952 



SCIENCE. 



[N. S. Vol. XIV. No. 364. 



the individual. I have in previous reports 

 made specific recommendations looking to 

 the establishment and maintenance of a 

 permanent force for these departments. I 

 renew these recommendations. The accom- 

 panying reports show the volume of busi- 

 ness in these departments for the year. 



THE PRIME VERTICAL TRANSIT AND THE 

 ALTAZIMUTH. 



Sir: In compliance with paragraph 

 twenty three of the regulations governing 

 the United States Naval Observatory, I re- 

 spectfully submit the following report of 

 the operations in my department during 

 the year ending June 30, 1901. 



Before proceeding to report upon the ob- 

 servations secured with the instruments I 

 desire to invite the attention of the superin- 

 tendent to the following extract from Sci- 

 ence for January 11, 1901, page 42 : 



" We find, also, that the total number of 

 separate observations with the prime verti- 

 cal transit was 164, less than one-half the 

 number of nights in the year, while those 

 with the altazimuth, used as a zenith tele- 

 scope, numbered a little more than the days 

 in the year. At the international geodetic 

 stations the observers are expected to make 

 about sixteen double observations on every 

 clear night." 



Attention is also invited to this extract 

 from the same publication, but of date Jan- 

 uary 4, 1901, page 4 : 



" There are. also intimations that some- 

 thing is wrong with the prime vertical tran- 

 sit, and altogether the impression made on 

 the reader is that, after seven years of 

 effort to equip the observatory with the 

 best instruments, it is doubtful whether 

 a single one of real importance, except 

 the great telescope, is in order for first- 

 class work." 



The writer of these editorials in Science 

 clearly indicates that his conceptions of the 

 amount of astronomical observing to be ob- 



tained with an instrument in the prime 

 vertical are absurd. 



Taking up the first extract, I wish to 

 answer it. I was, by orders of the Depart- 

 ment, as well as by yourself, detailed last 

 spring as an observer in one of the parties 

 sent south to observe the eclipse of the sun, 

 and for six weeks I was detached from the 

 instrument. 



From April 15 to May 1, I was directed 

 to give my whole time to preparing for ship- 

 ment the apparatus to be used in the eclipse. 

 From May 1" until June 1, 1900, I was at 

 Grif&n and Barnesville, Ga., engaged in 

 preparing for the phenomena just men- 

 tioned. In addition, I observed at both 

 places on fifteen nights, to determine their 

 latitude and longitude. 



The wisdom of the Observatory displayed 

 in having those two fundamental positions 

 determined is well illustrated by the mis- 

 fortune that came to an observer who went 

 to Africa. He trusted to an approximate 

 latitude and longitude, and found at the 

 instant of the eclipse he was entirely out- 

 side of the shadow line. 



If the writer of the above extract was 

 only superficially informed of the time 

 necessary to secure a complete observation 

 of a star across the prime vertical, he would 

 not have attempted to make a comparison 

 between the number of observations secured 

 during the same period with the prime 

 vertical and the zenith telescope. It will 

 take about four hours per night to observe 

 sixteen pairs of stars with the zenith tele- 

 scope, the number usually obtained by those 

 engaged in the variation of latitude work. 

 In the same time it is impossible for anyone 

 using the prime vertical to secure more than 

 four or five, and had the writer consulted 

 an astronomer he would have found that 

 out. 



During the past spring I observed prac- 

 tically all night on each in which the sky 

 was clear, and over a tour of observing of 



