14 bulletin: museum of compaeative zoology. 



were synchronous, they must have produced considerable warping of the 

 surfaces enclosed within the area explored by the " Wild Duck." 



Mr. William H. Tillinghast has published some " Notes " l on the 

 historical hydrography of the Handkerchief Shoal,- " thinking that an 

 examination of old maps might reveal a change of condition in the shoals 

 since the time of the discovery of the Bahamas. . . . They throw more 

 light on the condition of the cartography of the West Indies than on 

 any physical changes among the islands." 



An examination of the earliest charts of the Mouchoir Bank enu- 

 merated in the " Notes " which Mr. Tillinghast was kind enough to make 

 with me at once showed the impossibilit}^ of their having been based upon 

 actual surveys. On the chart of Thomas Jeffreys (1775), the Windward 

 Passage from the east end of Cuba and the north part of Saint Domingo 

 there is a legend regarding the Banc du Mouchoir Quarre : " This bank 

 is very little known. The soundings are taken from an English chart." 

 It contains nine islands. On writing to Captain W. J. Wharton, E. N., 

 Hydrographer of the Admiralty, regaining this English chart, I was 

 kindly informed by Staff Commander Tizard that there appeared to 

 be no earlier chart at the Hydrographic Office than that of 1775 by 

 Thomas Jeffreys. 



It is most natural that in those days, when computations for longitude 

 wei'e comparatively inaccurate, that in a region where the currents are 

 most variable and often quite strong, the positions assigned to shoals and 

 islands should be very inaccurate. 



Even at the present time it is most difficult, owing to the varying 

 strength of the currents, to pick up the position of well known banks, 

 and still more difficult to find banks like that on which the " Superb " 

 and " Severn " anchored, the position of which never was accurately 

 fixed. But little importance can be attached to islands as. shown on an 

 old chart. On banks like those to the eastward of Turk's Islands (Mou- 

 choir and Silver Banks), where there are many rocks awash, it is not 

 impossible that patches of rocks awash should have been mistaken for 

 islands by ordinary observers, and so marked on the charts. 



But when we come to actual surveys, such as those of Count de Chas- 

 tenet-Puysegur (1787), who cruised over the Silver Bank and Mouchoir 

 Quarre and took a number of soundings, we get a fairly accurate account 

 of the aspect of the shifting bottom, of the rocks awash, and a series of 

 quite characteristic soundings, but no islands are reported or plotted on 

 the shoals. 



1 Library of Harvard University, Bibliographical Contributions, No. 14, 1881. 



