470 



SCIENCE. 



[N. S. Vol. XX. No. 510. 



144° 39' 45" east, 

 h m s 

 9 38 39 east. 



(See Findley's ' ISTortli Pacific Directory,' 

 p. 800.) 



In 18Y5 the island was visited by Capt. 

 EJQorr, of the German Navy, in the ship 

 Hertha. The longitude of Fort Santa Cruz 

 was determined to be : 



144° 39' 30" east, 

 h m s 

 9 38 38 east. 



See Armalen HydrograpMe, 1875, p. 284, and 

 also of geographical positions compiled by 

 Lieut. Commander Green and published by the 

 Hydrographic Office, F. S. N., 1883. 



In 1899 the officers of the U. S. S. Yosemite 

 made a survey of the harbor of San Luis 

 D'Apra. They built a concrete pier on Fort 

 Santa Cruz and determined its longitude by 

 transit observations and the transportation of 

 chronometers back and forth from Yokosuka, 

 Japan. The longitude of this pier as com- 

 municated by the hydrographic office is : 



Longitude 144° 39' 21". 45 east, 

 b m s 

 9 38 37.43 east. 



The longitude determined by the Coast and 

 Geodetic Survey by the cables referred to the 

 same point is : 



Longitude 144° 39' 42".15 east, 

 li m s 

 9 38 38.81 east. 



Manila. — Two former telegraphic determina- 

 tions of the longitude of Manila can be de- 

 duced, one via Madras, India, and the other 

 via Vladivostock, Siberia. 



The longitude of Madras has been deter- 

 mined by five independent series of observa- 

 tions and a resume of them has been given by 

 Capt. Burrard in Appendix No. 2, Vol. XVII., 

 of the ' Great Trigonometrical Survey of In- 

 dia.' They are as follows : 



h m s s 



Series ^ 5 20 59.750 ± 0.155 1874-5 and 1881-2. 



.B 5 20 59.010 ±0.163 1874. 



C 5 20 69. 137 + 0.022 1876, 1881, 1892^-6. 



il 5 20 .59.223 ±0.127 1874-7. 



.B 5 20 69,421 ±0.123 1884-7. 



Series A is via Pulkowa, Moscow and 

 through Siberia to Vladivostok by the Eus- 

 sians and thence to Madras by the U. S. Navy. 



As the series will be used for the deduction of 

 the longitude of Manila direct, it will not be 

 considered in the determination of the longi- 

 tude of Madras. 



Series B, D and E were mostly determined 

 by the parties who went out to observe the 

 transit of Venus in 1874, and it is stated that 

 the observations were not conducted with the 

 refinement necessary for the determination of 

 fundamental longitudes. It therefore seems 

 at the present that series C must be considered 

 the only reliable determination of the longi- 

 tude of Madras. It is made up of ten differ- 

 ences of longitude in which personal equation 

 was eliminated by the exchange of observers 

 or by special observations. The observers 

 were also so placed that in the final longitude 

 of Madras personal equation would be elimi- 

 nated. One link in this series is the difference 

 of longitude between Potsdam and Greenwich 

 and this was redetermined in 1903 by the Ger- 

 mans in most refined manner and the result 

 increases the longitude of series by 0^.098. 

 This increased result will be used in the de- 

 duction of the longitude of Manila. 



The difference of longitude between Pul- 

 kowa-Greenwich was redetermined by two 

 steps, Pulkowa-Potsdam and Potsdam-Green- 

 wich, by the Germans in 1902-3. This work 

 supersedes the older determinations and will 

 be here used. The difference of longitude Vla- 

 divostok-Pulkowa is made up of thirteen dif- 

 ferences of longitude by the Russians. In all 

 the work between Vladivostok and Greenwich 

 personal equation was eliminated as in the 

 case of Madras. 



In 1881-2 the differences of longitude of 

 Vladivostok-Manila and Manila-Madras was 

 determined by officers of the U. S. Navy. The 

 entire work consists of ten differences of longi- 

 tude. Seven of them are involved in the dif- 

 ference of longitude Vladivostok-Manila and 

 four in the difference of longitude Manila- 

 Madras. In this work the differences of longi- 

 tude are not corrected for personal equation 

 and no information as to the value of personal 

 equation of the observers that can now be used 

 can be found. The endeavor was made to so 

 place the observers that personal equation 

 would be eliminated as far as possible in the 



