July 27, 1900.] 



SCIENCE. 



127 



tronomical photographs has included work 

 upon Eutherfurd negatives and upon nega- 

 tives made at Helsingfors, Finland, and at 

 the Cape of Good Hope. In connection with 

 the Eutherfurd plates, the observatory has 

 just published Dr. W. C. Kretz' paper on the 

 ' Stars in the Coma Berenices Cluster. ' This 

 paper was offered by Dr. Kretz last year as 

 his dissertation for the degree of Ph.D. It 

 will be distributed very soon. Dr. G. N. 

 Bauer's paper, also a dissertation for the de- 

 gree of Ph.D., contains a determination of 

 the parallax of ij. Cassiopeise from Euther- 

 furd measures of position angle. It is now 

 in course of publication, as is also a paper by 

 Professor Jacoby on the 'Pleiades.' This 

 latter contains the results of farther com- 

 putations that have been made in recent 

 years, using the same Eutherfurd measures 

 discussed in Professor Jacoby's former paper 

 on the ' Pleiades,' published in 1892. The 

 new discussions bring out the excellence of 

 Eutherfurd's work even more clearly than 

 before. Several other sets of Eutherfurd 

 star plates have been measured and re- 

 duced, but it has not yet been possible to 

 prepare the results for printing. 



An attempt was made last year to photo- 

 graph the November meteors, and one trail 

 was secured by Mr. C. A. Post and Profes- 

 sor Eees, at the former's observatory in 

 Bagport. 



Dr. Caroline E. Furness has completed 

 the discussion of four photographs of the 

 stars immediately surrounding the north 

 pole of the sky. These photographs were 

 made at Helsingfors some years ago, and 

 measured at the Columbia University ob- 

 servatory. Dr. Furness has deduced from 

 these measures a photographic catalogue of 

 precision including the stars within one de- 

 gree of the pole, and has been able to show 

 also that the optical distortion of the Hel- 

 singfors telescope is coniined within very 

 small limits, so far as such distortion de- 

 pends on position angle. These researches 



are in course of publication by the observa- 

 tory of Vassar College, and have formed 

 the subject matter of a dissertation for the 

 degree of Ph.D., conferred upon Miss Fur- 

 ness this year at Columbia University. 



A similar series of negatives of the south 

 pole was made some years ago at the Cape 

 of Good Hope, and these have been in 

 course of measurement during the past 

 year at Columbia. It is hoped that they 

 can be completed during the present sum- 

 mer, and that the results can be computed 

 and published within a year. 



The attempt to secure an independent 

 determination of the constants of nutation 

 and aberration by photographing close polar 

 star trails has made considerable progress. 

 A special ' fixed ' polar telescope has now 

 been mounted by Dr. Donner in a suitable 

 new building at Helsingfors, at which place 

 it is intended to make the observations, in 

 order to take advantage of the high altitude 

 of the pole, and the consequent diminution 

 of atmospheric refraction. This fixed tele- 

 scope will be used with the object glass of 

 the present Helsingfors astro-photographic 

 refractor. We shall thus secure the im- 

 portant adventage of using a glass whose 

 optical distortion has been most carefully in- 

 vestigated . It is hoped that the actual work 

 of making the negatives can begin at Hel- 

 singfors as soon as the nights become a little 

 longer, and that measurements can com- 

 mence at Columbia before the year is out. 



Photometric Observations of the Asteroid Eros : 



By Henry M. Paekhuest. 



My simple formula for the diminution of 

 the light of an asteroid in proportion to the 

 angle at the asteroid between the sun and 

 the earth, seems to be substantiated by Pro- 

 fessor Miiller, within ordinary limits, but 

 the new asteroid Eros extends the angle so 

 far as to create uncertainty. For the old 

 asteroids the extreme value of this angle 

 seldom exceeds 30 degrees ; whereas its 



