TRANSIT OF VENUS, 1874. 



PART I. 



EXPEDITION TO THE HAWAIIAN (SANDWICH) ISLANDS. 



SECTION I. HONOLULU. 



I'agc- 

 VOYAGE, PERSONNEL, SITE, INSTRUMENTS, AND GEOGRAPHICAL DETERMINATIONS : 



Voyage and Establishment at Honolulu 5 



Personnel 6 



Site 7 



The Transit Clock and Transit Instrument . ~ . . 9 



Equatorial Intervals and Error of Level 11 



Error of Collimation 12 



Error of Azimuth and Meridian Mark .',.'..... 13 



Transits of Stars and of the Moon . . , ..,-.' . . , . . . . . 15 



Relative Personal Equations 16 



Adopted Errors and Rates of the Transit Clock . . . , . ...... . . 17 



The Altazimuth Instrument ,...,..'.... 18 



Intervals of Wires ...... 19 



Runs of Micrometers, and Position of the Altazimuth Pier .... 4 .... 2O 



The Altazimuth Clock . . . _ . . . . . 20 



Latitude of the Altazimuth Pier . . . ' . ; . . . 20 



Observations for Co-latitude, Refractions, Zenith Points . . . . i ... , 21 



Summary of Co-latitudes . . . 22 



Longitude of the Station at Apua . . 22 



Longitude from Meridional Transits of the Moon . . . . ^ , . . .... . 22 



Summary of Meridional Results ............ 23 



Longitude from Observed Zenith Distances of the Moon -. 24 



Summary of Results from Zenith Distances . . . .... . . . . . 27 



Longitude from Occultations of Stars by the Moon 27 



Comparisons of Chronometers, and Observations of Occultations ...;.... 2S 



Calculation of Longitude from Occultations 29 



Summary of Results for Longitude, from all sources . . ' 30 



CHRONOMETRIC CONNECTIONS WITH KAILUA (HAWAII OR OWHYHEE), WITH WAIMEA 



(KAUAI OR ATOOI), AND WITH SAN FRANCISCO (CALIFORNIA) : 



List of Chronometers 31 



Detail of Voyages with the Chronometers ..-.'." .'"V" 32 



Results for Difference of Longitude, and Personal Equations . . .;..'.,. . . 35 



For Honolulu and Kailua . . . . . . J . . 35 



For Honolulu and Waimea 35 



Detail of Voyage to San Francisco, and Mode of Observation ,. . ... ., . . ^ . , 3t> 



Result derived from San Francisco ..'.'. 37 



OBSERVATION AT HONOLULU OF THE INGRESS OF VENUS, 1874, DECEMBER 8. 



REPORT OF CAPTAIN G. L. TUPMAN, R.M.A. : 



Personal Arrangements, and Telescopes '. . 38 



Reflection Eye-pieces, and Double-image Micrometers 39 



Clock, Arrangement of Spectroscope for the Observation of External Contact ... 40 



Observation of commencement of Ingress, Measures of Cusps 41 



Measures of Venus' Diameter, and of Cusps before Internal Contact 42 



A 2 



