0 
PREFACE. 
vir 
perplexed; the discoveries and examinations of former navigators 
which come within the sphere of each sheet, are therefore incorpo- 
rated with, or added to mine, but so marked as to be distinctly 
known. In making the combination, alterations in their longitudes 
were frequently necessary to agreement ; and that they might be 
made with every regard to accuracy, the charts of the former 
discoveries were compared with the astronomical observations, 
narratives, or manuscript journals, when such could be had, and the 
alterations introduced where there seemed to be the best authority. 
This has been done with the charts of the east coast of New South 
Wales, published by Mr. Dalrymple from the manuscripts, as it 
should appear, of captain Cook ; and since it may be thought pre- 
sumptuous in me to have made alterations in any work of so great 
a master, this case is selected for a more particular explanation. 
Time keepers were in their infancy in 1768, when captain Cook 
sailed upon his first voyage, and he was not then furnished with 
them ; his longitude was therefore regulated only by occasional 
observations of lunar distances and some few of Jupiter's satellites, 
which even in the present improved state of instruments and tables, 
require to be connected by time keepers before satisfactory conclu- 
sions can be drawn. Errors of greater or less magnitude were 
thence unavoidable ; at Cape Gloucester, where I quitted the East 
Coast, my longitude was 2oi' greater than captain Cook's chart,— at 
Cape York where the survey was again resumed, it was 58^; and 
to incorporate the intermediate parts, it was necessary not only to 
carry his scale of longitude aoi' more west, but also to reduce the 
extent of the coast. The chart was compared with the narrative 
and chart in Hawkesworth, and the log book of the Endeavour 
with them all ; when it was found that reductions might be made 
m various places upon one or more of the above authorities, for 
differences between them were frequent and sometimes considerable, 
