Abstract:
An aquatic propulsion device includes an elongate member secured to a forearm support and a paddle. The paddle and elongate member include a grip positioned such that a person may place their forearm in the forearm support and reach and hold onto the grip. While wearing the aquatic propulsion device, the person may perform power and/or return strokes using their forearm and hand, such that the forearm support, the elongate member, and the paddle move in tandem with the forearm and hand. The aquatic propulsion device is characterized by a center of water displacement that extends beyond the hand, away from the forearm. Additionally, a leading edge of the paddle is substantially inline with the hand and forearm.

Description:
FIELD OF INVENTION 
     This invention relates to; human powered devices for enhancing propulsion in, through, or upon water. 
     BACKGROUND 
     Human powered aquatic propulsion devices are often used for purposes of sport, recreation, exercise, training, rescue, and/or rehabilitation. Aquatic propulsion devices exist in different configurations, some of which rely primarily upon lower body strength and others that primarily rely upon upper body strength. Aquatic propulsion devices that rely upon upper body strength frequently utilize hand paddles as a propulsion enhancement mechanism. Examples of aquatic propulsion devices utilizing hand paddles are given in U.S. Patent Nos. 3,913,907; 3,922,740; 5,658,224; 5,288,254, and 4,913,418. Some aquatic propulsion devices utilize paddles or fins attached to a forearm, such as those described in U.S. Patent Nos. 4,521,011 and 3,786,526. 
     Hand paddles enhance aquatic propulsion by displacing a greater amount of water for a given movement than would result from hand movement alone. Aquatic propulsion may also be enhanced through the leveraging of force over a distance greater than that defined by a human limb movement alone. As an example, the use of oars for rowing boats leverages force over distance, thereby increasing the efficiency of human work. Unfortunately, the hand and/or forearm paddles mentioned above fail to incorporate useful leveraging action. Such hand and/or forearm paddles may be characterized as providing a water displacement distance that is the same as or less than the movement of a hand, thereby undesirably limiting the extent to which they may enhance aquatic propulsion. 
     A hand paddle disclosed in U.S. Patent No. 4,509,744 extends a center of displacement slightly beyond a hand, directly away from an arm. However, this invention is designed only as an exercise device to be utilized against the resistance of water. Due to design shortcomings, this and similar types of inventions would be of limited use relative to enhancing aquatic propulsion. 
     The torque generated by water resistance at the center of displacement and the force applied by a hand increase linearly with the distance between the center of displacement and the hand. This force must be countered by an equal but opposite force to keep a paddle substantially in plane with the hand and arm. 
     U.S. Patent No. 4,509,744 discloses a hand paddle that uses a wrist guide, which reduces the turning moment about a user&#39;s wrist. Because of the proximity of the wrist to the hand relative to the distance from the hand to the center of water displacement, leveraged forces can become very great at the wrist. A wrist is typically bony and uneven on its top side, while its underside is soft, having many unprotected moving tendons. Thus, the wrist is not suitable for countering torque generated by an extended center of water displacement. The hand paddle design disclosed in U.S. Patent No. 4,509,744 is therefore problematic relative to the stresses imposed upon a user&#39;s wrist. 
     A paddle may be defined as having a leading edge, which is the edge that first ‘cuts’ though the water on the return or non-power stroke during swimming. As the perpendicular distance of a paddle&#39;s leading edge relative to a hand or arm increases, the paddle&#39;s steering radius undesirably increases, and a user&#39;s margin for error and ability to perform directional adjustments decrease. This effect is similar to using the rear wheels of a car for steering. Unfortunately, prior hand and arm paddles fail to properly position the leading edge of the paddle relative to a user&#39;s arm or hand, thereby limiting their ease of use and effectiveness. 
