fig1 is a side elevation view of a well jar 10 with a quarter section cut away to expose the internal parts thereof and which embodies the present invention . the well jar has telescoping inner tubular and outer tubular body elements 12 and 14 , respectively . the elements 12 and 14 are made of metal strengthened by heat treatment or by other known techniques , as required to prevent wear and breakage . a female internal thread type connector 16 is provided at the upper exposed end of the inner element 12 for connection to the lower end of an upper drill string . a pin or male external thread type connector 18 is provided on the extreme opposite lower end of the outer element 14 for connection to the lower drill string or an object stuck in a well bore . the center of the inner element 12 allows circulation of drilling fluid , such as mud . an interconnection is provided between the telescoping elements 12 and 14 for transmitting torque therebetween but allowing relative longitudinal movement between the telescoping elements . the connection is a spline connection 20 which includes inwardly longitudinally extending parrallel splines on the outer body element 14 and outwardly extending splines on the inner mandrel element 12 which allow relative longitudinal sliding movement . the spline connection 20 forms a portion of a torque drive section 22 allowing torque applied to the inner element 12 to be transmitted directly through the spline 20 to the outer element 14 , bypassing the outer parts such as the latch . a latch mechanism or section 24 has an intermediate element in the form of a generally tubular shaped latch member 26 which is rotatably mounted relative to and intermediate the inner and outer telescoping elements 12 and 14 . the intermediate latch member 26 is separated in a longitudinal direction from the outer element 14 by anti - friction thrust bearings 28 . two ring springs 29 and 30 prevent longitudinal movement of the intermediate member 26 relative to the outer telescoping element 14 while allowing relative rotation therebetween . to be explained in more detail , the intermediate member 26 has upper and lower parts 26a and 26b interconnected by a finger spline 51 . also the upper part 26a is connected to a torsion spring 48 by a finger spline 49 . the ring springs 29 and 30 load the upper and lower parts 26a and 26b to the left as seen in fig1 so as to maintain contact with thrust bearings 28 . bushings 32 rotatably mount the intermediate member 26 on the interior wall of the tubular shaped outer element 14 . the latch section 24 includes a plurality of latches 34 . each latch 34 includes a first part in the form of a roller 36 whose axis extends along a radius towards the center line of the well jar . each roller is rotatably mounted on a bearing spindle 37 which is affixed to the intermediate latch member . the bearing is positioned in a circular recess from the exterior of the tubular shaped intermediate latch member 26 . each latch includes a second part on the inner element 12 in the form of a cam 38 . the cam 38 is engageable with the roller 36 when latched so as to prevent relative longitudinal movement of the intermediate latch member 26 with respect to the inner element 12 and as a result prevents relative longitudinal movement of the telescoping elements 12 and 14 . to be explained in more detail , relative rotation of the intermediate latch member 26 and the inner element 12 to a breakaway position of the latch allows the roller 36 to move into a longitudinally elongated opening 39 in the inner element 12 , allowing the roller 36 ( and hence the intermediate latch member 26 ) to move longitudinally relative to the inner element 12 . also to be explained in more detail , the cam 38 has an inclined cam surface which , upon application of longitudinal force either in compression or in tension between the inner and outer telescoping elements 12 and 14 , causes the intermediate latch member 26 to rotate relative to the inner telescoping element 12 to the breakaway position of such latch parts . significant to the present invention there is provided a time delay means in the form of a timer section 40 . the timer section is connected between the intermediate latch member 26 and the outer element 14 and restrains relative rotational movement of the intermediate latch member 26 to the breakaway position for the latches for a preselected time interval of application of longitudinal compression or tension forces between the inner and outer telescoping elements 12 and 14 . details of the timer section will be described in connection with fig2 . a hammer section 42 has coacting impact faces 44 which strike or impact upon application of tension forces between the inner and outer telescoping elements 12 and 14 . impact faces 46 impact under compression applied between the telescoping elements 12 and 14 . resilient means in the form of the torsion spring 48 is provided in a torsion spring section 50 . the torsion spring 48 is connected by an involute spline 52 on a collar 54 to a spline on an annular extension 56 on the outer element 14 . the other end of the torsion spring 48 is affixed radially through the