May 24, 1907] 



SCIENCE 



803 



facts. The conclusion was, therefore, 

 drawn that the subconscious need not be 

 taken into account in the psychological ex- 

 planation of optical illusions. 



Professor William F. Magie, of Prince- 

 ton, in a paper on the association theory of 

 solutions, expressed the view that the heat 

 capacity of electrolytic solutions and the 

 volumes of solutions can be satisfactorily 

 represented by a formula constructed on 

 the hypothesis that each undissociated 

 molecule of the solution associates with it- 

 self a group of water molecules. The heat 

 capacity of the solution is additive of the 

 heat capacities of these groups and of the 

 water lying outside of them. 



Dr. T. J. See, of Mare Island, Cali- 

 fornia, supplemented his former paper on 

 the theory of earthquakes which is pub- 

 lished in the Proceedings of the American 

 Philosophical Society, for 1906, by the 

 further examination of the temperature 

 and secular cooling of the earth, in which 

 he ^owed that the effects of contraction are 

 nearly insensible. The necessity of there- 

 fore abandoning old theories becomes more 

 patent. It is interesting to note that four 

 great writers of antiquity — Plato, Aristotle, 

 Strabo and Pliny — ascribe earthquakes to 

 the agitation of elastic vapors in the earth, 

 a confirmation of his own theory to which 

 Dr. See attaches considerable importance. 



Dr. Elihu Thompson, of Swampscott, 

 Mass., in his paper on .the progress of the 

 Isthmian Canal, gave, on the whole, a fa- 

 vorable account of the condition of the 

 work. The organization was pronounced 

 to be admirable, and this, taken together 

 with the successful work of sanitation 

 under the charge of Colonel Gorgas, gives 

 every reason to believe that the canal will 

 be finished in from eight to ten years. 



Among the geological papers, that of 

 Professor William B. Scott, of Princeton, 



giving illustrations of the restoration of 

 the Santa Cruz mammals, was the most 

 striking. Two other members of the geo- 

 logical department of Princeton, Messrs. 

 Sinclair and Farr, were represented by 

 papers, all touching on the results of the 

 Santa Cruz expedition of Princeton Uni- 

 versity. 



Another paper of general interest, that 

 by Bailey Willis on continental develop- 

 ment, was devoted to a discussion of the 

 various hypotheses to account for the cir- 

 cumstance that each of the two great con- 

 tinents is composed of distinct masses which 

 have tended to stand high in relation to 

 their surroundings. 



Professor Eric Doolittle's paper was on 

 two remarkable stars. One, discovered in 

 1882 by Hough, was for a time in danger 

 of being rejected, until in 1899 it was inde- 

 pendently rediscovered by See. The mo- 

 tion of this double star during the past two 

 years has been so rapid that already a 

 fairly good orbit can be computed. The 

 second pair is made up of two very faint 

 stars more than three and one half seconds 

 apart, a remarkable circumstance, for of 

 all the double pairs there are none at once 

 as faint and wide as this pair, except those 

 which are connected with very bright stars. 



The session on Thursday evening was of 

 a popular character, being held in Wither- 

 spoon Hall and devoted to South Africa. 

 The subject was divided between Professor 

 William B. Scott, of Princeton, and Pro- 

 fessor E. W. Brown, of Haverford. The 

 former spoke about the geology and geog- 

 raphy of South Africa, and the latter about 

 the scenery and people. Both lectures were 

 illustrated by stereopticon views. On the 

 conclusion of the lectures, a reception was 

 held by the president and council. 



At the close of the Saturday morning 

 session, balloting for new members was 



