[V 
PREFACE. 
in the present advanced state of navigation, that they should not 
have been before discovered and a mode of preventing or correct- 
ing them ascertained, that my deductions, and almost the facts were 
distrusted ; and in the first construction of the charts I had feared 
to deviate much from the usual practice. Application was now 
made to the Admiralty for experiments to be tried with the compass 
on board different ships ; and the results in five cases being con- 
formable to one of the three laws before deduced, which alone was 
susceptible of proof in England, the whole were adopted without 
reserve, and the variations and bearings taken throughout the voy- 
age underwent a systematic correction. From these causes the 
reconstruction of the charts could not be commenced before 1813, 
which, when the extent of them is considered, will explain why the 
publication did not take place sooner; but it is hoped that the 
advantage in point of accuracy will amply compensate the delay. 
Besides correcting the lunar distances and the variations and 
bearings, there are some other particulars, both in the account of the 
voyage and in the Atlas, where the practice of former navigators has 
not been strictly followed. Latitudes, longitudes, and bearings, so 
important to tbe seaman and ^interesting to the general reader, 
have hitherto been interwoven in the text ; they are here commonly 
separated from it, by which the one will be enabled to find them 
more readily, and the other perceive at a glance what may be 
passed. I heard it declared that a man who published a quarto 
volume without an index ought to be set in the pillory, and being 
unwilling to incur the full rigour of this sentence, a running title 
has been affixed to all the pages ; on one side is expressed the coun- 
try or coast, and on the opposite the particular part where the 
ship is at anchor or which is the immediate subject of examination ; 
this, it is hoped, will answer the main purpose of an index, with- 
out swelling the volumes. Longitude is one of the most essential, 