     In addition to the aforementioned problems, the. enhanced water displacement of hand and arm paddles can be disadvantageous or dangerous when hands and arms need to be used for actions other than swimming, for example, when taking pictures, picking up objects, or adjusting, scuba or snorkeling apparatus. Removal of prior art hand and/or arm paddle assemblies can be problematic since such assemblies encumber both hands and arms. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, an aquatic propulsion device comprises a forearm support to be worn on a forearm of a person; an elongate member having a first end secured to the forearm support; and a paddle secured to a second end of the elongate member. A combination of the elongate member and the paddle include a grip positioned so that a person, when placing their forearm in the forearm support, may reach and hold onto the grip with a hand. The person may move the grip with the hand such that the forearm support, the elongate member and the paddle move in tandem with the hand and the forearm. A combination of the forearm support, the elongate member, the grip, and the paddle is characterized by a center of water displacement extending beyond the hand, away from the forearm. 
     Extending the distance between the center of water displacement and the grip directly away from the hand and forearm advantageously enhances aquatic propulsion by leveraging force over a distance or arc length greater than that defined by hand movement alone. A constraining action between the forearm support against or upon the forearm may counter a rotational moment of the paddle about the grip. The distance between the grip and the forearm support, through leveraging, significantly reduces the force required to counter the rotational moment of the paddle about the grip relative to a force that would otherwise be required proximate the hand or wrist. 
     Another aspect of the invention teaches that a leading edge of the paddle is substantially inline with the hand and forearm, thereby enhancing a user&#39;s ability to perform directional adjustments. For safety and convenience, in an additional aspect of the invention, the forearm support partially encloses the forearm, such that release of the hand grip facilitates essentially free release of the aquatic propulsion device from the person. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a drawing illustrating a diver using an aquatic propulsion device constructed in accordance with the present invention. 
     FIG. 2 is a perspective view showing a user&#39;s arm position while holding an aquatic propulsion device constructed in accordance with the present invention. 
     FIG. 3 is a perspective view of an aquatic propulsion device constructed in accordance with the present invention. 
     FIG. 4 is an exploded perspective view of an aquatic propulsion device constructed in accordance with the present invention. 
     FIG. 5 is a side view of an aquatic propulsion device folded into a storage position. 
     FIG. 6 is a side view showing structural elements that facilitate the folded storage position of FIG.  5 . 
     FIG. 7 is a perspective view showing exemplary first, second, and third paddle flex patterns. 
     FIGS. 8A,  8 B, and  8 C are side views respectively showing a first, a second, and a third exemplary rotational orientation of the aquatic propulsion device relative to a user&#39;s arm rotation. 
     FIG. 9 is a perspective view of a first alternate embodiment of an aquatic propulsion device constructed in accordance with the present invention. 
     FIG. 10 is a perspective view of a second alternate embodiment of an aquatic propulsion device constructed in accordance with the present invention. 
     FIG. 11 is a perspective view showing structural elements that facilitate a disengaged position for the aquatic propulsion device of FIG.  10 . 
     FIG. 12 is a perspective view showing a third alternate embodiment of an aquatic propulsion device constructed in accordance with the present invention. 
     FIG. 13 is a perspective view showing a fourth alternate embodiment of an aquatic propulsion device constructed in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 of the accompanying drawings illustrates a person  30  using an aquatic propulsion device  32  according to an embodiment of the invention. The aquatic propulsion device  32  comprises a paddle  34 , a hand grip  36 , a forearm-member mount  38 , an elongated forearm member  40 , and a forearm support  42 . In use, the person  30  inserts an arm  52  into the forearm support  42 , and uses a hand  54  to hold or grasp the hand grip  36 . The person  30  alternately employs or performs propulsive, or power, strokes, followed by return, or non-power, strokes with the present invention to propel themselves through water. 
     Relative to propulsive strokes, movement of the arm  52  and hand  54  along the general direction of a propulsive axis, arc, or travel path  60  applies a force to the hand grip  36 . This force in turn causes the paddle  34 , which is oriented or held generally perpendicular to the propulsive axis  60  during the propulsive stroke, to displace a significant amount of water along the direction of the axis  60 , thereby propelling the person  30  forward. The person  30  may adjust the particular orientation of the axis  60  by rotating their arm  52  and hand  54 , which in turn may adjust the direction of propulsion during use. 