semicircular finger spline connection 49 to one end of the intermediate latch member 26 . the torsion spring 48 is preloaded about the longitudinal axis of the jar between the outer element 14 and the intermediate latch member 26 so as to rotate the intermediate latch member relative to the inner element 12 until the rollers 36 are bottomed in the cams 38 . as will become evident during the following discussion , relative rotation to the engaged position of the latch 34 can only occur when the inner and outer telescoping elements 12 and 14 are longitudinally moved to the position where the roller 36 and cam 38 of all latches 34 are longitudinally aligned . consider now in more detail the arrangement of the latches 34 . the latches 34 are arranged into groups 57 . four groups of latches 57 are positioned in a straight line extending longitudinally along the inner element 12 and the intermediate latch element 26 . each group has four latches 34 and each group is separated longitudinally with respect to the adjacent group . fig3 is an enlarged view of the inner mandrel 12 in the circled area indicated in fig1 . fig4 is a cross - sectional view of the inner mandrel 12 taken along line 4 -- 4 of fig3 . in addition to the four longitudinal groups seen in fig1 for each group seen in fig1 there are two additional groups of latches 57 angularly spaced at 120 ° increments around the inner mandrel 12 . the three angularly displaced lines of latches 34 are generally indicated by the three angularly displaced cams 38 and openings 39 depicted in the cross - sectional view of the inner element 12 shown in fig4 . as described above , each latch 34 contains a roller 36 mounted on the intermediate member 26 and a cam 38 in the inner mandrel 12 . referring to fig3 and 4 , each cam 38 , as best depicted in fig3 has two facing but diverging inclined surfaces 58 and 60 which diverge outwardly from a bottom 62 of the cam towards the elongated opening 39 . the surfaces 58 and 60 are inclined and diverge helically with respect to a center line 64 which is a tangent to the inner element 12 and is also perpendicular to the central axis of the inner element 12 . as depicted in fig1 and 4 , longitudinally elongated opening 39 is provided along each line of latches . the elongated opening 39 extends in a straight line along the inner element 12 in communication with the openings of each of the cams 38 disposed along the same longitudinal line . thus the torsion spring 48 urges the intermediate latch member 26 relative to the inner element 12 so that the rollers 36 engage the bottom 62 of the corresponding cam . consider briefly the operation assuming that there is no effect due to the time delay section 40 . when a longitudinal compressive force is applied between the inner and outer telescoping elements 12 and 14 , such as occurs when the outer element 14 is fixed and a downward force is applied to the upper drill string connected at 16 , each roller 36 will roll on the corresponding inclined surfaces 60 , forcing the intermediate latch member 26 to rotate in a clockwise direction as viewed from the connector 16 end of the jar . rotation continues until the roller 36 reaches a release or breakaway position where it is in the corresponding elongated opening 39 whereupon the inner element 12 drops downward free of the holding action of the rollers 36 . the downward movement of the inner element 12 continues until the coacting impact faces 46 strike , imparting a sharp downward impact force to a stuck object connected to the connector 18 . a similar action occurs when tension is applied between the elements 12 and 14 such as occurs when the outer element 14 is fixed and the inner element 12 is pulled upward . tension will cause each roller 36 to bear against the lower surface 58 of the corresponding cam 38 forcing the intermediate latch member 26 to rotate clockwise , viewed from connector 16 , until the rollers reach the unlatched or breakaway position and enter the corresponding elongated opening 39 . when this occurs the inner element 12 moves upwardly with respect to the intermediate latch member 26 and the outer element 14 with the rollers traveling in the corresponding opening 39 until the coacting impact faces 44 strike , imparting a sharp upward blow to a stuck object connected to the lower connector 18 . it will now be seen that the torsion spring 48 applies a torque which restrains the rotation of the intermediate latch member 26 relative to the inner and outer telescoping elements 12 and 14 until a minimum amount of longitudinal force is applied between the telescoping elements . by increasing the spring preload the amount of force required to rotate the intermediate latch member 26 to the breakaway position of the latches 34 is increased . refer now to the timer section 40 as best seen in fig2 . the timer means or section 40 is connected between the intermediate latch member 26 and the outer element 14 for restraining the relative rotational movement of the intermediate latch member 26 so that the breakaway position of the latch is not reached for a preselected time interval . the time interval is measured beginning with the time at which