turning now to fig1 there may be seen generally at 10 a first preferred embodiment of a reciprocating wind engine in accordance with the present invention . as may be seen in fig1 engine 10 is a generally rectangular housing having a wind or air scoop 12 which supplies additional air to the interior of engine 10 . it will be assumed that the wind is coming from left to right , as indicated by arrow a in fig1 . reciprocating wind engine 10 is further provided with a wind flow control assembly , generally at 14 , whose structure and operation will be discussed in greater detail hereinafter . it will be understood that the representation of reciprocating wind engine 10 in fig1 is schematic and that while the rectangular shape is preferred , the engine could have various other shapes as desired . it will also be understood that plural engines could be placed side by side with their crankshafts joined to each other . further , means could be provided either for mounting an engine on a rotatable platform to facilitate movement in response to wind direction changes or for utilizing selectively positioned engines depending on the wind direction . it will also be understood that the wind engine is intended for use in a number of applications . for example , a bank of engines could be placed on the top of a tall building with their output connected to a shaft of an electric generator . or an engine could be used to operate a pump to pump water into an irrigation ditch . wherever the wind blows and power is required , the reciprocating wind engine in accordance with the present invention could find use . turning now to fig2 there may be seen a top view of the wind engine 10 with the scoop 12 and the top of the device removed . it will be understood that fig2 is also a somewhat schematic view and shows only the general structure of the engine 10 . analogyzing wind engine 10 to an internal combustion engine , wind engine 10 includes a pair of spaced elongated cylinders 20 and 22 , respectively . cylinder 20 will be designated as the windward cylinder and cylinder 22 as the leeward cylinder . each cylinder carries a movable piston assembly 24 and 26 in windward and leeward cylinders 20 and 22 , respectively . each of these piston assemblies is connected to a first end of connecting rods 28 and 30 with these connecting rods being connected , at their second ends , to journals 32 and 34 , respectively of a central crankshaft 36 which is suitably supported by spaced bearings 38 . each piston 24 and 26 has a face comprised of a plurality of pivotable panels 40 which are caused to rotate through 90 ° by a suitable means which will be discussed hereinafter . in operation , wind passes through open panels 42 in the wind flow control assembly 14 , whose operation will also be discussed hereinafter . this wind will contact panels 40 on the face of windward piston 24 and will cause piston 24 to move to the right , as seen in fig2 . movement of piston 24 to the right causes the crankshaft 36 to rotate and to draw leeward piston 26 to the left . the panels on leeward piston 26 are open to minimize wind resistance . as the two pistons reach the inner end of their travel in cylinders 20 and 22 , the panels on pistons 24 and 26 switch orientation . the panels on windward piston 24 open and those on leeward piston 26 close so that the wind force which has pushed the windward piston inwardly now passes through the windward piston &# 39 ; s now open panels and contacts the now closed panels on leeward piston 26 . leeward piston 26 is thus forced outwardly or to the right and windward piston returns to the left . additional wind is supplied through scoop 12 which is in communication with leeward cylinder 22 . as the pistons reach their outer limits of travel , the position of the panels again changes and the next cycle starts . turning now to fig3 there is shown a top plan view , partly in section and showing the wind flow control assembly 14 and the windward piston assembly 24 . referring first to the wind flow control assembly 14 , there are provided a plurality of pivotable panels 42 whose purpose is to direct and control the wind entering the wind engine 10 and contacting , initially , the panels 40 of windward piston 24 . each of the panels 42 is carried on a vertical shaft 44 which is suitably supported by bearings or the like ( not shown ) in upper and lower horizontal frame members 46 . each shaft 44 carries a gear 48 which engages a toothed portion of a rack gear 50 . rack gear 50 is slidably supported by spaced supports 52 that are secured in any desired manner to the upper horizontal frame member 46 . a regulating wind vane 54 is carried on a central hub 55 which , in turn , is secured to a rotatable shaft 56 that also carries a suitable gear ( not shown ) which meshes with rack gear 50 . a control arm 58 extends from hub 55 in a direction generally perpendicular to frame member 46 . control arm 58 is prevented from moving in one direction by a suitable stop 60 , which is secured to the frame of engine 10 . movement of control arm 58 in a second direction is resisted by a coil spring 62 which abuts arm 58 on one end with its second end being secured in a suitable seat 64 carried by upper horizontal frame member 46 . in the operation of control assembly 14 , the wind vane 54 will be struck by the wind which blows generally as indicated by arrow a in fig1 . as may be seen in fig3 the force of the wind will tend to force vane 54 in a counterclockwise direction about shaft 56 . this motion is counteracted by the strength of spring 62 . as vane 54 moves , shaft 56 is rotated and causes rack gear 50 to slide thus changing the direction of panels 42 . if the force of the wind becomes excessive , panels 42 will be forced closed thereby shutting off the wind flow to the engine . it will be seen that this arrangement thereby operates to regulate the wind flow to the engine and to maintain it as constant as possible . as the wind speed increases , the panels start to close with the net result being a constant wind force to the pistons . turning again to fig3 and to fig4 windward piston assembly 24 , which is exemplary also of leeward piston assembly 26 , is comprised of a plurality of lightweight panels 40 which form the face of the piston . each panel 40 is secured to a vertical shaft 70 which is carried in upper and lower frame members 72 and 74 , respectively , as seen in fig4 . it will be understood that shafts 70 are carried by suitable bearings such as shown at 76 and that panels 40 are fabricated to be lightweight while retaining sufficient strength to avoid being bent or twisted by the wind force . side frame members 78 and 80 connect with upper and lower frame members 72 and 74 to form a generally rectangular support frame for the piston face panels 40 . the frame is , in turn , supported in