     Relative to return strokes, movement of the arm  52  and hand  54  along a return path (not shown) such that the paddle  34  is held or oriented generally parallel to the return path to minimize the amount of water displaced by the aquatic propulsion device  32  effectively returns the aquatic propulsion device  32  to a position from which another power stroke may originate. Those skilled in the art will understand that a return stroke may generally retrace some or all of a power stroke, and that a return stroke may be used to reorient the aquatic propulsion device  32  to a new position prior to a power stroke. 
     Referring also now to FIG. 2, a perspective view shows an aquatic propulsion device  32  supporting a user&#39;s arm  52 . The forearm support  42  may be generally u-shaped, and includes a support bottom  44 , a support front  46 , a support back  48  and a support opening  50 . The support bottom  44  is secured to the elongated forearm member  40 , and the support front  46  and support back  48  are secured to the support bottom  44 . Depending upon particular embodiment details, the support front  46  and/or the support back  48  may form a single, integral unit with the support bottom  44 . The support opening  50  is formed by a space between the support bottom  44 , the support front  46  and the support back  48 . A person  30  using the present invention inserts a forearm  56  into the support opening  50 , such that the forearm  56  is positioned against or upon the support bottom  44 ,;the support front  46 , and the support back  48 . 
     Opposing ends of the hand grip  36  are secured to the paddle  34 . One end of the forearm member mount  38  is secured to the paddle  34 , and an opposing end of the forearm member mount  38  is secured to one end of the elongated forearm member  40 . In response to a person&#39;s hand  54  applying a force against the hand grip  36  along the axis  60 , water resists the movement of the paddle  34  and creates a resistive force  62 . The resistive force  62  may be effectively characterized by a resistive center  64 . Increasing the distance between the resistive center  64  and the hand grip  36  directly away from the arm  52  advantageously enhances aquatic propulsion by leveraging force over a distance or arc length greater than that defined by hand movement alone. As an analogy, the use of paddles for rowing canoes leverages force over distance, thereby increasing the efficiency of human work. The present invention&#39;s leveraging of force significantly enhances a user&#39;s propulsion through water relative to prior types of devices such as conventional hand paddles. 
     The resistive force  62  at the resistive center  64  generates a rotational moment  66  about the hand grip  36 . Those skilled in the art will understand that movement of the paddle  34  along or about the rotational moment  66  should generally be restricted or limited to maximize the amount of water the paddle  34  displaces. 
     Through the aforementioned leveraging action, the torque generated by the rotational moment  66  proximate the hand  54  may be quite significant, and thus the hand  54  alone may have difficulty countering the rotational moment  66 . The present invention addresses this situation via the forearm support  42 . In particular, the support back  48  provides a surface capable of bearing pressures applied by the forearm  56  to counter the rotational moment  66  around the hand grip  36 . The distance between the hand grip  36  and the forearm support  42  reduces the leveraging action of the rotational moment  66  proportional to the distance between the hand grip  36  and the resistive center  64 . Therefore, the force applied by the support back  48  against the forearm  56  is significantly reduced relative to a force that would otherwise be required proximate the hand  54  or wrist. Moreover, a person&#39;s forearm  56  tends to be muscular, and can therefore more easily and comfortably bear the force applied by the support back  48 . One skilled in the art will recognize that movement of the arm  52  and the hand  54  opposite to the axis  60  results in the generation of oppositely-directed forces that can be countered to the same effect and advantage by the forearm  56  against the support front  46  of the forearm support  42 . 
     At times, a person&#39;s arms  52  and hands  54  may be required for actions other than aquatic propulsion, for example, taking pictures, picking up objects, and/or adjusting scuba or snorkeling gear. In one embodiment, by simply releasing the hand grip  36 , the resistive effect of water and/or gravitational forces allow the user  30  to freely remove their arm  52  and hand  54  from the aquatic propulsion device  32 . The present invention may advantageously provide simple, rapid, and unaided removal of the arm  52  and hand  54  to maximize both safety and convenience. 
