referring now to fig1 it will there be seen that an exemplary embodiment of the invention is denoted as a whole by the reference numeral 10 . in a first embodiment , machine 10 includes a first elongate table means or envelope feed conveyor means 12 having a very large plurality of envelopes 14 disposed thereatop . a second elongate table means , denoted 16 as a whole , is disposed in parallel relation to first elongate table means 12 , in transversely spaced apart relation to first elongate table means 12 . as depicted in fig2 a , a plurality of sheet feeders are mounted in longitudinally spaced apart relation to one another . in this particular embodiment , there are five sheet feeders , denoted 18a - e , but a commercial embodiment of the invention includes six of such feeders ( see fig5 ). the number of sheet feeders is not critical to the operation of machine 10 . as in prior art machines , each sheet feeder carries a replenishable stack of individual paper sheets 20a - e to be inserted into envelopes as a set . a flighted conveyor belt 22 carries the paper sheets to the forward end of second table means 16 , as indicated by arrow 23 , where the individual stacks are sequentially inserted into envelopes 14 . in fig2 a , belt 22 is divided into sections or bins by longitudinally - spaced apart vertical walls 24 . this particular configuration is used for sheets having a longitudinal extent in excess of six inches ; walls 24 are 141 / 4 inches apart . a sheet of paper that is to be positioned at the bottom of a stack is deposited into a bin at position 26e by a roller mechanism that is well - known . that sheet then advances to position 26d and the sheet that will be the second from the bottom in the stack is then deposited atop it and so on until the stack has been assembled for insertion into an envelope . in this example , the top sheet in the stack is deposited atop said stack at position 26a by sheet feeder 18a . note that only two sets of pusher members , denoted 28b and 28d , are used in this first embodiment . where the pusher members are carried on an endless chain means or belt means 28 having a length of forty inches , the two sets of pusher members are spaced twenty inches from one another . chain means 28 follows a generally elliptical path of travel so that the pusher members do not abruptly change direction as the chain means rotates in a vertical plane . it should be understood from fig1 that chain means 28 includes two sets of parallel chain members disposed in transversely spaced apart relation to one another , and that the pusher members are disposed therebetween . the configuration of fig2 a is employed when the sheets to be inserted are greater than six inches in length . in the configuration of fig2 b , walls 24 are spaced 71 / 8 apart , and three pusher members , denoted 28a , 28c and 28d are employed . on a forty inch chain means , they are equidistantly spaced from one another at 13 . 33 inch intervals . this configuration is used when the sheets to be inserted are less than six inches in length but greater then four inches in length . in the configuration of fig2 c , walls 24 are spaced 71 / 8 apart , and four pusher members , denoted 28a , 28b , 28c and 28d are employed . they are spaced ten inches from one another on a forty inch chain means . this configuration is used when the sheets are four inches or less in length . as indicated in fig2 d , each pusher member is pivotally mounted to chain means 28 . as indicated in fig1 machine 10 further includes third elongate table means or envelope loading station 30 having a longitudinal axis disposed transversely to the longitudinal axis of first table means 12 and second table means 16 . third table means 30 includes an envelope hopper 32 at a first end thereof , said first end being in longitudinal alignment with first table means 12 . third table means 30 further includes an envelope flap - opening station 34 , a sheet insertion station 36 , an envelope closing station 38 , and an envelope ejection station 40 . sheet insertion station 36 is disposed in longitudinal alignment with second table means 16 . a conveyor belt , not shown , is rotatably mounted in first table means 12 so that its forward - traveling section is substantially flush with the top surface of said table means 12 . it carries a long queue of envelopes 14 in the direction indicated by single - headed directional arrow 42 , said arrow indicating said direction of forward travel . as best understood in connection with fig3 when an individual envelope 14 reaches the end of table 12 , it follows a downward path of travel having a rounded ninety degree bend . this path of travel places it in envelope hopper 32 which has substantially the same height or depth as an envelope hopper of the prior art . however , the horizontal queue of the envelopes atop the conveyor means of first table 12 enables a machine operator to place thousands of envelopes atop said