NARRATIVE OF THE CRUISE. 71 



an accident is sure to occur. Where steam power is not available for heaving up, the 

 wire possesses a very great advantage, for it can he easily worked, even at very great 

 depths, by hand. 



Captain Belknap of the U.S.S. "Tuscarora," who in 1874 sounded out the route from San 

 Francisco to Japan, and in so doing surveyed the deepest water in the world, did all 

 his sounding by hand. His successor Captain Sigsbee, the author of the admirable 

 volume on deep-sea sounding and dredging, 1 devised and constructed an elaborate wire- 

 sounding apparatus with steam power, especially adapted for scientific work. More 

 recently, Captain Magnaghi, Hydrographer to the Italian Navy, has fitted his ship the 

 " Washington " throughout with wire, not only for deep-sea work, but for ordinary 

 harbour surveying, all the boats used in this work being fitted with small stages for the 

 wire sounding reel. 



It is evident, then, that in the twelve years which have elapsed since the Challenger 

 cruise began, the use of wire for sounding purposes has received enormous development. 

 For purposes of deep-sea investigation, however, which includes actual sounding only as 

 one of its items, good hemp sounding line is still indispensable. It is of course necessary 

 to have steam power for working the line. With it in depths up to 500 or 600 fathoms 

 hemp is better for all purposes than wire, and is equally expeditious, for a sinker can be 

 used to make it descend- nearly as quickly as wire, and with instruments attached it can 

 be hove in with safety more rapidly from such depths than wire. Deep-sea thermo- 

 meters which have been carefully compared with a standard, and which have been used 

 in many soundings, are instruments of very great value, and if lost, are not replaced by 

 the purchase of new ones. Further, it is important at every station to observe the tem- 

 perature at as many different depths as possible. Where wire, with its liability to break, 

 is used, it is very imprudent to use more than one or two valuable thermometers at a 

 time, while with hemp, which is almost absolutely free from risk of rupture, eight or ten 

 thermometers may be sent down at once. Therefore to obtain, with safety, the same 

 number of observations with the wire, would require the operations of sinking and heaving 

 in to be repeated a greater number of times than with the hemp ; and as a thermometer 

 must be allowed a certain time to take the temperature of the water, it is evident that 

 for such work the wire is in the end not more expeditious than the hemp. 



With regard to dredging, which formed so important a part of the Challenger's work, 

 there can be no doubt of the great superiority of wire over hemp rope. The advantage in 

 point of rapidity of work and of saving in stowage is much greater than in the case of 

 sounding. Here we are indebted for a scientific instrument to the enterprise of those 

 engaged in the manufacture of telegraph cables, for it is owing to the development of 

 this industry that there is now a regular manufacture of the beautifully flexible steel-wire 

 hawsers which are now to be found on board almost every well-appointed ship. 



1 Sigsbee, Deep-Sea Sounding and Dredging, Washington, 1880. 



