as shown in fig1 and 2 , the game call of the present invention is a whistle which is generally comprised of a mouthpiece 2 , venting means 4 , a constant volume air chamber 6 covered by a cap 8 , and a variable volume air chamber 10 containing a barrel 12 which holds a piston arm 14 . the mouthpiece 2 and air chambers 6 and 10 are formed by the cooperation of upper portion u ( fig3 ) and lower portion l ( fig4 ). both portions u and l are provided with channels 16 and 18 which , placed in a top and bottom relationship form the constant volume 6 and variable volume 10 air chambers , respectively . so formed , the air chamber 6 and 10 are separated by a common wall 20 which is formed by the cooperation of the upper and lower parts of the common wall 20 contained in the upper and lower portions and extends partially into mouthpiece 2 to separate the mouthpiece 2 into two separate passageways . this upper and lower portion construction of the present invention resulting in forming adjacent air chambers separated by a common wall , rather than two distinct and separate air chambers in a side by side relationship , creates a game call which more accurately imitates the desired bird sounds and which is substantially simpler to manufacture with greater precision than was attainable by any of the prior art devices . to provide a game call with the desired tone ranges it is desirable to construct the game call with one chamber that is of a constant volume and a second chamber which is provided with a volume varying means which thereby varies the created tones . therefore , in the present invention constant volume air chamber 6 , formed by the upper and lower channel 16 , is provided with a cap 8 which is constructed at a size which will create a chamber 6 of the precise volume desired . to create a variable volume chamber , chamber 10 , formed by the upper and lower channels 18 , is provided with a hollow barrel 12 which holds piston arm 14 which by sliding within barrel 12 varies the volume of chamber 10 . in order to insure that variable chamber 10 will have the proper minimum and maximum volumes , lower channel 18 is provided with a lip 22 which prevents the further inward positioning of barrel 12 , and barrel 12 is provided with a collar 24 which by abutting outer edges 26 of variable chamber 10 additionally prevents further inward positioning of barrel 12 . after barrel 12 is properly positioned in variable chamber 10 , piston arm 14 is placed in barrel 12 with grooved bottom plate 28 at the lower end of barrel 12 , ring 30 abutting upper edge 32 of barrel 12 , and plunger arm 14 projecting outward terminating with cap 34 . to maintain the proper range of positioning for piston arm 14 , there is provided thereon a flange 36 which by abutting with the extended edge 38 of ring 30 prevents undesirable upward motion of the piston arm 14 and which by abutting with the inside of barrel 12 prevents undesirable wobble of the piston arm 14 . additionally , the cap 34 and piston arm 14 are manufactured at a proper size to prevent undesirable downward motion of the plunger arm 14 by the abutting of cap 34 with ring 30 . the piston arm 14 is further provided at its grooved bottom plate 28 with a sealing means , such as o - ring 39 , for preventing escape of air out of the variable air chamber 10 through the space between ring 30 and piston arm 14 . for insuring sufficient strength and durability , plunger arm 14 is most advantageously manufactured in the shape of two intersecting planes which fit between the pins 40 in cap 34 for preventing undesired rotational movement of arm 14 within cap 34 . however , it is obvious that any shaped plunger arm and cap of sufficient strength and durability are suitable for the purposes of the present invention . the game call of the present invention may additionally be provided with an attaching means 42 for accepting a cord or the like for securing the call to a person or object . furthermore , upper portion u is provided with projections 44 which cooperate with depressions 46 in lower portion l and thereby aid in the proper alignment of the two portions during manufacture of the game call of the present invention . in its use , the tones produced by the game call of the present invention may be varied by changing the volume of chamber 10 with piston arm 14 and / or by alternately restricting the air flow through vents 4 . because the sounds produced are dependent upon the volumes of the air chambers without the need of a reed or the like , the game call of the present invention can be made of a lightweight plastic and continuously accurately reproduce the calls of game birds without being undesirably affected by wear and weather conditions . while this invention has been described as having a preferred design , it will be understood that is is capable of further modification . this application , is , therefore , intended to cover any variations , uses , or adaptations of the invention following the general principles thereof and including such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains , and as may be applied to the essential features hereinbefore set forth and fall within the scope of this invention or the limits of the claims .
a game call or the like whistle which includes a housing member with a mouthpiece and two air chambers with one of the air chambers having a constant volume and the other air chamber having a variable volume containing therein a piston arm for changing the volume of the variable chamber . the game call is formed by the cooperation of a top portion and a bottom portion which when placed together form the two air chambers and mouthpiece with a common wall separating the two chambers .