July 26, 1895.] 



SCIENCE. 



101 



a position relative to the proper mo- 

 tion of yy Cassiopeise as to be most largely 

 aifected by any error in the assumed value 

 thereof. Moreover, the value of +."15-t 

 obtained by Struve has received a much 

 larger share of credence than the circum- 

 stances connected with obtaining it would 

 warrant — Struve himself saying of it: "la 

 plus grande difticulte se rencontra dans les 

 observations de vj Cassiopese a cause d'une 

 distance de 5' pour I'etoile de comparison, 

 distance qui atteint deja les limites extremes 

 de la bonne visibilite dans le champ de no- 

 ire lunette." This is incidentallj^ referred 

 to by the author (page 305), where refer- 

 ence is given also to a remark, not verj- 

 dissimilar, made bj' Socoloff relative to 

 Schweizer's observations. Thus it may be 

 seen that the want of near-by stars renders 

 the determination of the parallax of this 

 star very difficult, especially by micrometric- 

 al observations; and though this difficulty 

 is considerably lessened by the larger field 

 of the Rutherfurd photographic plates, j-et 

 even now stars farther from the centre of 

 the plate than would have been desirable 

 under more favorable conditions had to be 

 chosen. This seems not to have vitiated 

 the result, for the values of parallax ob- 

 obtained from the separate pairs are, with 

 one exception, accordant within the limits 

 of their probable errors. This exception 

 may be due to a parallax or, not impossi- 

 bly, to a proper motion of one or other of 

 the comparison stars. This uncertainty, 

 and the fact that the pairs g, h and i, j were, 

 as the writer believes, included more to 

 throw light upon the presence or absence of 

 film-distortion than upon the parallax, has 

 infiuenced Dr. Davis to prefer the first of 

 the two values he publishes, namely: 



^ = + 0.''443 ± 0.'^038 from three pairs, 

 the other value being 



= -|- 0.''465 ± 0.''034 from six pairs. 

 Using the fii'st value, therefore, and the 



elements of this binaiy system as given by 

 Dr. See in Ast. Journ. 34.3, it is interesting 

 to note that the distance of this star from 

 the earth is about seven and one-third 

 ' light years ' and that the combined mass 

 of Eta and its companion is only .175 as 

 great as the mass of our sun, and that the 

 relative orbit in which these two stars re- 

 volve about this common centre of gravity 

 is very nearly equal to that in which the 

 planet Neptune circles about the sun. 



THE MARINE BIOLOGICAL LABORATORY. 



In the prefatory note to the biological 

 lectures delivered at "Woods HoU, 1894, Pro- 

 fessor Whitman writes as follows : " When 

 the first volume of these lectures was offered, 

 in 1890, their continuance as an annual 

 publication was thought of onlj^ as a pos- 

 sibility ; it was not promised, nor, indeed, 

 suggested. The usefulness of such lectures 

 had only been tested by a single summer's 

 experience ; and, although it was certain 

 that they served a good purjwse in the work 

 of the laboratory, the advisability of pub- 

 lishing them was doubtful. While the re- 

 ception accorded to the two volumes already 

 issued indicates that it would not now be 

 presumptuous to announce the hope of con- 

 tinuing them, it would be rash to promise 

 this in the present state of uncertainty re- 

 garding the future of the laboratory. The 

 laboratory is an experiment to test the ex- 

 tent of our need and the possibility of 

 securing general cooperation. It has fur- 

 nished a demonstration in both these re- 

 spects; but it remains to be seen whether 

 this will suffice to bring to it the necessary 

 foundation of a large endowment. Special 

 thanks are due to those who, in reviewing 

 the ' Biological Lectures,' have called at- 

 tention to the nature and purpose of this 

 experiment and to the high importance of 

 the end proposed. The project appeals, 

 not for government support, but to private 

 munificence, and every authoritative con- 



