844 



SCIENCE. 



[N. S. Vol. VIII. No. 207. 



sixty years ago, when it was a disputed ques- 

 tion whether the polar or equatorial diam- 

 eter of the earth was the longer, the French 

 Academy decided to make one supreme 

 effort to settle the point. To this end, two 

 arcs were measured : one on the equator 

 (now known as the Peruvian arc, although 

 it is really in Ecuador) ; and the other in 

 Lapland, as near the pole as possible. 

 These two arcs, confessedly inaccurate in 

 the light of modern geodesy, have been em- 

 ployed continually in the determination of 

 the earth's figure. Situated as they are, 

 near the extremities of the quadrant, their 

 influence is great on the shape deduced, so 

 that one of the pressing needs of the day in 

 the measurement of the earth is a i-edetermi- 

 nation of their lengths. France having 

 made the first measure, by common consent, 

 this country should be given the first chance 

 to repeat the equatorial work. At the con- 

 ference in Paris in 1889 the matter was 

 brought up, but was left to be disposed of 

 by France. Efforts were made to accom- 

 plish the task, the oflBcers were in part desig- 

 nated, and arrangements for cooperation by 

 the government of Ecuador were completed. 

 At this juncture the revolution broke out in 

 Ecuador and the matter came to an untimely 

 end. It is now proposed to make a recon- 

 naissance during the summer of 1899, report 

 the results thereof to the Paris conference 

 of 1900, and then decide definitely on the 

 plans of final measurement. It is univer- 

 sally conceded that France should be given 

 the first chance to act, not alone because the 

 first measure was made by her, but also be- 

 cause the conference of 1889 relinquished in 

 her interest further consideration of the 

 subject. 



The Eussians and Swedes, in a quiet sort 

 of way, are measuring an arc between the 

 parallels of latitude 77i° and 81i° in Spitz- 

 bergen. The triangulation will require two 

 summers and part of one winter, and will 

 cost 100,000 Kronen ($27,500), exclusive of 



cost of vessels furnished bj' the governments. 

 The field work will be finished in 1900 and 

 the computations two years later. Fifty 

 stations will be occupied. The sides range 

 in length from ten to one hundred and thirty 

 kilometers, and the bases, of which there 

 will be only two, are to be measured with 

 with Jaederin's steel tape line, 20 meters 

 long. 



The difierence of longitude between Paris 

 and Greenwich comes up again for investi- 

 gation. This question has been a sort of 

 thorn in the side of European geodesy for 

 ten years. In 1872 the United States 

 Coast Survey made a determination, in 

 order to have a check on the telegraphic 

 longitude of our trigonometric points as de- 

 termined independently from Paris and 

 Greenwich. This was followed in 1888 by 

 two separate determinations, one on the 

 part of England, the other on the part of 

 France. The results differed by more than 

 two-tenths of a second. Our own result 

 falls between them, and it is a matter of 

 congratulation to all Americans that the 

 best determination to the present day of 

 this important quantity is the work done 

 by the United States Coast Survey, while 

 incidentally checking its own longitude de- 

 terminations. Nothing was done to im- 

 prove the agreement until 1892, when the 

 work was repeated, both by the French and 

 English, only to yield results practically 

 identical with those previously obtained, sO' 

 the unfortunate discrepancy still remains^ 

 and the five direct determinations already 

 made leave the work in an unsatisfactory 

 condition. Six indirect results may be had 

 from combinations of general European 

 work, through Brest, Vienna, Berlin, Bonn 

 and Leiden, the mean of which gives the 

 same result as the mean of the direct de- 

 terminations. Nothing seems to remain^ 

 therefore, but to studj' the conditions of the 

 work of 1888 and 1892, and reconcile, if 

 possible, the outstanding' difference. The 



