NAVIGATION. 113 



less frequent soundings. An admirable method 

 of navigation by the lead was recently explained 

 to me by Sir James Anderson, who told me he 

 was constantly in the habit of using it in his 

 transatlantic voyages, and that he found it had 

 been independently used by Captain Moriarty, 

 R.N. It seems not to be described in any of 

 the books on navigation, but it is so simple and 

 effective that I think you will be interested if I 

 explain it to you. Take a long slip of card, or 

 of stiff paper, and mark along one edge of it 

 points at successive distances from one another, 

 equal, according to the scale of your chart, to 

 the actual distance estimated as having been run 

 by the ship in the intervals between successive 

 soundings. If the ship has run a straight course, 

 the edge of the card must oe straight, but if 

 there has been any change of direction in the 

 course, the card must be cut with a corresponding 

 deviation from one straight direction. Beside 

 each of the points thus marked on the edge, 

 write on the card the depth and character of 

 bottom found by the lead. Then place the card 

 VOL. III. I 



