Plankton sample taking apparatus
RELATED APPLICATION 
     This application is a division of application Ser. No. 520,567, filed Aug. 5, 1983, now U.S. Pat. No. 4,558,534. 
    
    
     BACKGROUND OF THE INVENTION 
     In the taking of plankton samples from a body of water it is conventional to secure the smaller end of a conical net to the open end of a sample container and move the assembled net and container through the body of water. Apparatus of this kind is disclosed in Phillips Pat. No. 4,089,131. Although the apparatus disclosed in that patent is satisfactory, extensive use of such apparatus has revealed the desirability of improvements. For example, the patented apparatus uses a container having a relatively small neck. The passage of samples into and out of the container and cleaning of the latter are easier if the relatively small neck container is replaced by a wide-mouth container. 
     Although the apparatus disclosed in the Phillips patent is capable of effecting an excellent seal between the container and the coupling by means of which the container is coupled to the plankton net, it is possible for plankton to become wedged between the external surface of the container neck and the innermost part of the coupling. This possibility is increased in the event that the container and coupling are carelessly assembled or in the event that towing of the apparatus through a body of water causes relative rotation with consequent looseness between the container and the coupling. This problem can be solved by the provision of a sealing bead on the coupling which is accommodated in the mouth of the container and by providing a latch for preventing unintentional relative rotation between the container and the coupling. 
     SUMMARY OF THE INVENTION 
     Sample taking apparatus constructed in accordance with a preferred embodiment of the invention comprises a container closed at one end and terminating at its other end in a wide-mouth opening having a tapered lip. The container is coupled to the smaller diameter end of a conical gathering net by means of an assembly of telescoping members, one inner member of which is accommodated within the net and receives the mouth end of the container. This coupling member has a shoulder on which the lip of the container mouth may seat, and such shoulder is provided with an annular bead which projects into the mouth of the container. The bead and the lip are complementally tapered so as to provide a wedging seal between the container and the coupling member. 
     The container has an opening in its side covered with a fine mesh screen which permits water, but not plankton, to flow outwardly from the container. The screen is protected against damage by a plurality of bars carried by the container and overlying the screen. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The presently preferred embodiment of the invention is disclosed in the following description and in the accompanying drawings, wherein: 
     FIG. 1 is a side elevational view of a plankton sampler coupled to one end of a gathering net, the net being shown fragmentarily; 
     FIG. 2 is an exploded view, partly in section and partly in elevation; 
     FIG. 3 is an enlarged, sectional view illustrating the net and the coupling in assembled condition; and 
     FIG. 4 is an enlarged sectional view taken on the line 4--4 of FIG. 1. 
    
    
     DETAILED DESCRIPTION 
     Apparatus constructed in accordance with the disclosed embodiment of the invention is adapted for use in conjunction with any one of a number of different kinds of conical sample gathering nets 1 having a tapering body 2 formed of nylon or other suitable netting material and equipped with axially extending reinforcing strips 3, as is conventional. At its larger diameter end the body 2 has a reinforcing band 4 of suitable material and is provided with openings 5, reinforced by suitable grommets 6, through which a towing bridle 7 passes. The bridle is connected to a ring 8 which may be attached to one end of a tow line. Preferably, a rigid hoop 9 is fitted at the larger diameter end of the body 2 so as to maintain that end of the body open. The smaller diameter end of the body 2 preferably includes a short, cylindrical neck portion or cod 10. 
     The net is adapted to be fitted to a container 11 which, in the disclosed embodiment, comprises a generally cylindrical body 12 open at one end. The body may be closed at its other end and provided with a substantially semicircular opening 13 in one side thereof. Alternatively, the body could have impervious sides and be open at its bottom. In any case, a suitable screen 14 of fine mesh material, such as nylon or stainless steel, overlies the opening 13 (or the bottom opening) and is secured in place by conventional means, such as adhesive or resilient retainers 15 which, together with the marginal edges of the screen 14, are accommodated in grooves 16 that encircle the opening 13. Preferably, the body 12 is provided with reinforcing bands 17 which underlie the screen 14. If the body is formed of a metallic material, the screen may be welded or soldered to the body. 
     In a preferred construction the body 12 is provided with arcuate, axially spaced ribs 18 and 19 that are spanned by protective rods 20 which overlie the screen 14. The rods are secured at their opposite ends by nuts 21. The upper rib 19 has at least one opening 22 therein for a purpose presently to be explained. 
     At the open end of the body 12 is a flange 23 provided with an external thread 24. The body has a mouth 25 from which extends a tapered lip 26 having an inclined, radially inner surface 27 which slopes in a direction toward the open end of the container body. The cross sectional area of the mouth 25 of the body corresponds to the cross sectional area of the body at any point along its length. 
