x i v INTRODUCTION. 



fathoms. The depths indicate considerable variation over the bottom, and 

 in some regions these changes in depth are very abrupt, from eight to over 

 twenty fathoms in short distances. The character of the bottom varies 

 greatly according to the locality and its vicinity to gaps, to passes, to islands 

 or islets or sand-bars. In many cases the bottom is hard, swept clean by 

 the currents, or covered with fragments coated with Nullipores, or it is cov- 

 ered with Corallines or made up of fragments of broken corals, or of coarse 

 or fine coral sand. On one occasion the claspers brought up a piece of Mil- 

 lepore cut off from a living cluster from a depth of thirty-nine fathoms. 

 This is an unusual depth for a reef builder, as in the Maldives the reef corals 

 rarely extend below seventeen fathoms ; twelve fathoms is the usual depth I 

 have observed, there usually begin the sand lanes and patches which sepa- 

 rate them, and finally end in covering the bottom. 



We did not attempt to check any of the soundings on the Admiralty 

 Charts. Within the atolls they exist in sufficient number for all theoretical 

 and practical purposes, and for a party not sufficiently numerous and not 

 properly equipped for the most delicate surveying operations it would have 

 been hopeless to add any exact information to that already existing. 



Our explorations were immensely facilitated from the existence of the 

 admirable charts published by the Admiralty of the Survey of the Maldives 

 by Commander Moresby and Lieutenant Powell from 1834 to 1836. The 

 accuracy of these charts is something wonderful when we remember the 

 conditions under which the surveys were made nearly seventy years ago, 

 with sailing vessels and rowboats. In our extensive and intricate navigation 

 among the Maldives we were guided absolutely by these charts and never 

 found them in error. Of course some minor changes have occurred on the 

 reef flats, such as the disappearance of an islet or of a bank, or the addition 

 of a sand-bar and the junction of adjoining islands or islets on the same 

 reef flats. Otherwise the charts stand to-day as they did seventy years ago, 

 a monument to the unsurpassed skill of the surveyors of those days. It 

 was a simple task to pick out one's work in each atoll by an examination of 

 the chart, and thus much time was saved. I have endeavored to adopt the 

 spelling of the Admiralty Charts revised to May, 1903, but undoubtedly a few 

 discrepancies will have occurred from our constant use of the older editions. 



