1916] 31icJiaeI, et al.: fTijdrogmphic Records of Scripps Institution 209 



A. COLLECTING APPARATUS AND EXAMINATION 

 OF DATA FOR ERRORS 



1. NEW APPARATUS 



a. Serial closing apparatus. — The first step toward more intensive 

 and continuous investigations consisted in devising an apparatus com- 

 bining the essential advantages of the Kofoid closing net (Kofoid, 

 1911) and El<man reversing water bottle (Ekman, 1905). Thanks to 

 the mechanical ingenuity of our engineer, Jlr. James Ross, two such 

 pieces of apparatus have been constructed (text-figs. A, B, and C). 

 Tliey are not only adapted to simultaneous operation on the same 

 cable, but have the additional advantage that two "equivalent" hori- 

 zontal closing nets form an essential part of each. The two nets lie 

 about six inches apart on opposite sides of the cable (text-figs. B and 

 C), and, since they are operated simultaneously, duplicate hauls are 

 made at each depth — one net thus acting as a check against the other. 

 In connection with each pair of nets, a rack (t.r.) for holding two 

 reversing thermometers and a small bottle (w.b.) for securing water 

 samples are provided, which are operated upon closure of the nets. 

 Each .serial closing apparatus, therefore, con.sists essentially of two 

 "equivalent" closing nets, a thermometer rack, and a water-sample 

 bottle. The two already constructed weigh approximately fifty pounds 

 apiece, but it is proposed that the next ones shall be made materially 

 lighter. This can be accomplished by pressing out the metal parts 

 instead of casting and machining them. 



After each apparatus is clamped onto the cable and lowered to the 

 desired depth, a messenger is dropped which opens the first pair of 

 nets and releases a .similar messenger which opens the second pair, etc. 

 After the desired length of time, another mes.senger is dropped which 

 closes the first pair of nets, reverses the thermometers, secures the 

 water sample, and releases a similar messenger which operates the 

 second apparatus in the same way, and so on for the whole series. 



Important advantages of this apparatus are : 



1. Duplicate closing-net hauls and corresponding temperatures and 

 water samples obtained simultaueou.sly at each of a series of depths. 



2. Reversal of the thermometer rack closes the water bottle, which 

 makes it mechanically impossible for the thermometer to register at 



