22 A TEDIOUS BRIEF EXPLANATION 



what, for want of a better phrase, I must call the 

 purely scientific work of the ship, in which the natur- 

 alist is one of the chief participators. This with us 

 consisted exclusively of deep-sea sounding, deep-sea 

 thermometry, and trawling and dredging. 



For deep-sea sounding the old, slow, clumsy, and 

 doubtful rope-line has long been discarded, and all 

 survey-ships now use some sort of sounding-machine 

 like that which I shall now attempt, not to describe, 

 but to convey a general idea of. 



The sounding apparatus used by the Investigator 

 in my time, consisted of a Sir William Thomson 

 sounding-machine and a Baillie sounding-rod. With 

 this we used, instead of a rope, a fme line of steel wire 

 like a piano string. The advantages of this over rope 

 are — that it offers no surface for friction, and can there- 

 fore be paid out and hauled in quickly ; that it is 

 not buoyant, and therefore is not liable to drift away 

 among under-currents ; that it does not increase in 

 weight by getting water-logged ; and lastly, but most 

 potently, that it is compact and manageable, since 4000 

 or 5000 fathoms of it can be reeled on a light drum 

 only 2 feet in diameter. 



When in use, the drum on which the sounding- 

 wire is reeled revolves on a common axle with the 

 driving-wheel of a steam-engine of almost toy propor- 

 tions, and by this means the wire, after having been 

 eased out to make a sounding, is reeled in again when 



