60 Transactions. 



Norfolk ; hence Southport (Queensland), Doubtless Bay (New 

 Zealand) and Suva (Fiji) are free from personal equation. 



Personal - equation observations were, however, made at 

 Ottawa by the two observers using the same clock and deter- 

 mining its correction at the same time on the same stars with 

 the two transit instruments, and the resulting difference of per- 

 sonal equation, 0"124s., applied to Fanning and Norfolk. 



Southport was comiected with the observatories at Sydney 

 and at Brisbane, and similarly Doubtless Bay with the observa- 

 tory at Wellington. Personal-equation observations were made 

 between the respective observers. 



It was on the 29th September, 1903, that the first satisfactory 

 clock exchange was had with Sydney, and so this night may be 

 considered as the one when for the first time longitude from the 

 west clasped hands with longitude from the east, and the first 

 astronomic girdle of the world was completed. The immediate 

 reasons for the first telegraphic connection in longitude between 

 Australia and the prime meridian, Greenwich, were (1) with a 

 view of confirming the position of the eastern boundary of the 

 Colony (now State) of South Australia, 141° E. ; (2) for obtain- 

 ing the longitude of stations to be occupied for observing the 

 transit of Venus in 1882. To attain this end connection was 

 made astronomically between Sydney, Melbourne, Adelaide, 

 Port Darwin, and Singapore. A connection was made, too, 

 between Sydney and Wellington. All Australian and New 

 Zealand longitudes at present rest on the position of Singapore 

 as accepted in 1883, which then, quoting from the Government 

 report for 1886 of South Australia, " had twice been telegraph- 

 ically determined — first in 1871 by Dr. Oudeman, of Batavia, 

 and Mr. Pogson, of Madras, and more recently by Commander 

 Green, United States Hydrographic Department." The de- 

 terminations of the latter were accepted. It may be remarked 

 that at this time the Thomson (Lord Kelvin) recording- siphon 

 had not yet been introduced, and that the clock exchanges 

 between Port Darwin and Singapore over the cable were made 

 by use of the deflecting mirror or reflecting galvanometer, already 

 spoken of, a method involving more or less uncertainty in noting 

 by " eye and ear " the movement of the mirror and the instant 

 of time of its occurrence. 



Singapore was dependent in position upon Madras, the initial 

 meridian for the great trigonometrical survey of India. 



For over a century observations have been taken from time 

 to time to determine the longitude of Madras. The early ones, 

 before the advent of cables and telegraphs, were dependent 

 mostly on lunar observations, some on Jupiter's satellites. In 

 1891 the Survey of India had not adopted the then best value, 

 so that at the International Geographic Congress held at Berne 