upper and lower tracks 82 and 84 , which are secured to side members 86 and 88 of the engine 10 , by wheels 90 . each of the wheels 90 is supported on a stub axle 92 which extends outwardly from the side frames 78 and 80 . each piston assembly is thus supported for reciprocatory motion by its wheels 90 running in tracks 84 . as may be seen in fig4 suitable adjusting means 94 may be provided to adjust the position of one or more of the wheel tracks . this adjusting means may include a channel member 96 to which the track 84 is secured and which is , in turn , secured to side member 86 by bolts 98 that pass through elongated slots ( not shown ) in channel member 96 . an adjusting bolt 100 may be threaded through a supporting tab 102 to contact channel member 96 . by tightening or loosening bolt 100 , the spacing of track 84 with respect to track 82 can be varied to insure that the tracks are properly spaced . returning to fig3 there may be seen a shifting assembly generally at 110 for causing the piston face panels 40 to open or close . opposed shifting rods 112 and 114 extend rearwardly and forwardly from a slidable shifting shoe 116 which is formed with a diagonal slot 118 . shifting shoe 116 is slidably carried in an upper longitudinal frame chamber 120 that defines the limits of motion of shoe 116 . the piston panels 40 are , as discussed previously , supported on shafts 70 which have gears 122 secured thereto . these gears mesh with a slideable rack gear 124 in a manner similar to the rack gear 50 used in the wind flow control assembly 14 . the free end of rack gear 124 extends beyond upper frame member 72 and terminates in a pin 126 which is located in slot 118 of shifting shoe 116 . fig3 and 5 show the windward piston assembly at the ends of its stroke and show the operation of the shifting assembly 110 to vary the position of panels 40 . in fig3 the front shift rod 114 is in contact with a front shift stop 126 to force shifting shoe 116 to the rear thereby pulling rack gear 124 to the right to close the piston panels 40 . in fig5 it will be seen that the windward piston assembly 24 has traveled to the rear of its stroke where rear shift rod 112 contacts a rear shift stop 128 to force shift shoe 116 forward thus moving rack gear 124 to the left to open the piston panels 40 for the return cycle . the operation of the leeward piston is essentially the same with the exception that the shift shoe &# 39 ; s slot is reversed so that the piston panels close at their inner limit of travel of the piston assembly and open at the outer limit of piston travel , as is shown in fig2 . summarizing the operation of this first preferred embodiment of a reciprocating wind engine , the wind is allowed to flow through panels 42 of the wind flow control assembly 14 . the wind flow to the windward piston is maintained constant by the movement of wind vane 54 which controls the opening of the panels 42 . the wind then strikes the closed panels 40 of the windward piston assembly 24 to drive this piston to the right , as seen in fig2 . piston assembly 24 is supported by wheels 90 riding in upper and lower tracks 82 and 84 . the motion of piston assembly 24 is communicated to crankshaft 36 by a connecting rod 28 which is suitably secured to windward piston assembly 24 . as this piston assembly moves to the right , the leeward piston assembly 26 , whose panels have been opened by shifting assembly 110 , is pulled to the left by its connecting rod 30 which is also secured to crankshaft 36 . when the two pistons are closest to each other , their respective shifting assemblies open the panels on windward piston assembly 24 and close the panels on leeward piston assembly 26 . the wind force now passes through piston 24 , hits piston 26 , is augmented by wind coming in through scoop 12 , and forces the pistons apart thereby continuing the rotation of crankshaft 36 whose output can be used in any desired manner . a second preferred embodiment of a reciprocating wind engine in accordance with the present invention is shown generally at 130 in fig6 and 7 . as may be seen in fig6 a plurality of piston assemblies 132 are placed side by side , which is in contrast to the first embodiment which showed opposed pistons . each piston is otherwise the same as the pistons discussed previously in terms of its mounting and operation . each piston has a connecting rod 134 with the outer two pistons , as seen in fig6 being connected to flywheels 136 and the inner pistons being connected to journals 138 of crankshaft 140 which is also joined to flywheels 136 . crankshaft 140 carries a pulley wheel 142 which is joined to a conventional generator 144 by suitable belts 146 . a wind flow control assembly 148 is carried in front of the pistons 132 and is the same in structure and function as the corresponding assembly 14 discussed in connection with the first preferred embodiment . in fig7 there may be seen a schematic rule elevation view of the second preferred embodiment of a reciprocating wind engine with portions removed for clarity . this assembly is mounted on a platform 150 which can move on a base 152 to reposition itself as the wind changes . a wind vane 154 is carried by reciprocating wind engine 130 and acts to maintain the engine headed into the wind . as the wind direction changes , the engine 130 will be rotated on its base 152 so that it maintains the wind flow control portion 148 of the engine pointed into the wind . the schematic view of fig7 shows two pistons . it will be understood that this a schematic view and that the necessary supporting wheel tracks , frame structures , and the like have been omitted for convenience since fig6 and 7 are intended only to show the concept of operation of this reciprocating wind engine 130 and not the structural specifics which are the same as those previously described in connection with the first preferred embodiment . this embodiment would be particularly useful in an application where the wind direction was variable or where space limitations preclude the placement of several motors in different directions . while there have hereinabove been fully and completely disclosed first and second preferred embodiments of a reciprocating wind engine in accordance with the present invention , it will be obvious to one of skill in the art that a number of changes could be made . for example the shape of the pistons and panels , the types of materials used , the number of wheels which carry each piston assembly , the shape of the wind control vane , the structure of the crankshaft and connecting rods , the arrangement of bearings , and the like are changes which could be made without departing from the true spirit and scope of the reciprocating wind engine in accordance with the present invention and accordingly , the invention is to be limited only by the appended claims .