     Referring also now to FIG. 3, a perspective view shows additional details of an aquatic propulsion device  32  constructed in accordance with the present invention. The embodiment shown in FIG. 3, includes a tether  84 , which may be employed to prevent the aquatic propulsion device  32  from drifting, floating, sinking or otherwise undesirably moving away when the person  30  releases or disengages their hand  54  and arm  52  from the aquatic propulsion device  32 . The tether  84  may be added to or included in any particular embodiment of aquatic propulsion device  32 . In one embodiment, a first end of the tether  84  may be secured to the elongated forearm member  40  using a tether pin  86 . An opposing end of the tether  84  may be secured to an arm strap  88 . The arm strap  88  may be secured as desired along the arm  52  using, for example, a Velcro strap, a buckle, or other attachment mechanism as would be well understood by one skilled in the art. In another embodiment, the tether  84  may be secured to the person  30  at a swimming suit, a waist belt, a diving vest, a life vest or a wet/dry suit using a Velcro strap, a buckle, a clip, a carabiner or other type of conventional attachment mechanism. 
     FIG. 3 additionally shows that the paddle  34  includes a leading edge  70 ; a rigidifying support  72  having a trailing side  74 ; a resistive surface  76 ; a spacing hole  78 ; a spacing recess  80 ; and a hand grip hole or opening  82 . The rigidifying support  72  lies along or upon the paddle&#39;s leading edge  70 . The resistive surface  76  may be secured to the paddle  34  along the rigidifying support&#39;s trailing side  74 . Those of ordinary skill in the art will readily understand that the rigidifying support  72  and resistive surface  76  may be constructed in alternative shapes and designs, including variations in widths and lengths. Those skilled in the art will further understand that the rigidifying support  72  may be divided or “splayed out” into multiple generally-rigid members or “fingers” across the resistive surface  76 , in a manner similar to the fingers or divisions found in a bat wing. 
     The spacing hole  78  and the spacing recess  80  may be cut, drilled, formed, or otherwise placed in the rigidifying support  72  proximate the hand grip  36  to focus water displacement on the resistive surface  76 . This, in turn, moves the resistive center  64  further away from the hand grip  36 , advantageously increasing the efficiency of aquatic propulsion. The hand grip hole  82  may be cut, drilled, formed or otherwise placed in the rigidifying support  72  to allow for comfortable and secure placement of the hand  54  around the hand grip  36 . 
     The paddle&#39;s leading edge  70  may be defined as an edge or side that first ‘cuts’ or ‘slices’ through the water on a return or non-power stroke during swimming. Referring again to FIG. 2, the paddle  34  may be further characterized as having a steering radius  68 , defined by a perpendicular distance from the leading edge  70  to a line  69  running through the hand  54  and the forearm  56 . The present invention teaches that the leading edge  70  should be inline or generally proximate and parallel to the line  69  running through the hand  54  and the forearm  56 . In other words, the steering radius  68  should not typically extend much past the hand  54 , thereby enhancing a user&#39;s ability to perform directional adjustments. When the steering radius  68  is small, the effect is similar to steering an automobile with its front wheels; however, as the steering radius is extended, the effect is similar to steering an automobile with its rear wheels. The small steering radius  68  provided by the present invention advantageously aids user control, in contrast to prior types of devices directed toward enhancing human propulsion in water. In an exemplary embodiment, the steering radius is approximately three inches. 
     The hand grip  36 , the forearm member mount  38 , the elongated forearm member  40 , the forearm support  42  and the rigidifying support  72  may be constructed using material that is rigid, strong, light weight, UV protected and corrosion resistant, as well as attractive and hydrodynamic. In some embodiments, it may be advantageous for the rigidifying support  72  to have some amount of flexibility in order redirect forces, channel water flow and relieve stress. Many conventional types of plastics, rubber, metal alloys or the like would be suitable for construction of the present invention. For example, High-Density Polyethylene (HDPE), Aluminum, Titanium, and/or Carbon fiber materials may be employed in construction of the present invention. 