conveyor means without adding to the pressure or weight bearing down on the lowermost envelope in hopper 32 . moreover , the pressure applied to the lowermost envelope does not change as the length of the queue of envelopes grows shorter or longer . returning now to fig1 it should be noted that flap 44 of each envelope 14 is closed when it is in hopper 32 . a stationary flap opener means 46 in the form of a curved rod has a proximal end 46a positioned below the plane of third table means 30 and a distal free end 46b disposed in the path of travel of each flap 44 as the envelopes are sequentially pulled from the bottom of hopper 32 . thus , rod 46 mechanically displaces each flap 44 into a fully open position ; as indicated in fig4 each flap 44 is rotated more than one hundred eighty degrees when it is fully open . the lowermost envelope in hopper 32 is engaged at its inboard end by a clamp 48 ( see fig1 and 4 ) having a pair of opposed jaws that open and shut . when open , clamp 48 receives or releases an inboard end of the lowermost envelope and when closed , said clamp engages said inboard envelope . as perhaps best understood in connection with fig4 the clamp at position 48a is open and ready to receive between its opposed jaws the inboard end of an envelope 14 that is being removed from envelope hopper 32 . the clamp at position 48b is closed and has pulled a lowermost envelope out of hopper 32 and past curved rod 46 and thus flap 44 has been fully opened so that it lies in a plane more than one hundred eighty degrees from its initial , closed position . the clamp at position 48c has pulled an envelope to sheet insertion station 36 where at least one sheet of paper or similar item is inserted into an opened envelope . water in elevated reservoir 50 is conveyed under gravity feed to brush 52 by hose 54 ; the clamp in position 48d has pulled an envelope , with flap 44 still open , under said brush to moisten the adhesive on the inside of the flap . a second curved rod 56 has an inboard end 56a disposed below the plane of the envelopes on table 30 and an outboard end 56b ( fig1 ) disposed above said plane so that the flap is closed as soon as the moisture is applied . roller 58 turns in the direction indicated by arcuate arrow 59 in fig4 and presses on the closed flap to seal the envelope . the clamp in position 48d opens to release the envelope when an actuator 49 that depends therefrom ( see fig4 a ) encounters roller 64 and the envelope is propelled to a collection table , not shown , that would be positioned at the left side of fig4 . the clamp at position 48d is approaching the position of the clamp at position 48e when the envelope is propelled to the collection table , because the clamps follow a path of travel defined by sprocket chain 60 ( or other suitable belt means ). the direction of travel of sprocket chain 60 is denoted by directional arrows 61 and 62 . gear 64 is a driving gear and gears 65 , 66 and 67 are idler gears . a first cam , not shown , forms a part of a well - known mechanism that takes envelopes out of envelope hopper 32 . a second cam 69 selectively opens and closes the clamp at position 48a either directly or by means of bell crank 71 or other suitable linkage means as depicted in this particular embodiment . a third cam , not shown , selectively opens and closes the clamp at position 48c so that the envelope can be opened for the sheet insertion process and immediately closed thereafter . a fourth cam is also employed to operate the insert entering finger assembly , disclosed hereinafter . thus , there are only four cams in the inventive machine , whereas the known machines have about twenty cams . as indicated in the detailed drawings denoted fig4 a and 4b , each clamp is maintained in a normally closed configuration by a bias means such as spring 47 , and each clamp has an actuator 49 that opens the opposed jaws of the clamp when displaced . motor 68 drives belt 73 that in turn rotates shaft 72 of indexing box 74 . the first one hundred eighty degree rotation of shaft 72 results in a one hundred twenty degree rotation of wheel 76 . the second one hundred eighty degree rotation of shaft 72 results in no rotation of wheel 76 , i . e ., there is a dwell of wheel 76 during said rotation of shaft 72 . the arrow denoted t1 in fig4 indicates the linear travel of a clamp 48 for each rotation of wheel 76 . this rotate and dwell pattern is a three stop , three position output , i . e ., for each 360 degrees of input there is 120 degrees of output ; 180 degrees of the input is dwell . indexing box 74 eliminates any need for a stepper motor , i . e ., the output shaft of motor 68 rotates continuously , in the absence of starting and stopping . fig5 diagrammatically depicts the control means for novel machine 10 . in this example , there are six sheet feeders 18a - f , as distinguished from the five sheet feeders depicted in fig2 . prior art sheet feeders , as mentioned earlier , are