The nosepiece, ll|-" over-all length, fabricated of l6-gauge 

 monel, fits snugly over the fore-end of the cylindero It is 

 secured for towing by three monel machine screws (see fig, 3)# The 

 1«6" intake opening permits flow of a water column two square inches 

 in cross section. A reducer with an intake opening of Icl inches 

 (one square inch, X-section) is easily attached to the nosepiece by 

 a set-screw, should this reduction in water flow be considered 

 necessary* 



The cylindrical plankton net is composed of two l6-gauge monel 

 collars, 3" in length and 3" in diameter, connected by three monel 

 rods of 3/16" diameter to form a "frame" for the monel wire-cloth 

 screen* When the sampler is assembled, the net is kept in place by 

 these rods and by the flange on the fore-collar* On the rear collar 

 are two studs for securing the plankton bucket* Woven of wire 

 0*0075" in diameter and $0 meshes to the inch, the wire-cloth has a 

 mesh opening of 0*015 inches* This corresponds approximately to 

 the No* 1 mesh of silk nets and gives a straining (filtering) area 

 of about 280 square inches* Fitting closely over the rear collar 

 of the net, the plankton bucket is secured by a set screw and the 

 studs already mentioned* Two wire-cloth "windows" of the same mesh 

 as the net allow further straining and permit the plankton to 

 settle into the bucket* 



The amount of water that passes through the sampler can be 

 calculated from the number of revolutions registered on the dials 

 of the Atlas current meter. As all water passing through the 

 sampler passes through this meter, reasonable accuracy can be 

 expected* The Atlas meter was selected because of its nickel«plated 

 brass construction, its durability, its easy-to-read dials that can 

 be readily zeroed, and because no modifications were necessary in 

 order to incorporate it as part of the sampler. 



A decided advantage of the Model Gulf I-A sampler is its ease 

 of assembly and disassembly* Once the current meter has been properly 

 installed, it should not have to be removed for the duration of a 

 cruise* Therefore, standard procedure for assembling the sampler on 

 station would be to (1) attach plankton bucket to rear collar of net, 

 (2) insert assembled net and bucket into cylinder, and (3) slide on 

 and secure nosepiece* The l5-pound depressor, secured to an 8-foot 

 length of 3/8" raanila line, is shackled into the bottom towing 

 plate* The ^" stainless steel towing cable is shackled into the top 

 towing plate* Experimental towing showed that the sair^jler towed 

 best with the towing cable and the depressor line shackled into 

 the second hole of their respective towing plates* The dials of 

 the current meter are zeroed just prior to launching the sampler. 

 The current meter, rigged for launching, is illustrated in figure h» 



