856 



SCIENCE 



[N. S. Vol. XXXI. No. 805 



will hold a meeting once a year, are as fol- 

 lows: Pathological Department — Dr. William 

 H. "Welch, Baltimore; Dr. Theobald Smith 

 Boston; Dr. H, Gideon Wells, Chicago; Dr 

 Simon Flexner, New York. Clinical Depart 

 ment — Dr. James A. Miller, New York; Dr 

 Lawrason Brown, Saranac Lake, N. Y. ; Dr 

 Joseph Pratt, Boston; Henry Baird Pavill; 

 Chicago. Sociologic Department — Dr. Sam- 

 uel McC. Lindsay, New York; William H 

 Baldwin, Washington; Dr. Herman M. Biggs 

 New York; Dr. Samuel G. Dixon, Harris 

 burg. Pa. 



UNIVERSITY AND EDUCATIONAL NEWS 



Announcement is made of the receipt by 

 Western Reserve University of a gift of $250,- 

 000 by Mr. H. M. Hanna, as an addition to 

 the endowment of the medical department. 

 The income from this gift is to be largely 

 used in the clinical departments to enable the 

 school to put these departments upon a uni- 

 versity basis. 



Mh. J. Ogden Armoue has made a gift of 

 $70,000 to the Armour Institute of Technol- 

 ogy. 



Dr. Eoscoe Pound, who has successively 

 held chairs of law at the University of Ne- 

 braska, Northwestern University and the 

 University of Chicago, has been appointed 

 Story professor of law in Harvard University. 

 Dr. Pound was for many years director of the 

 Nebraska Botanical Survey and is well known 

 for his contributions to botany. 



Professor Alexander S. Langsdoef has 

 been appointed dean of the school of engineer- 

 ing of Washington University, to succeed 

 Professor Calvin M. Woodward. Professor 

 Langsdorf will continue in active charge of 

 the Department of Electrical Engineering. 



At the annual meeting of the regents of 

 the University of Nebraska Adjunct Professor 

 Walker and Adjunct Professor Pool, of the 

 department of botany, were promoted, with the 

 title of assistant professor of botany. Pro- 

 fessor Pool was made curator of the univer- 

 sity herbarium, also, and to Professor Walker's 



duties were added those of keeper of the 

 botanical library. 



At Cornell University instructors have been 

 appointed as follows : M. M. Goldberg, in 

 physics (promoted) ; Pred MacAllister, in 

 botany; H. W. Mayes and M. H. Givens, in 

 physiology and biochemistry (promoted). 



Dr. M. Verworn, professor of physiology 

 at the University of Gottingen has been 

 called to Bonn to succeed the late Professor 

 Pfliiger. 



DISCUSSION AND CORRESPONDENCE 



ON THE APPARENT SINKING OP SURFACE ICE IN 

 LAKES 



To THE Editor of Science : During the dis- 

 integration of the surface ice in a lake in the 

 spring it is a matter of common observation 

 by the natives that the ice suddenly appears 

 to sink, the surface of the lake becoming clear 

 in a few hours. The explanation of this ap- 

 parent anomaly was difficult to find until it 

 became clear to me as a result of a careful 

 study of the effect of water temperatures in 

 the St. Lawrence Eiver on the growth and 

 decay of ice. The ice sheet which forms on 

 the surface of quiet water becomes thicker on 

 the underside only by the conduction of heat. 

 The total thickness of the ice which will form 

 in a single winter depends not only on the 

 mean air temperature measured in degrees, 

 but on the mean water temperature measured 

 in thousandths of a degree above or below the 

 freezing point. 



From measurements made with my special 

 micro-thermometer I have found that the 

 temperature of the water just under the sur- 

 face ice in a lake or deep river is usually one 

 or two hundredths of a degree above the 

 freezing point, due to the lower layers of 

 warmer water. 



In the spring this temperature is consider- 

 ably higher and the effect of the warmer 

 underwater rapidly honeycombs the ice, thus 

 assisting the sun when the surface snow is 

 absent. In a flowing river the effect of wind 

 and current is to loosen the ice and it is soon 

 carried down by the stream. In a quiet lake 



