212 Dr. Mac CuUoch on the Chart of Shetland. 



the chart does not indicate that the pasage round the Scaw in 

 the former case, or that of Blumel Sound in the latter, are inex- 

 pedient, or even, in certain circumstances, dangerous ; and 

 that it is far preferable to take the southern passage through Yell 

 Sound. The strength of the current through Colgrave Sound, 

 though far less than that of the stream which runs with such 

 velocity through Blumel Sound, renders it also necessary to be 

 well acquainted with the times of ebb and flow through that 

 passage ; no less in merely sailing through it, than in attempt- 

 ing to make the harbour of Basta Voe. As, in leaving a har- 

 bour, every vessel has an opportunity of ascertaining the state 

 of the tide, it is unnecessary to point out the peculiar situations 

 in any of these islands, in which it is necessary to possess this 

 knowledge for that purpose ; but I may remark, generally, that 

 with respect to the making a great proportion of them, a vessel 

 may often fail in its object unless that circumstance is previously 

 well known, and thus be compelled to stand out to sea again. 



In passing round the Skaw, or Papel-ness in Yell or Fedaland 

 Point in North Maven, it is equally necessary to be accurately 

 acquainted with the times of change ; as the strength of the cur- 

 rent is considerable in all these situations, and it is requisite to 

 take advantage of the ebb and flood both, for doubling these 

 headlands ; but on this subject the chart gives no information. 

 The whole of the flood or ebb is equally required for making the 

 passage from Fedaland to Hillswick, or through Swarbuck's 

 Min ; or from Papa Stour to the southern harbours of iEthsting, 

 or the reverse ; and, in all these cases, a miscalculation of the 

 time or velocity of the current, if there is a short wind or a head 

 sea, or both, may be productive of the most serious inconve- 

 niences. The same remarks might be extended to all the re- 

 mainder of the western shore ; but it is unnecessary to enter 

 into minute details of cases which have occurred in my own 

 experience, and which must occur to all vessels attempting this 

 navigation without a well-informed pilot. 



To a stranger, attempting to make any harbour, it is essen- 

 tially necessary to have some physical marks, or picturesque 

 appearances, if that term may be used, by which the spot can 