     The resistive surface  76  may be constructed using material that is flexible, strong, light weight, UV protected and corrosion resistant, as well as attractive and hydrodynamic. Many conventional types of plastic, rubber, metal alloys or the like, would be suitable, including one or more of the aforementioned materials. The desired flexibility of the resistive surface  76  may depend on the particular application of the present invention, and may be determined by material type and/or material thickness. For example, a novice user  30  may desire greater flexibility to reduce fatigue, while a more experienced user  30  may want less flexibility for higher performance. The resistive surface  76  may be manufactured. from the same material as the rigidifying support  72 , but typically manufactured thinner in order to provide a desired amount of flexibility. This allows the paddle  34  to be manufactured using a single injection molding process. The boundary between the rigidifying support  72  and the resistive surface  76  may be abrupt, or a gradual taper as best suits any given application. Alternatively, the resistive surface  76  may be constructed using a material different from that of rigidifying support  72 , and laminated, bolted, welded, or otherwise secured to the rigidifying support  72 . 
     The desired buoyancy or density of the material or materials used to manufacture the aquatic propulsion device  32  may be selected based upon application. For example, scuba and underwater applications may require materials characterized by neutral or slightly negative buoyancy, while snorkeling and surface water applications may find materials providing increased buoyancy advantageous. 
     As with many manufactured products, cost, manufacturability, and intended application relative to any given choice of materials must be considered. The aforementioned elements may be manufactured from conventional materials using conventional injection molding, machining and/or similar techniques. 
     FIG. 4 illustrates an exploded view of an aquatic propulsion device. 32  constructed in accordance with the present invention. A rotational attachment screw  100  may be used to secure the forearm member mount  38  to the elongated forearm member  40 . The tether pin  86  may also be used to further secure the forearm member mount  38  to the elongated forearm member  40 , in addition to securing one end of the tether  84  to the aquatic propulsion device  32 . 
     The elongated forearm member  40  comprises a front elongated member  102 , a back elongated member  104 , a rotational stop  106 , a spacing component  108  and a set of forearm member screws  11   0 . The forearm member screws  110  may be used to secure the front elongated member  102  to a first side of the rotational stop  106  and a first side of the spacing component  108 . The forearm member screws  110  may continue through the rotational stop  106  and the spacing component  108 , and may also be used to secure an opposing side of the rotational stop  106  and an opposing side of the spacing component  108  to the back elongated member  104 . A set of forearm support screws  112  may be used to secure the support bottom  44  to the elongated forearm member  40 , such that the support front  46  and the support back  48  are slidably adjustable to comfortably and securely fit the forearm  56 . Those skilled in the art will recognize that various embodiments of the aquatic propulsion device  32  may rely upon additional, fewer, and/or different types of securing elements than those shown in FIG.  4 . 
     FIG. 5 shows an aquatic propulsion device  32  folded into a storage position. The storage position reduces overall length to facilitate ease of transportation and/or storage. The elongated forearm member  40  and forearm support  42  may rotate around the rotational attachment screw  100  relative to the forearm member mount  38  and paddle  34 . In the folded storage position, the rotation of the elongated forearm member  40  and forearm support  42  is arrested or limited by the paddle&#39;s rigidifying support  72 . 
     FIG. 6 shows an aquatic propulsion device in an exemplary partially-folded position, wherein the front elongated member  102  has been removed to expose the structural interaction of the forearm member mount  38  and the rotational stop  106 . In a fully extended or usage position, as illustrated in FIGS. 1 through 4, the rotation of the elongated forearm member  40  may be arrested. when the rotational stop  106  contacts a keyed stop  120  of the forearm member mount  38 . 