sufficient longitudinal force is applied between the telescoping elements to overcome the counteracting preload of the spring 48 . included therein is a converter 65 for converting the rotational movement of the intermediate latch member 26 into a linear longitudinal movement in the jar . the converter 65 includes a first part 66 on the intermediate latch member 26 and a second part 68 on a tubular part 73 . the parts 66 and 68 have facing inclined cam surfaces 66a and 68a , respectively , best seen in fig2 and 7 , which slidably engage each other . with this arrangement , rotation of the intermediate latch member 26 causes rotation of part 66 which in turn causes the surfaces 66a and 66b to rotate relative to each other . the part 68 is fixed so it cannot rotate and hence rotation of the surfaces 66a and 68b causes a force against inclined surfaces 68a and 68b causing a longitudinal movement of the part 68 to the right as viewed in fig2 and 7 . in this connection it should be noted that the intermediate latch member 26 will always move in the clockwise direction as viewed from the connector 16 end of the jar . timer section 40 has a substantially fluid - tight circular annular shaped chamber 72 which extends longitudinally in the jar for containing a fluid such as oil . the tubular part 73 includes a diametrically enlarged centrally located piston 74 which is elongated in a longitudinal direction in the jar and slidable in a longitudinal direction within the chamber . the piston 74 provides a substantially fluid - isolated chamber portion on each end thereof . the piston 74 , similar to the intermediate latch member 26 , is tubular shaped so that it slides along between the outer surface of the inner element 12 and the inside surface of the outer element 14 . at one angular position of the piston 74 there is provided a regulator 76 . the regulator 76 is a constant fluid flow type regulator that only allows a substantially constant rate of flow of fluid through the piston 74 from end 74a to end 74b over the expected variations in force created by the rotational to linear converter 65 under longitudinal force between the telescoping elements 12 and 14 . the regulator 76 is positioned in a passage 75 which extends between the ends 74a and 74b . in addition to the regulator 76 , which provides a substantially constant fluid flow from end 74a to end 74b , a check valve 78 is provided . the check valve 78 is located in a passage 80 extending between the ends 74a and 74b of the piston 74 . the check valve 78 blocks the flow of fluid from end 74a to end 74b but allows fluid to freely flow from end 74b to 74a . there is one additional constant flow regulator 76 in a separate angularly displaced passage 75 ( not shown ) identical to the one discussed above . also there are 13 additional check valves 78 separately positioned in 14 additional angularly displaced passages 80 ( not shown ), identical to the one described above . the passage 75 ( and the respective flow regulators 76 ) and the passages 80 ( and the respective check valves 78 ) are all connected in between the ends 74a and 74b of the piston in the same direction as the one described . the invention is not limited to any specific number of passages and regulators and check valves , the aforementioned being given by way of example . although not essential to the invention , 16 passages are positioned at equal angular positions and extend in between ends 74a and 74b , two of which are used as passage 75 ( with regulators 76 ) and fourteen of which are used as passages 80 ( with check valves 78 ). in one embodiment it has been found desirable to position the regulators 76 in the passages 75 adjacent the end 74b rather than the end 74a and place a screen over the passage at the end 74a in order to prevent foreign particles in the fluid from altering the time delay of the regulators . the regulators 76 are type 281 flosert , made by the lee company . a screen ( not shown ) covers the end of the regulator 76 facing to the right to prevent particles from entering the regulator . the check valves are size 187 made by the lee company . however , these devices are given by way of example and the invention is not limited thereto . the ends of the piston 74 are sealed between the outer wall of the piston 74 and the inner wall of the outer body element 14 by o - ring 81 positioned partially in an annular groove around the periphery of the piston 74 . the ends of the piston 74 are sealed in between the inner wall of the piston 74 and the outer wall of the inner element 12 by an o - ring 82 partially in an annular groove around the inner periphery of the piston 74 . in operation , when longitudinal force is applied between the telescoping elements 12 and 14 of sufficient magnitude to overcome the restraining force of the torsion spring 48 , the intermediate member 26 starts to rotate relative to the inner and outer telescoping elements 12 and 14 towards the breakaway position of latches 34 . however , the tendency to rotate is converted to a linear motion by the converter 65 thereby applying a force to the piston 74 tending to move it to the right hand end of chamber 72 as seen in fig2 . as a result , pressure builds up on the end 74a of the piston 74 . such flow of fluid is blocked by the check valve 78 but is permitted to flow by the regulator 76 through the passage 75 to the end 74b . the regulator 76 being a constant flow type regulator , allows a metered amount of flow to occur . after sufficient fluid has passed through the regulator to the end 74b of the piston to allow the piston 74 to move longitudinally to the point where the intermediate member 26 may rotate to the breakaway position of the latches , then the longitudinal movement of the telescoping elements 12 and 14 and the hammer action discussed above occur . a spiral compression spring 83 is positioned in the chamber 72 and bears against the end 74a of the piston 74 . the jar is reset after release of the latches by relatively moving telescoping elements 12 and 14 until the rollers line up with and rotate into engagement with the the corresponding cams under the force of the spring 48 . after this occurs the pressure between the parts 66 and 68 is relieved , allowing the spiral spring 83 to force the piston 74 to the left to its initial position where the end 74b abuts against the inwardly extending shoulder 14a of the outer body element 14 . the jar contains a static timer seal cartridge 85 . the seal cartridge 85 contains a male involute spline 84 which engages with a female spline formed on the interior of the outer body element 14 . the engaging splines 84 and 86 prevent the static timer seal cartridge 85 from rotating and in turn prevent the piston 74 from rotating under force created by the latches . as best seen in fig2 and 9 , the static timer seal cartridge 85 contains three longitudinally extending finger members 88 ( only two being shown in the figures ). the fingers 88 form segments of a circle and are spaced apart by equal angles . the end 74a of the piston 74 has three axially extending fingers 90 which also form segments of a circle and extend in an axial direction and in between the sides 88a of the fingers 88 so as to form a finger spline connection . the sides 88a and 90a of the fingers 88 and 90 , respectively , engage and , due to the rigid spline connection of the static timer seal cartridge 85 , prevent the piston 74 from rotating while allowing sliding longitudinal movement of the surfaces 88a and 90a of fingers 88 and 90 as the piston 74 moves in a longitudinal direction . the opposite end of the spiral spring 83 from the piston 74a bears against the longitudinal facing surface of the static timer seal cartridge 85 . an extension sub 92 carries the connector 18 at the lower end of the jar and at the opposite end of extension sub 92 a threaded male connector is provided for mating with a threaded female connector provided on the interior wall of the outer element 14 . the extension sub 92 forms a plug which engages the lower end of the static timer seal cartridge 85 and prevents it from moving axially out of the lower end of the jar . significantly , the fluid chamber 72 is elongated and extends in between the inner and outer telescoping elements 12 and 14 from the static timer seal cartridge 85 to a compensating seal section 93 and hence includes both the timer section 40 and the latch section 24 . as a result the same fluid which is used for controlling the timer section 40 is used for lubrication purposes in the latch section 24 . further , the latch section is positioned towards the splined connection 20 from the timer section 40 and is therefore positioned upwardly in the normally intended vertical position of the jar . as a result , lighter fractions of fluid created by bubbles , impurities , etc ., in the fluid will tend to rise in the chamber 72 away from the piston 74 thereby providing a more reliable , constant delay period . the compensating seal section 93 provides an expandable volume for the chamber 72 . the compensating seal section 93 includes a tubular shaped seal 94 positioned between the inner and outer telescoping elements 12 and 14 . outer o - rings 96 are provided in annular grooves around the outer surface of the seal member 94 in order to provide a fluid - tight seal between the member 94 and the inner surface of the outer element 14 . similarly , o - rings 98 are provided in recesses in the inner surface of the member 94 so as to provide a fluid - tight seal between the member 94 and the inner element 12 . with such an arrangement the member 94 is able to slide longitudinally between the inner and outer telescoping elements 12 and 14 and yet provide a fluid - tight seal for the chamber 72 . a spiral compression spring 100 is positioned in an annular space around the inner element 12 and is disposed in a longitudinal direction in the jar between an end of the member 94 and an inwardly extending shoulder 102 of the outer element 14 . the spring 100 urges the compensating seal member 94 towards an inwardly extending shoulder 104 of the outer body element 14 . as the fluid in the chamber 72 expands , the seal member 94 will be forced towards the inwardly extending shoulder 102 thereby expanding the volume within the chamber 72 . as the fluid volume decreases , the member 94 will move towards