ii4 POPULAR LECTURES AND ADDRESSES. 



on the chart, and slip it about till you find an 

 agreement between the soundings marked on the 

 chart and the series marked on your card. The 

 slight ups and downs of the bottom, even if they 

 be no more than to produce differences of five or 

 six fathoms in depths of, say, from five-and-thirty 

 to fifty fathoms, interpreted with aid from the 

 character of the bottom brought up, give, when 

 this method is practised with sufficient assiduity, 

 an admirably satisfactory certainty as to the 

 course over which the ship has passed. Sir James 

 Anderson tells me that he has run from the 

 Banks of Newfoundland for two days through 

 a thick fog at twelve knots, never reducing speed 

 for soundings, but sounding every hour by the 

 deep sea lead and Massey fly, has brought up 

 his last sounding black mud opposite to the mouth 

 of Halifax Harbour, and has gone in without 

 ever once having got a sight of sun or stars all 

 the way from England, or of headland before 

 turning to go into harbour. 



[Addition of August 4th, 1887. The taking 

 of soundings with the ordinary deep sea rope 



