October 



1904.] 



SCIENCE. 



469 



By the transmission time of a signal over a 

 cable is meant the time that elapses from the 

 instant the record is made on the slip at the 

 sending station to the instant the record is 

 made on the slip at the receiving station. 

 These times as determined from sending sig- 

 nals in both directions over the four cables 

 are given in the last column of the following 

 table. The other data in the table have been 

 kindly furnished by Mr. G. G. Ward, the 

 vice-president and general manager of the 

 cable company. 



The following are the differences of longi- 

 tude corrected for personal equation as de- 

 termined over these four cables : 



The San Francisco station is 8^ 9™ 48*^.813 

 ± 0^.056 west of Greenwich (see ' The Longi- 

 tude Net of the United States and its Con- 

 nection with that of Europe, 1866-1896,' 

 Appendix 2, Coast and Geodetic Survey Re- 

 port, 1897, and also * The Transcontinental 

 Triangulation,' pp. 820 and 826, Coast and 

 Geodetic Survey Special Publication, 1900). 

 The Manila station is 0^.224 west of the dome 

 of the Manila Cathedral, which is the accepted 

 point of reference in Manila. Combining 

 these with the above differences of longitude, 

 we have the following longitudes: 



h m s s 



Honolulu Transit west of Greenwich 10 21 27.752 + 0.0.5 

 Midway Transit west of Greenwich 11 49 30.9.51 + 0.057 



Guam Transit east of Greenwich 9 38 35.465 ± 0.068 



Manila Cathedral dome east of Greenwich 8 03 52.425 + 0.059 



Comparisons with former determinations of 

 the longitudes of the several stations. 



Honolulu. — In a former issue of this paper* 

 " November 6, 1903. 



an elaborate discussion of former determina- 

 tions of the longitude of Honolulu was given 

 by Mr. J. F. Hayford, of the Coast and Geo- 

 detic Survey, to which the reader may refer. 

 We will give here only the most reliable one. 

 In 1874 Captain G. L. Tupman, Eoyal Marine 

 Artillery in charge of the British Transit of 

 Venus Expedition of that year, determined the 

 longitude of his station by seven results from 

 occultations of stars by the moon, fifty-two 

 results from observations of moon culmina- 

 tions and sixty results from the observations 

 of zenith distances of the moon combined with 

 the observed culminations and zenith distances 

 of well-known stars. His result officially com- 

 municated to' the Hawaiian government is 

 lOh 3im 27S.2. 



The longitude determined by- the Coast 

 and Geodetic Survey by the cables referred 

 to the same point is iCi 31°i 27^.236, a re- 

 markably close agreement. 



Midivay Islands. — These islands were dis- 

 covered by Capt. ]Sr. C. Brooks in the Gamhia, 

 July 5, 1859. In 1867 Capt Eeynolds, U.S.N., 

 in the Laclcawana, visited the islands and gave 

 the longitude of the north point of the larger 

 island as: 



Longitude 177° J8' 20" west, 

 h m 3 

 11 49 13.3 



In 1900 a survey was made of the islands 

 by the officers of the U. S. S. Iroquois, under 

 the command of Lieut. Commander C. F. Pond. 

 The Hydrographic Office Chart No. 1951 is 

 based upon this survey and the longitude given 

 for the point marked Observation Spot is : 



Longitude 177° 21' 30" west, 

 h m s 

 11 49 26 west. 



The longitude determined by the Coast and 



Geodetic Survey by the cables referred to the 



same point is : 



Longitude 177° 22' 46."4 west, 

 h m s 

 11 49 31.091 west. 



Guam Island. — In 1819 M. de Freycinet in 

 the French corvettes L'Uranie and La Physi- 

 cienne made a survey of the southern jsart of 

 the Mariana or Ladrone Islands and gave the 

 longitude of Fort Santa Cruz in the harbor of 

 San Luis D'Apra, Guam Island, as : 