the shoulder 104 due to the force of the compression spring 100 . in order to facilitate the longitudinal sliding relative movement of the inner and outer telescoping elements 12 and 14 , four annular bushings 106 are affixed to the outer element 14 and between the inner and outer telescoping elements 12 and 14 at longitudinally spaced apart positions for providing a sliding bearing between the elements . openings 108 in the torque drive section 22 , openings 110 in the hammer section 42 , and openings 112 in the compensating seal section 93 , allow mud to circulate into the corresponding sections of the jar . although o - rings have been disclosed as seals herein it will be understood that other types of seals can be used as will be evident to those skilled in the art and are contemplated within the scope of the invention herein . to facilitate the assembly of the jar , the outer body element 14 is arranged into separate outer body parts 120 through 126 . each outer body part has a threaded connection to an overlapping portion of the adjacent outer body part . also the inner telescoping element 12 has an upper part 12a and a lower part 12b connected together by a threaded connector 130 which carries one of the impact faces 44 . prior to the major assembly , the bushings 106 for the inner telescoping element 12 are mounted using the retaining rings 107 . the tool joint seals 109 are inserted in the outer body connections . the seals 81 , 82 , 96 , 98 and 111 are mounted in the seal cartridge assembly 85 , the piston 84 and the seal member 94 . the regulators 76 ( and a screen for each regulator ) and the check valves 78 are affixed in the piston 74 as described above . the actual assembly of the well jar moving from left to right is as follows : the outer body part 120 is slid onto the upper part 12a of the inner telescoping element 12 , forming the spline connection 20 . the connector 130 is threaded onto the upper part 12a and is affixed thereto with screws . the following elements are then placed on the lower part 12b of the inner telescoping element 12 : outer body part 122 , the seal member 94 , the seal spring 100 , the outer body part 121 . the lower part 12b of the inner telescoping element 12 is then threaded into the remaining end of the connector 130 and affixed thereto by screws . the outer body parts 120 , 121 and 122 are then threaded together . the torsion spring 48 is positioned over the lower end 12b of the inner telescoping element 12 and the splines 56 thereof are engaged with the splines 52 on the outer body part 122 . the outer body part 123 is positioned over the lower part 12b of the inner telescoping element 12 and threaded with the outer body part 122 . the thrust bearing 28 is positioned over the front end of the upper part 26a of the intermediate member 26 . the upper part 26a of the intermediate member 26 is positioned over the lower part 12b of the inner telescoping element 12 and the finger splines 49 are engaged at the lower end of the torsion spring 48 . the torsion spring 48 is then preloaded by twisting the front 26a of the intermediate member 26 counterclockwise , as viewed from the right hand end of fig1 until the openings for the rollers in the upper part 26a of the intermediate member 26 line up with the corresponding openings 38 in the inner telescoping element 12 . the rollers 36 are then positioned into the upper part 26a of the intermediate latch member 26 , maintaining the preload for the spring 48 . the split bushings 32 are positioned on the upper part 26a of the intermediate latch member 26 and the thrust bearing assembly 28 and the ring spring 29 are positioned at the lower end of the upper part 26a of the intermediate latch member 26 . the outer body part 124 is slid over the upper part 26a of the intermediate element 26 and threaded together with the lower end of the outer body part 123 . the assembly is then unlatched and impact faces 46 touch . the thrust bearing 28 is then positioned over the upper end of the lower part 26b of the intermediate latch member 26 . the lower part 26b of the intermediate latch member 26 is then slid over the lower part 12b of the inner telescoping element 12 . the rollers are then positioned into the openings provided in the lower part 26b of the intermediate latch member 26 . the lower part 26b is progressively pushed to the left as seen in fig1 as the rollers are inserted in place until the finger spline 51 is fully engaged . the thrust bearing 28 and split ring spring 30 are positioned at the lower end of the lower part 26b . the outer body part 125 is then threaded into the outer body part 124 . the jar is subsequently latched and the tubular part 73 ( carrying piston 74 ) is positioned over the lower part 12b of the inner telescoping element 12 , fully engaging camming surfaces 66 and 68 . the spiral compression spring 83 is then positioned about the tubular part 73 and the static timer seal cartridge 85 is positioned about the lower part 12b , compressing the spiral compression spring 83 until the finger splines 88 and 90 are fully engaged . a slot 132 is provided at the right hand end of the static timer seal cartridge 85 in alignment