Page image

3

C.—2

the English party, being stationed at Burnham, Canterbury, and Mr. E. Smith and the American party in the Domain-grounds of Auckland City. To guard against the accidents of weather Colonel Tupman invited the co-operation of all observers who had the necessary equipment, so that if observations failed at one station they might be obtained at another. The Survey Department was enabled, through the kindness of private gentlemen possessing good telescopes, and from the resources of the department itself, to equip stations at New Plymouth, Bidwell's (Wairarapa), "Wellington, and Christchurch, at all of which the observation of internal egress was most successfully accomplished. The actual observation of the transit being a record of the instant of the apparent meeting or contact of the limb of Venus with that of the sun, it becomes of the utmost importance to have the true sidereal or mean time determined with the greatest accuracy, and that the observers at different stations either all keep the same time or have the means of knowing their differences from one standard clock. With the view of securing this concert among the New Zealand observers, the greater number of them had their stations placed in telegraphic circuit. Time-signals were distributed from Colonel Tupman's station at Burnham to observers in the Middle Island, and from Survey Observatory, Mount Cook, Wellington, to several of the observers in the North Island and in Nelson. Another essential is the correct knowledge of the longitude of the stations. Exchange of signals for this purpose were made between Burnham and Auckland, Burnham and Wellington, Wellington and New Plymouth, Wellington and Bidwell's, Wairarapa. These New Zealand stations are therefore well connected together; and, as Colonel Tupman has had exchange of time-signals through the cable with Sydney, and the gaps in the exchange of time-signals between Sydney and Greenwich have been also completed since the transit, it will be seen that there is now an unbroken line of longitude determination, binding the various stations together. The observations of internal contact at the stations enumerated hereafter were not attended with any phenomena of black-drop or pear-shaped appearance of planet or other perplexing phases such as were anticipated from the records of some of the observers of former transits. The first decided appearance, as seen by me through the 5-inch equatorial telescope at Mr. King's observatory, at Boulcott Street, Wellington, was a rapidly-forming haze between the limbs of Venus and the sun, through which, as the planet made its way, there seemed a disturbance on the limb of the sun. This lasted for nine seconds previous to the geometrical contact by the apparent touch of the two black edges, which phenomenon was instantaneous ; there could be no doubt about it. Prom that instant a broadening band kept forming as the planet overlapped the edge of the sun. The external contact, an observation of very secondary importance to that of internal contact, and to which no great value is attached, was also very well defined; there was no clinging to the edge of the sun at parting. The planet went off quite uniformly. The only difficulty in the observation was to name the exact second that the blunt cusps of Venus met as they gradually approached each other on the edge of the sun. The time noted for this observation might be uncertain to two seconds. The decimal of a second given in the table hereafter arises from applying the clock-correction to the recorded time. The various observers enumerated had each two assistants, one to count aloud the second-beats of the clock or chronometer, the other to note the minutes and the times given by the observer. In this manner the records of each observer were made, and his report of phenomena written before consultation with others, so as to guard against error or bias. The weather was favourable for observation at all the stations ; at Wellington especially so ; the sky being bright and clear, no wind, and a steady atmosphere. There was no tremor or boiling of the sun's limb at the time of observation. With a power of 250, the definition was excellent in the telescope at Boulcott Street. The instrument is a splendid 5-inch equatorial telescope, 80 inches focal length, by Grubb, of Dublin. It was recently imported by Mr. T. King, and very generously lent by him for the observation. At Mount Cook Observatory, Wellington, Mr. C. W. Adams observed with a 4-inch telescope and a power of