590 



SCIENCE 



[N. S. Vol. XLV. No. 1171 



formed their former estuaries into alluvial 

 plains above vchicli rise scattered rocky isl- 

 ands. This is particularly true of the north- 

 ern tributaries of the lower Amazon, except the 

 Trombetas, which has relatively clear water, 

 and has not yet filled its estuary. 



The author suggests that the physiographic 

 features described above may be interpreted as 

 the result of a moderate drowning of the re- 

 gion followed by the fiUing up of the estuary 

 of the Amazon by the heavy silt burden borne 

 by that river: 



Gradually the alluvial land at the head of the 

 bay extended eastward, filling up the estuary with 

 islands. As this eastward movement went on, the 

 branch estuaries were blocked up at their mouths 

 by islands which formed in front of them. Where 

 the branch received a muddy tributary it also filled 

 up; but the clear water tributaries like the Tapa- 

 jos, Xingli, and Trombetas, brought down no sedi- 

 ment, and their estuaries, closed at the mouths, as- 

 sumed the form of lakes. 



That the phenomena described are the re- 

 sult of changes in level and not merely of the 

 ponding of the tributaries by sediment from 

 the Amazon, is indicated, as the author points 

 out, by the fact that the Tocantins Eiver, 

 which enters the sea directly, has a similar 

 estuary. 



The physiographic phenomena here described 

 seem to point to a relatively recent period of 

 lowered sea level (or land uplift) followed by 

 a rise to the present position (or a sinking of 

 the land). The phenomena may have been as- 

 sociated with the changes in sea level postu- 

 lated by Daly, or they may be due to local 

 crustal movements. Physiographic studies of 

 a large number of tropical rivers would go far 

 toward solving the problem. 



John L. Eioh 



University of Illinois 



QUOTATIONS 



A PIONEER IN PHYSICS 



PoETY-SEVEN years of collegiate teaching con- 

 stitute in themselves a sufficient title to honor, 

 even though their nimiber be only a record of 

 faithful and continuous service. When the 

 passing of these years has told also a story of 



important pioneer work, of purposeful achieve- 

 ment and steady progress, it becomes a record 

 to conjure with. Of such is the repute that 

 Professor Charles R. Cross has established in 

 the long period of his association with the 

 Massachusetts Institute of Technology, and of 

 such the honor which the institute and all men 

 are glad to accord him as he now lays hold 

 upon the satisfactions of a well-earned retire- 

 ment. Being graduated from Massachusetts 

 Institute of Technology in 1870, with the third 

 class that went out from its halls. Professor 

 Cross forthwith returned after the summer va- 

 cation to take up an instructorship in the de- 

 partment of physics. Upon completing a 

 single year of this service he was made an as- 

 sistant professor and by 1878 had been given 

 rank as a full professor. In 1886 he became 

 director of the Rogers laboratory and in 1907 

 was made head of department. It is the 

 threefold mantle of these responsibilities which 

 he wears to-day and which he now contemplates 

 laying aside. 



Such accumulated funds of loyalty to his in- 

 stitution, of prestige not only in its counsels 

 but in the scientific world at large, and such 

 skill of investigation and analysis as Professor 

 Cross has acquired, constitute a tangible for- 

 tune which might well be assessed only for its 

 large present values. Yet if one is to take his 

 career in review, there must be observed in 

 particular the contribution Professor Cross 

 made to the establishment of electrical engi- 

 neering as an independent department of mod- 

 ern scientific and technical training. In the 

 early eighties, some time before the wondrous 

 expansion in the practical uses of electricity 

 had generally been foreseen. Professor Cross 

 prophesied it and insisted on electrical studies 

 as part of his teaching in physics. He offered 

 them long before they were taken up by other 

 educators throughout the country, he developed 

 their technique and bore the brunt of a pio- 

 neer's labor. Later it was at his instance that 

 Technology introduced the first courses leading 

 to a degree in electrical engineering ever 

 offered in America. All through this develop- 

 ment, his influence made for the increasing use 

 and effectiveness of experiments in the illus- 