with an opening 131 in the outer body part 125 . a retaining pin 128 is positioned through the opening 131 into the slot 132 thereby holding the cartridge 85 with the spring 83 preloaded . although the slot 132 is shown by way of example , it should be understood that an annular groove may be provided in the static timer seal cartridge for the pin 128 by appropriately extending the static timer seal cartridge to the right ( as seen in fig2 ) past the filler plug 134 . two - way vacuum filler plugs 134 and 138 , having threads on the exterior thereof , are respectively threaded into the static timer seal cartridge 85 and the end of the outer body part 122 which is adjacent to the outer body part 123 . the two - way vacuum filler plug 134 communicates with one end of the chamber 72 via the passage 136 . the two - way vacuum filler plug 138 communicates with the other end of the chamber 72 through an opening in the outer body part 122 and a relief in the adjacent annular bushing 106 . it will be noted at this point that the outer body part 126 which is a part of the extension sub 92 has not been positioned in place , leaving the filler plug 134 ( in the static timer seal cartridge 85 ) exposed . fig1 shows an enlarged cross - sectional view of the bushing 106 which is positioned under the two - way filler plug 138 at 1a of fig1 . fig1 shows an end view of the same bushing . as indicated , the bushing shown in fig1 and 12 contains two annular grooves extending around the circumference of the bushing , and four longitudinal grooves , the latter spaced 90 ° apart . depending on the direction in which the bushing 106 is inserted , one of the annular grooves is aligned with the two - way filler plug 138 thereby allowing fluid to freely flow into the annular groove through the longitudinal groove to opposite ends of the bushing . additionally the longitudinal grooves allow fluid to move within the chamber 72 from one end of the bushing to the other . the method and procedure for filling the well jar so as to completely fill the hydraulic timer section 40 and the latch mechanism chamber are quite important . in this connection it will be noted that the chamber 72 is separated into one chamber part at the right of piston 74 and a second chamber part at the left of piston 74 . the regulators 76 and the check valves 78 provide a restricted flow for fluid between the ends of piston 74 . additionally the regulators and check valves have a minimum cracking pressure at which fluid will flow therethrough . accordingly , care must be taken to ensure complete and uniform filling of the fluid into both chamber parts . referring to fig1 , a source of vacuum 150 is connected through a shutoff valve 152 to a tee fitting 154 . similarly , a reservoir 156 of fluid , of the type desired in chamber 72 , is connected through another shutoff valve 158 to another side of the tee fitting 154 . the remaining leg of the tee fitting 154 is connected through a second tee fitting 160 to the filler plugs 134 and 138 . the filler plugs 134 and 138 are rotated to a fill position leaving the lower o - ring of each plug out of the small hole of the corresponding opening so that a clear passage exists through both of plugs 134 and 138 into opposite ends of the chamber 72 . valves 152 and 158 are turned off so as to block the filler plugs from both of the sources 150 and 156 . subsequently the shutoff valve 152 is opened , applying vacuum through tees 154 and 160 to the filler plugs 134 and 138 , causing the chamber 72 to be evacuated . also the vacuum is left on long enough to not only create a vacuum but to draw out undesirable fluids remaining in the chamber 72 . with the vacuum maintained in the chamber 72 , the shutoff valve 152 is turned off and the valve 158 is turned on , allowing fluid in the reservoir 156 to flow through the tees 154 and 160 through the filler plugs 134 and 138 and into the chamber 72 until the fluid completely fills the chamber 72 from opposite directions . by this method it is possible to completely fill the chamber 72 with its many parts , shapes and angles with the restriction of the regulators and check valves , without leaving air bubbles . this is quite important since it is necessary to have a uniform fluid and a uniform fluid pressure for proper operation of the piston 74 . with the fluid reservoir connected to the ports , the filler plugs 134 and 138 are tightened down until the lower o - rings thereon are tightly fitted against the walls of the smaller diameter of the respective ports , thereby sealing the ports . the vacuum pump and fluid fill lines are then removed . the outer body part 126 forming the extension sub 92 is then threaded into place on the right hand end of the outer body part 125 and the retaining pin 128 is removed . the extension sub thereby forms a retainer to hold the seal cartridge in place . although an examplary embodiment of the invention has been disclosed for purposes of illustration , it will be understood that various changes , modifications and substitutions may be incorporated into such embodiment without departing from the spirit of the invention as defined by the claims appearing hereinafter .