166 



SCIENCE. 



[N. S. Vol. XI. No. 266. 



he was not altogether unmindful of the fact 

 that he would be erecting a monument 

 to himself which will endure as long as 

 science is cultivated. Let us hope that 

 these expectations may be realized with the 

 fullest measure of success. 



J. L. WORTMAN, 



Curator Dept. Vertebrate Pateontology . 



AN INTERNATIONAL PLAN FOB THE FUTURE 

 STUDY OF THE VARIATION OF LATITUDE. 

 Up to the present time the study of the 

 variations of latitude, first observationally 

 proved by Dr. Kustner, of Berlin, and de- 

 veloped by the investigations of Dr. Chand- 

 ler, has been the result of the work of ob- 

 servers who have been specially interested 

 in this subject. 



The stations have not been well distrib- 

 uted for a thorough investigation of the in- 

 teresting problem, because they have, as a 

 rule, been centered near large observatories 

 dealing with other astronomical matters, 

 when they should be less in clusters, and 

 spread over larger but uniform arcs of 

 longitude. 



The International Geodetic Association 

 in the year 1898 formulated a plan which 

 went into operation on January 1, 1900. 

 The aim of the Association has been to put 

 in service four stations, on the same parallel 

 of latitude, and as well distributed around 

 the earth as possible. 



The four stations chosen, their latitude 

 and the longitude east or west from Green- 

 wich are as follows : 



Mizusawa, Japan, Lat. 39° 08' 07", 141° E. L. 



Carloforte, Italy " 39° 08' 12", 9° 



Gaithersburg, Md. " 39° 08' 10", 77° W. L. 



Ukiah, Calif. " 39° 08' 12", 123° " 



As one second of arc expresses about 100 

 feet for differences of distance near the 

 above latitude, it will be seen that all the 

 stations are within the limit of 500 feet of 

 being on the same parallel line. 



Professor Porter's observatory at Cincin- 



nati, Ohio, happens to be very near the 

 chosen latitude, and he will also engage in 

 the work, having volunteered to do so. 



It is also expected that a station will be 

 established by the Russian government near 

 a city called Tcharjui, and its longitude is 

 64° east. This observing station is espe- 

 cially important, for it places one between 

 Mizusawa and Carloforte, and 187° from 

 Ukiah. 



In the past, many of the astronomers who 

 have given for the use of the student the 

 data necessary for a discussi(m of the varia- 

 tion of latitude, have made their observa- 

 tions conform to obtaining a correction to 

 the Constant of Aberration from the same 

 material. 



The International Association intends 

 that the series of observations which it has 

 just inaugurated shall be made for the dis- 

 tinct purpose of deriving the latitude varia- 

 tion only. 



Dr. Albrecht, of the Geodetic Service of 

 Germany, has been greatly iiiteres^ted in 

 formulating the plan of work, and has se- 

 lected twelve groups, each containing eight 

 pairs of stars. While this is in hand 

 Professor Helmert has advised that each 

 group contain two pairs of large zenith dis- 

 tance, as much as 60°. 



Professor Doolittle, at Philadnlphia, and 

 Dr. Davis and Professor Rees, of New York, 

 as well as other observers, have noticed in 

 a night's work often an anomalous condi- 

 tion presenting itself in which every pair 

 would clearly indicate an abnormal change 

 of as much as a second of arc from previous 

 and following night's results. 



Professor Helmert's idea is to intro- 

 duce these extra pairs to see if the cause 

 for these marked changes would be more 

 pronounced in those pairs of larger zenith 

 distance. 



All the stations are to use the zenith 

 telescope. The instrument has been made 

 by Wanschaff, and has an aperture of a 



