in the present advanced state of navigation, that they should not have been before discovered and a mode of preventing or correcting 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 conformable 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 voyage 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 the seaman and uninteresting 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 country 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, without swelling the volumes. Longitude is one of the most essential,
