THE MUSEUM. 



41 



The Summer Cruise of the Alba- 

 tross. 



Among the interesting features of the 

 stories which all explorers of the bottom 

 of the sea have to tell, are the references 

 made at frequent intervals to the acci- 

 dents happening to the implements 

 used in measuring the depth, bringing 

 up parts of the bottom, recording the 

 temperatures in the depths and gather- 

 ing specimens of the fauna and flora 

 to be found in this unseen land. 

 And in connection with these ac- 

 cidents will be found descriptions of 

 the various machines and appliances 

 used that are only less interesting than 

 the stories of the haps and mishaps of 

 the voyagers. 



When the first attempts at explora- 

 tion were made, a little over forty 

 years ago, the explorers found them- 

 selves, for a time, entirely unable to 

 accomplish even the task of measuring 

 the depth of the water. "The diffi- 

 culty lies in the friction upon the sound- 

 ing line, which prevents the lead going 

 to the bottom where the depth is 

 great," said Prof. W. P. Trowbridge 

 in 1859. It was found, he says, that 

 a 32-pound connon ball, dropping free- 

 ly through the water, fell sixteen feet 

 per second. But when the ball had 

 to drag down a sounding line, even the 

 smallest one that could be trusted to 

 sustain the weight of the ball in the 

 air, the velocity of descent decreased 

 to eight feet per second before 100 

 fathoms of the line had run out, while 

 at 500 fathoms the speed was but four 

 feet per secona. Eventually it was 

 found by actual trial that, although it 

 was a day's work to reach the bottom 

 and haul in the line again, the depth 

 could be measured with sufficient ac- 

 curacy in water where no current was 



encountered. But wherever a current, 

 either at or below the surface, existed, 

 the depth could not be more than 

 guessed, after allowing for the bend in 

 the line caused by the current. 



To overcome the difficulty caused by 

 the friction of the water on the line, it 

 was proposed by one authority to coil 

 the line in a hollow in the sinker, leav- 

 ing one end secured on the exploring 

 ship. To measure the depth, a pro- 

 peller wheel register, on the principle 

 of the speed measurers now used on 

 ships, was to be secured to the sinker 

 and detached and hauled up by the 

 line. This machine did not work in 

 practice. It was proposed also to use 

 insulated wires so arranged that when 

 the sinker rtached the bottom a cir- 

 cuit would be closed and the fact an- 

 nounced on board ship; but this, too, 

 failed, for two reasons, if no more. 

 One important one was that an insul- 

 ated wire would suffer more from fric- 

 tion in going down and from the effect 

 of cross currents than the old-fashioned 

 lines. Eventually a machine was 

 made which was to record the pressure 

 that had been exerted on it when sunk 

 in the water. If this could be accur- 

 ately done, the depth of water reached 

 would be recorded as well, because 

 the pressure increases regularly with 

 the depth. Distilled water was used 

 in the apparatus as the material to be 

 compressed, but experiments showed 

 that the amount of compression varied 

 at different tests at a known depth, 

 from .000,882 per 100 fathoms of 

 depth up to .000,915, and that was 

 too great a variation for accurate 

 measurements. 



Last of all, the makers of pianos 

 came to the aid of the deep-sea explor- 

 ers, and then the problem of measure- 



