THE MUSEUM. 



43 



EXAMINING THE CONTENTS OF A TRAWL. 



STEAMER ALBATROSS SOUNDING. 



strikes the bottom, when the steel tube 

 is jabbed into the mud and the bail of 

 the big ball is thrown out of the hook, 

 a spring that is released as the weight 

 is removed helping to throw out the 

 weight's bail. 



But that is not all. There is a 

 valve in the bottom of the steel pipe 

 that shuts in whatever mud or sedi- 

 ment may be inclosed. There is also 

 a registering thermometer fastened on 

 the sounding wire. It need not be de- 

 scribed in detail, but it is worth say- 

 ing that it has to be inclosed in a glass 

 tube that will resist a pressure of a col- 

 umn of water six miles high — a pres- 

 sure measured by the ton. Moreover, 

 the registering of the temperature is 

 effected by reversing the thermometer. 

 This is done by releasing a catch at 

 the top of it, and this catch is released 

 by a propeller wheel that revolves as 

 soon as the men begin to haul in on 

 the sounding wire. 



Measuring the depth and taking the 

 temperature of the water and bringing 

 up specimens of the mud are, however. 



only a small part of the work of ex- 

 ploring the bottom of the sea. Collec- 

 tions of the plants and animals found 

 there are wanted. \\'hen this work of 

 collection was first begun a weighted 

 bag with a scoop-shaped mouth was 

 towed slowly along on the bottom of 

 the sea at the end of a long rope. It 

 was as if a leather mail pouch were 

 tied at the end of a rope and dragged 

 across the fields in order to 

 collect specimens of the fauna and 

 flora. And after thirty years of 



work nothing better in principle has 

 been invented. They have an im- 

 proved bag and net trawls; they have 

 an improved shape to the scoop, and a 

 flexible steel rope a quarter-inch in di- 

 ameter takes the place of the hemp 

 rope five times as large. But if there 

 be any deep-water whales or any be 

 ings as large as a man haunting the 

 depths the appliances in use are not 

 adapted to capture them. However 

 inefficient as the scoop appears to be, 

 the results attained are marvellous, for 

 more than 100,000 different forms of 



