ahead. 

 In more striking cases this assumes the ap- 

 pearance of a pool of water in which buildings, 

 trees and vehicles are seen reflected. As is 

 well known this is due to the presence just 

 above the pavement of a layer of air which 

 being warmer than that above it is lighter 

 and hence has a lower index of refraction than 

 the air a little distance from the surface of 

 the earth. These mirages are oftenest seen in 

 mid-afternoon, and when motoring through 

 the country such a pool often appears to con- 

 tinually recede and thus remains in sight for 

 a long time. Recently while traveling from 

 San Francisco to Portland with Professor 

 W. C. Morgan we encoimtered such a mirage 

 under rather unusual conditions. 



The section of the Pacific Highway which 

 traverses the Sacramento valley being paved 

 with cement and under a hot sim is an ideal 

 place for such mirages which had been visible 

 much of the afternoon. Just after dusk 

 (about nine o'clock) a ear with powerful lights 

 came over a slight rise a mile or so ahead. A 

 moment later the lights of a second car ap- 

 peared some distance in front of the first as 

 though the driver had just turned them on. 

 These lights were about half as brilliant as 

 those of the first car and the impression was 



that two cars were approaching — a small one 

 followed by a larger one. The large car was 

 seen to gradually overtake the small one 

 until finally the two sets of lights coalesced 

 and a minute later we met and passed — a 

 single car. "I thought there were two of 

 them," said Dr. Morgan. So did I. "We had 

 seen a mirage at night. 



A. A. Knowlton 

 Eeed College 



QUOTATIONS 



THE ROCKEFELLER FOUNDATION 



A review of the work of the Eochefeller 

 Foundation in various countries during 1918 

 by the president, Mr. George E. Vincent, 

 shows that its activities extended literally 

 from China to Peru. The foundation has 

 shown practical interest in advanced medical 

 education in hygiene in two ways. In the 

 first place it has by gifts for building, equip- 

 ment, and maintenance, rendered possible the 

 opening last October of the school of hygiene 

 and public health at Johns Hopkins Univer- 

 sity in Baltimore. In the second place it has, 

 since 1915, followed the policy of granting a 

 number of international fellowships and schol- 

 arships to students from foreign countries 

 and American missionaries at home on leave. 

 In 1918 there were 68 fellowships and schol- 

 arships distributed as follows: Brazilian phys- 

 icians 3, Chinese graduate physicians 11, 

 Chinese undergraduate medical students (for- 

 merly students of the Harvard Medical School 

 of China) 10, Chinese pharmacists 3, Chinese 

 nurses 6, medical missionaries on furlough 26, 

 candidates under consideration for the new 

 schools at Peking and Shanghai 9. The In- 

 ternational Health Board has adopted a sys- 

 tem of " study leave," by which members of 

 its staff of medical officers, now nearly 60 in 

 mmaber, may, under favorable conditions of 

 salary, pursue at the expense of the board 

 special courses in public health at leading 

 American or foreign institutions. In this 

 way the equivalent of additional graduate 

 fellowsliips has been created. Provision was 

 also made for the bringing to the United 

 States French medical men for special train- 