controlled as a group by a single motor means . thus , each sheet feeder deposits one sheet on flighted conveyor 22 for each cycle of operation . however , if a customer wants sheet feeder 18a to deposit two sheets for every sheet deposited by sheet feeder 18b , the single motor assembly of the prior art cannot be used . this invention provides a single motor means such as motor means 82 ( fig5 ) for use when each sheet feeder 18a - f is operating at the same speed as the other sheet feeders . it also includes a plurality of motors such as motors 82 and 84 and others so that a motor is dedicated to each sheet feeder 18a - f whereby each sheet feeder is independently controlled and run at a preselected speed . thus , if it is desired to operate one or more of the sheet feeders at two times , three times , or more times the speed of the other sheet feeders , such differing speeds of operation can be accomplished . in a six sheet feeder machine , there could be four regular motors , one stepper motor and one high speed motor . any combination of motors is available ; the motors depicted in fig5 are merely exemplary . all motors in machine 10 are under the control of novel control means or programmable logic controller ( plc ) 86 which is electrically connected to monitor 88 and control panel 90 . pushbutton safety switch actuator 92 is electrically connected in series to push - button switch actuators 94 and 98 so that said switch actuators do not work unless switch actuator 92 is activated simultaneously . depressing switch actuators 92 and 98 at the same time starts the novel machine . depressing switch actuators 92 and 94 at the same time jogs the machine , i . e ., the machine runs only for so long as the depression of said switches is maintained . depressing switch actuator 96 re - sets the controls of the machine but does not result in operation of any moving parts . accordingly , it is not in series with safety switch 92 . push - button switch actuator 100 is the stop switch and is also not in series with safety switch actuator 92 . the physical spacing of safety switch actuator 92 from switch actuators 94 and 98 is a well - known safety feature that ensures that the machine operator &# 39 ; s hands are safely away from moving parts when the machine is operated . plc 86 is programmable so that sheet feeders 18a - f are individually controllable . referring now to fig6 when an envelope 14 arrives at sheet insertion station 36 , air is blown thereinto to open said envelope so that insert entering finger 85 may be inserted thereinto to hold the envelope open during the sheet insertion process . the air , denoted 83a , flows out of a plurality of parallel , horizontally disposed air jets 80 ( fig6 a ) that are formed in insert plate 83 , said insert plate being flush with the top surface of table means 16 . the jets have a longitudinal axis parallel with the longitudinal axis of table means 16 and they are transversely spaced apart from one another as indicated in fig6 a so that said jets supply air along the entire extent of the envelope to be opened . a sensor means 37 ( fig5 ) detects the presence of an envelope at sheet insertion station 36 and actuates a pneumatic means , not shown , that delivers the brief puff of air , from said jets , into said envelope so that it is momentarily opened . an item such as a sheet of paper or a small stack of papers 26 in inserted , by pusher member 28a , into the envelope during the brief time it is open . thus , each envelope 14 is already open by the time it arrives at sheet insertion station 36 . this enhances the productivity of machine 10 because prior art machines deliver closed envelopes to a sheet insertion station as mentioned earlier . in the prior art machine , envelope - opening suction cups are brought down to grab each closed envelope as it arrives at the sheet insertion station . significantly , the envelope must be at a complete stop before it can be engaged by the suction cups . after the sheet insertion , the suction cups must then be disengaged before the envelope can resume movement . by eliminating the suction cups and the mechanical means for lowering them into engagement with each envelope and for thereafter lifting them out of said engagement , the mechanical complexity of the machine is reduced and the cycle time for performing a sheet insertion is substantially reduced . element 85 in fig6 is known in the industry as an insert entering finger ; it holds an open envelope in its open position during the insertion process . it also serves as a guide means for guiding the sheets into the envelope and for holding said sheets down . this invention improves a conventional insert entering finger by adding air jets formed in the leading edge of said insert entering finger 85 to enhance its effectiveness . a blast of air from said jets is denoted 85a ; note the downward direction of the air blast which serves to hold the sheets down . if an