26 MEMOIRS OP THE NATIONAL ACADEMY OF SCIENCES. 



to be i*" ; that is, the time of high water water is 4'' later than the moon's trausit. The greatest 

 daily range was 1' 7" ; the least daily range was 0' 5". 



i 3. LONGITUDE OF CAROLINE ISLAND.— By Mr. Winslow Upton. 



The longitude of Caroline Island was determined by means of chronometers and from obser- 

 vations of moon culminations. The care of the chronometers was in the hands of Ensign Brown 

 from the time of leaving New York until March 24, after leaving Callao in the Hartford, and 

 in my hands for the rest of the voyage. The observations for time with the transit on Caroline 

 Island were ma<le by Mr. Peeston, as well as the observation of moon culminations. Tlie reduc- 

 tion of the work was assigned me ; this report therefore incorporates the work done by these 

 members of the party as far as it bears upon the determination of the longitude. 



longitude feom chronometers. 



The following chronometers were carried on the expedition : Negus, 1340, mean time; Negus, 

 1536, sidereal time ; Negus, 1589, sidereal time ; Hutton, 202, sidereal time; Bliss, 2876, sidereal 

 time. 



The first two were brought from the United States Naval Observatory with their corrections 

 determined at Washington. The third and fourth were brought from the ofQce of the United 

 States Coast and Geodetic Survey with their corrections undetermined. The fifth was brought by 

 Professor Holden, not running, and was started on the second day after leaving New York. The 

 corrections at the beginning of the voyage of the last three chronometers were obtained by com- 

 parison with the first. On the Hartford regular comi>arisons were made with the chronometers 

 of the ship as follows: Bond, 233, mean time; Negus, 1288, mean time; Negus, 1065, mean time; 

 Wood, 425, mean time. For the greater part of tlie expedition nine chronometers therefore were 

 in use. On the Zealnndia, from Honolulu to San Francisco, comparisons were made with the two 

 chronometers of that ship, but were not used in the reductions. 



Throughout the journey ft'om New York to San Francisco daily comparisons were made of 

 the several chronometers. At New York observations of the time-ball checked the running of 

 1340 and 1536 from Washington. At Aspinwall the local time was obtained by sextant observa- 

 tions, and by comparison with the chronometer of the Royal Mail steamer Medway, Fletcher., 

 1608. At Callao no observations were made, the local time adopted depending upon comparisons 

 with the Hartford and^values deduced from the rates of the chronometers. At Caroline Island 

 sextant observations were made until the mounting of the transit. At Honolulu sextant observa- 

 tions were made, and at San Francisco comparisons at the observatory of the United States Coast 

 and Geodetic Survey with the chronometer of the transit of Venus party under the charge of Mr. 

 Edwin Smith, the correction of which was determined by transit observations made by Prof. H. S. 

 Pritchett. At Honolulu chronometers 202 and 1589 were left behind, and for the voyage from 

 Honolulu to San Francisco but three chronometers in consequence were avaiLable. The following 

 table contains the adopted chronometer corrections at the various places enumerated above. The 

 chronometers are designated by their numbers, and the corrections are in Greenwich mean or 

 sidereal time. Nos. 202 and 1589 were regulated to Washington time, but were set by Mr. Preston 

 at Caroline Island to local sidereal time, which explains the change in the corrections. Nos. 1536 

 and 2786 were regulated to Caroline sidereal time. The others were running on Greenwich mean 

 time. 



