ON DEEP-SEA SOUNDING. 353 



the sounding weight ; so that, although a 

 little of the hemp line may coil on the 

 bottom, the wire may be quite prevented 

 from reaching the bottom. A galvanised 

 iron ring, of about half a pound weight, 

 is attached to the lower end of the wire, 

 so as to form the coupling or junction 

 between the wire and the hemp line, and to 

 keep the wire tight when the lead is on the 

 bottom, and the hemp line is slackened. The 

 art of deep-sea sounding is to put such a 

 resistance on the wheel as shall secure that 

 the moment the weight reaches the bottom 

 the wheel will stop. By " the moment " I 

 mean within one second of time. Lightness 

 of the wheel is necessary for this. The 

 circumference of the wheel is a fathom, with 

 a slight correction for the increased diameter 

 from the quantity of wire on. Whatever 

 length of wire is estimated as necessary to 

 reach the bottom is coiled on the wheel. 

 For a series of deep-sea soundings, in depths 

 exceeding 1,000 fathoms, it is convenient to keep 

 VOL. III. A A 