envelope is not delivered to sheet insertion station 36 , or if an incomplete set of sheets is delivered to said station , as sensed by sensor means 39 ( fig5 ), a burst of air delivered by upwardly pointing air jets , centered in openings 81 , 81 , ejects the set of sheets or incomplete set of sheets out of said station 36 . the air is supplied by a pneumatic means , not shown , that is actuated by said sensor means 39 . this ejection means allows machine 10 to continue operating when the above - mentioned events occur . prior art machines must be stopped when such events occur . the provision of an ejection means at the point of sheet insertion was heretofore unknown . sensor means 41 , also depicted in fig5 senses the level of envelopes in envelope hopper 32 and re - starts the conveyor belt carried by the first table means to replenish said hopper with additional envelopes in the absence of operator intervention . sensors are also provided for each sheet feeder to start and stop said feeders to stage the pieces of paper . unlike the pivotally - mounted , reciprocating pusher means of the prior art , novel pusher assembly 28 is provided in the form of a plurality of pusher members that follow a path of travel that forms a closed loop . as mentioned above , there are two , three or four sets of pusher members , depending upon the length of the sheets being inserted , and each set of pusher members may include one or more push arms disposed in transversely spaced apart relation to one another , as best indicated in fig1 . the number of push arms within each set may be varied because the number of push arms in a set is not critical . a top view of the pusher member sets is provided in fig1 and a side view thereof is provided in fig2 . arcuate arrow 29 in fig2 indicates that the pusher member sets retreat from sheet insertion station 36 for the first half of their path of travel and advance toward said station 36 during the second half of said path of travel . it is during the second half of said path of travel that a set of pusher members such as pusher set 28c ( fig2 b ) engage a sheet of paper or a short stack of papers and push said sheet or stack towards the envelope insertion station 36 . pusher members 28d are depicted in said fig2 b pushing a sheet or stack of sheets into opened envelope 14 during the release of the above - mentioned puff of air . note that the sets of pusher members in the retreat section of the path of travel are disengaged from said sheets but are rotating into position to sequentially perform the functions being performed by the advancing pusher members . parallel , longitudinally extending grooves , not shown , are formed in insert plate 83 ( see fig6 ) and the respective lowermost ends of pusher members 28a - d are slideably received within said grooves when the pusher members move toward envelope insertion station 36 . this enables the pusher members to extend slightly below said top surface to ensure substantially problem - free insertion of the sheets into the envelopes . there is one groove for each pusher member . fig7 discloses an alternative means for delivering envelopes to envelope hopper 32 . this means does not include elongate first table 12 . instead , a high capacity demand feeder 90 delivers envelopes to hopper 32 to ensure that said hopper does not run out of envelopes . feeder 90 is canted from a vertical axis as depicted and may be provided with other means as well to ensure that the lowermost envelope in the stack of envelopes does not carry the weight of all envelopes above it . the novel high capacity demand feeder of fig7 delivers envelopes to hopper 32 in a direction normal to the direction of arrow 42 in fig1 i . e ., the envelopes are displaced in a transverse direction , entering edgewise into said hopper . the high capacity demand feeders heretofore known feed envelopes in the direction of said arrow 42 . note that fig7 shows two feeders 90 in flanking relation to envelope hopper 32 ; this is intended merely to indicate that a single feeder 90 may be placed in either side of said hopper 32 . this invention represents a major breakthrough in the art of machines that insert sheets into envelopes . being drawn to a pioneering invention , the claims that follow are entitled , as a matter of law , to broad interpretation to protect the heart or essence of the invention from piracy . it will thus be seen that the objects set forth above , and those made apparent from the foregoing description , are efficiently attained . since certain changes may be made in the foregoing construction without departing from the scope of the invention , it is intended that all matters contained in the foregoing construction or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense . it is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described , and all statements of the scope of the invention which , as a matter of language , might be said to fall therebetween .