TERRA AUSTRALIS. 
149 
Wellesley’s Islands.'] 
No. 543, - 140 s 6' 35",a east. 
520, - 139 47 4 3 > 3 
No. 520 therefore differed very little to the east of the lunar observa- 
tions, and the first day’s rate was almost exactly the same as that 
with which we had quitted Upper Head; whilst No. 543 differed 
greatly, both in longitude and rate. A similar discordance had been 
noticed at the Cumberland Island, marked 1 2, twenty days after 
leaving Upper Head ; No. 520 then differed only i / i",q from the 
survey, but No. 543 erred 7' 2", 2 to the east. I have therefore been 
induced to prefer the longitude given by No. 520, to the mean of 
both time keepers ; and accordingly, the positions of places before 
mentioned or laid down in the charts, between Upper Head and 
Sweers’ Island, including Torres’ Strait, are from this time keeper 
alone ; with such small correction equally proportioned, as its error 
from the lunars, 2' 50" ,2 to the east in fifty-two days, made necessary. 
No. 543 had undergone some revolution on the passage, but 
seemed at this time to be going steadily ; whereas No. 520, which had 
kept its rate so well, now varied from 18", 79 to 25" ,39, and ceased 
to be entitled to an equal degree of confidence. 
Mean dip of the south end of the needle, observed 
upon the west point of Sweers’ Island, - 44 0 27' 
Variation of the theodolite in the same place, - 4 7 E. 
D°. of the surveying compass in the Road, 2 0 28' 
with the ship’s head E. N. E., and 4 0 30' with the 
head northward; the mean corrected to the 
meridian, will be - - - 4 3 1 
In bearings taken on the east side of Bentinck’s Island, the varia- 
tion appeared to be a full degree greater than on the west side of 
Sweers’ Island. 
The tides in the Investigator’s Road ran N. N. E. and S. S. W., 
as the channel lies, and their greatest rate at the springs, was one 
mile and a quarter per hour; they ran with regularity, but there was 
only one flood and one ebb in the day. The principal part of the 
1802. 
November. 
