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HYDROGRAPHY. 



[Sect. III. 



height of the lantern 



the tower, whether the light he fixed or revolving, inter- 

 mittent, coloured, or otherwise ; the distance which it 

 may be seen, and the bearings on which the light is 

 visible. If the light be made use of for the purpose of 

 avoiding any danger, state what the danger is, give its 



bearing from the lighthouse, and if the light be blinked or 



changed for this or any other purpose, state what it is, and 

 give the exact bearing on which the change takes place. 



If there be a lower light in the tower for this, or any 

 purpose of tide work, state as before the bearing on 

 which it opens and obscures, or the times of tide when it 

 is exhibited and extinguished, and how many feet it is 

 below the upper light. State wliether pilots are required 

 for the port, and where they are likely to be met with, 



of 



In Port. 



15. \Vhen at anchor, give the depth of the water, nature 



of the orround, an 



d whether any precautions are neces- 



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sary, with respect to protecting the cables if hempen, and 

 whether it be proper to moor in consequence of the diffi- 

 culty of keeping a clear anchor, or from the treacherous 

 holding or sloping of the ground. Fix the spot by cross- 

 bearings of conspicuous and well-known objects, and note 

 the direction and rate of the tide, and the duration of 

 both ebb and fxood stream. 



16. The geographical position of a port will necessarily 



3Upy the attention of thft nprsntiQ in wh<,«fi hands 



of the persons in whose hand 

 remarks may be placed, and by assiduity much 

 may be done in a short time with a sextant and artificial 



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