32 THE LAST CRUISE OF THE CARNEGIE 



nable habit of getting tangled up once the mechanism was safely 

 hidden from view in the waters under the vessel. It was a rare 

 day when three consecutive hauls were successful. Neverthe- 

 less, with its aid we were able to make a census of the sea's popu- 

 lation in various regions and at the various depths — a valuable 

 contribution to our knowledge of life in the ocean. The pump 

 was designed by Dr. Petterssen of Norway, and had been tested 

 off the coast of that country by Dr. Sverdrup, a Research As- 

 sociate of the Carnegie Institution. 



Immediately inboard from the plankton-pump platform is a 

 large "gear-box" filled with oceanographic instruments. Stand- 

 ing on the outside in ranks, like well drilled veterans, are the 

 reversing water-sampling bottles, designed by the late explorer 

 Nansen. These remarkable brass cylinders may be attached in 

 series to the bronze wire, lowered to the desired depths, and 

 reversed by dropping a brass messenger down the cable from the 

 ship. Each bottle has a messenger hanging at its lower end, so 

 that when the first bottle reverses end-over-end, its messenger 

 continues down the wire to upset the next. The two valves at 

 the ends of each bottle close automatically when reversal takes 

 place, imprisoning about a quart of water, to be analyzed by the 

 chemist in the laboratory on deck. To each of these bottles is 

 attached a small frame containing the all-important deep-sea 

 reversing pressure thermometers. 



Inside the gear-box are several types of "bottom-samplers." 

 Some consist of brass tubes surrounded with lead weights which 

 fall off after the apparatus plunges into the ocean-floor. Others 

 operate like a clamshell or turtle's jaws, snapping up a sample of 

 bottom-deposit. A third kind is a long, glass-lined metal tube 

 with a heavy weight permanently attached to it, which procures 

 a vertical section of the mud or ooze, showing the successive layers 

 in which it has been deposited. But the sampler most commonly 

 used is a modification of the telegraph "snapper" of the clam- 

 shell type. Like the plankton-pump, this mechanism required 

 considerable nursing, and even some surgical operations as time 

 went on. 



On the basis of these samples a study of the nature and origin 



