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 conclusions can be drawn.  Errors of greater or less magnitude were thence unavoidable; at Cape Gloucester, where I quitted the East Coast, my longitude was 201/2’ greater than captain Cook’s chart—­at Cape York where the survey was again resumed, it was 581/2; and to incorporate the intermediate parts, it was necessary not only to carry his scale of longitude 201/2’ 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 in various places upon one or more of the above authorities, for differences between them were frequent and sometimes considerable, and in one instance alone a reduction of 12’ in the chart was obtained.  It is said in Hawkesworth (III, 202), “As soon as we got within side the reef (through Providential Channel) we anchored in nineteen fathom;” and afterwards (p. 204), that the channel, “bore E. N. E. distant ten or twelve miles.”  In the first chart the distance is 141/2 miles, and nearly the same in that which accompanies the narrative; but in the log book it is said to be 21/2 miles only, which corresponds with having anchored as soon as they got within the reef, and has been adopted.  In some cases it was not easy to make a choice between these different authorities; but I have commonly followed the narrative and log book when they were found to specify with precision, and they generally produced such corrections to the chart as brought the longitudes of places nearer to my positions.  Captain Cook’s track in Plates XI.  XII. and XIII. is laid down afresh from the log book; and many soundings, with some other useful particulars not to be found in the original chart, are introduced, for the benefit of any navigator who may follow the same route.

The reconstruction of the charts in the Atlas was done upon various scales, but that no error might escape unseen, the least was of ten inches to a degree of longitude; they were then reduced by Mr. Thomas Arrowsmith to four inches, this being thought sufficiently large for a general sailing scale; and each reduced sheet was scrupulously compared by me with the original before it went into the engravers hands, and the proof impressions with the drawing until no errors were found.  To those who may read this voyage with a view to geographical information, a frequent reference to the Atlas is earnestly recommended; for many particulars are there marked which it would have been tedious to describe, and should any thing appear obscure in the narrative the charts will generally afford an elucidation.