     Apparatus for coupling the net 1 to the container 11 is designated generally by the reference character 28 and comprises an inner, annular body 29 at one end of which is an enlarged flange 30 having a bore 31 formed with a thread 32 which corresponds to the thread 24 on the container body 12. The bore 31 terminates in an internal, radially extending shoulder 33 at the radially inner edge of which is an annular, tapered bead 34 which extends axially of the body 29 and is radially spaced from the bore 31 to form an annular groove. The bead 34 has an inclined, radially outer surface 35 which confronts the surface 27 of the lip 26 and the lip and the bead are so located that the lip is accommodated in the groove between the bead and the skirt and nests with the lip with the surfaces 27 and 35 engaging one another with sufficient force to form an interference sealing fit when the body 29 is screwed onto the container body 12. 
     The coupling body 29 also includes a generally cylindrical section 36 having an outer diameter corresponding substantially to that of the cod 10 of the net 1. The section 36 has a convex, smoothly rounded free end 37, and it also has a cylindrical bore 38 which merges with a tapered bore 39 that diverges in a direction toward the skirt of the body and communicates with the bore 31. The section 36 of the coupling body 29 also has an external, annular groove 40 therein. 
     The coupling apparatus 28 also includes an outer anchor ring 41 having an annular skirt 42 of such diameter as to accommodate the cylindrical section 36 of the coupling body 29. The anchor ring 41 terminates at one end in an annular flange 43 which overlies the end 37 of the coupling body 29 and has an outwardly convex surface 44. The skirt 42 also has an annular groove 45 in its inner surface and at a height to confront the groove 40. A rubbery, deformable retaining ring 46 is adapted to be accommodated in the grooves 40 and 45. 
     To assemble the net 1 with the coupling apparatus 28, the cod 10 is threaded through the ring 41 and through the retaining ring 46. The cylindrical section 36 of the coupling body 29 then is fitted into the cod 10 of the net 1. The retaining ring 46 then may be stretched and moved into encircling relation with the cod 10 and the section 36. When the ring 46 reaches the groove 40 it will contract and wedge the adjacent portion of the cod 10 into the groove 40. Thereafter the anchor ring 41 may be slid longitudinally over the cod 10 and the section 36 until the flange 43 seats upon the free end 37 of the member 29 so as to compress the cod 10 between the surface 37 and the flange 43. 
     Movement of the anchor ring 41 toward its seated position will subject the retaining ring 46 to radially compressive force. The groove 40 has a width greater than the diameter of the ring 46, however, so compression of the ring 46 enables the latter to be deformed into the groove. When the groove 45 reaches the level of the ring 46, the latter will expand radially and occupy the groove 45, thereby providing a secure, but nevertheless releasable, coupling of the members 29 and 41 to one another. In these positions of the parts, that portion of the cod 10 which occupies the groove 40 will be securely retained therein so as to preclude inadvertent separation of the net from the coupling apparatus. 
     Following the assembly of the coupling apparatus and the net 1, the mouth of the container body 12 may be fitted into the threaded bore 31 of the coupling body 29 and the two parts relatively rotated so as to cause the lip 26 to enter the recess between the skirt and the bead 34 and move toward the shoulder 33. As the lip moves toward the shoulder, the lip surface 27 and the bead surface 35 will engage one another with a wedging action resulting in an interference seal between the lip and the bead, thereby precluding any likelihood of the admission of water or plankton radially outwardly of the lip. 
     Following attachment of the coupling body 29 to the container body 12, a latch pin 47 may be extended through the opening 22 in the rib 19 and through a corresponding opening 48 in the flange 30. The latch pin 47 is provided with retaining nuts 49 or the like at its opposite ends. The latch pin 47 positively precludes relative relative rotation between the members 12 and 29, thereby ensuring the preservation of the seal between the lip 26 and the bead 34 and precluding any possibility of loss of the container 11. 
     The securing of the net 1 to the coupling apparatus 28 preferably occurs at the zone at which the cod 10 commences. This will enable the cod to negotiate the substantially right angular bend necessitated by the flange 43, but will not impose any significant stress on the juncture of the net and the cod as the assembled apparatus is drawn through a body of water. 
     To uncouple the net from the coupling apparatus 28, the anchor sleeve 41 may be slid upwardly from the position shown in FIG. 3 toward the position shown in FIG. 2, thereby exposing and permitting access to the ring 46, following which the ring and the cod 10 may be removed from the groove 40 in the coupling member 29. 
     The disclosed embodiment is representative of a presently preferred form of the invention, but is intended to be illustrative rather than definitive thereof. The invention is defined in the claims.