     FIG. 7 illustrates a first and a second resistive surface flex pattern  122 ,  123  that result when a person&#39;s hand  54  applies a force against the hand grip  36  along a first axis  60  and a second direction, axis, arc or travel path  61  that is generally opposite the first axis  60 , respectively. The magnitudes of the first and second flex patterns  122 ,  123  are dependent on  1 ) the amount of force applied to the hand grip  36  along the first and second axes  60 ,  61 , respectively; and  2 ) the rigidity and thickness of the material used to construct the resistive surface  76 . As mentioned above, increased flexibility may reduce a novice user&#39;s fatigue, while increased rigidity may increase power and control for a more experienced user. 
     FIGS. 8A,  8 B and  8 C are side views of an aquatic propulsion device  32  showing various degrees of a rotation orientation around the line  69  running through the hand  54  and the forearm  56 . Each of these rotational orientations is exemplified by rotating a user&#39;s hand  54  while leaving the forearm  56  and arm  52  in place. One skilled in the art will recognize that the rotational orientations illustrated in FIGS. 8A,  8 B and  8 C are for descriptive purposes only and represent an essentially infinite range of rotational orientations around the line  69 . Rotation of the aquatic propulsion device  32  around the line  69  may be used to  1 ) steer the aquatic propulsion device during the return or non-power stroke during swimming; and/or  2 ) adjust the exposure and thereby degree of water displacement by the resistive surface  76  during the power stroke while swimming. 
     FIG. 9 is an illustration. of an alternate embodiment of an aquatic propulsion device  32  in which the forearm member mount  38  and the elongated forearm member  40  are secured by construction &#39;as a single rigid forearm member  130 . This embodiment simplifies the construction and reduces the amount of material and components required manufacture the aquatic propulsion device  32 . Such an embodiment may also improve the hydrodynamic properties of the invention. However, the storage position, as shown in FIG. 5, is not possible in this embodiment. This alternative embodiment may be advantageous for applications where performance and cost outweigh the convenience of the storage position for transportation and storage. One skilled in the art will see that there are any number of embodiments relative to the construction of the elongated member mount  38  and the elongated forearm member  40 , including, but not limited to, an embodiment in which they are secured by bolts, latches and/or a telescoping mechanism, thereby providing some of the advantages of the single rigid forearm member  130  while allowing for detachment to facilitate transportation and/or storage. 
     FIGS. 10 and 11 illustrate another embodiment of the present invention in which the forearm support  42  includes a support top  132  to facilitate a full encircling of the forearm  56 . For purpose of example, the front elongated member  102  has been removed in FIGS. 10 and 11 to expose the structural interaction of the forearm member mount  38  and the rotational stop  106 . As can be seen in FIGS. 10 and 11, the forearm member mount  38  may rotate around the rotational attachment screw  100  unencumbered by the rotational stop  106 , thereby allowing the forearm member mount  38  and paddle  34  to swing out of the way of the hand  54  when the hand grip  36  is released. In such an embodiment, the tether  84 , as shown in FIGS. 3 and 4, is not necessary because when released, the aquatic propulsion device  32  is prevented from drifting, floating, sinking or otherwise undesirably moving away from the person  30  by the forearm support  42 . This embodiment may be advantageous when unimpeded movement of the forearm  56  and arm  52  are not required. Those skilled in the art will understand that in yet another embodiment, one or more portions of the forearm support  42  could comprise a strap, which may be implemented, for example, using Velcro™ or other material. 
     FIG. 12 illustrates an embodiment of an aquatic propulsion device  32 , as taught by the present invention, wherein the leading edge  70 , rigidifying support  72  and the resistive surface  76  have or include a downward taper  140  on an end opposing the hand grip  36 . The downward taper  140  curves down and past the line  69  running through the hand  54  and the forearm  56 ; that is, the downward taper  140  curves toward a line essentially parallel to the elongated forearm member  40 . The downward taper  140  significantly reduces an average or effective steering radius  67 , defined as an average distance between the line  69  and the leading edge  70 , thereby increasing control and reducing the torque required to make directional adjustment to the paddle  34  through the water on the return or non-power stroke while swimming. In an exemplary embodiment, the effective steering radius  67  is approximately one inch; and the downward taper  140  curves such that the vertical distance or offset between the leading edge  70  and a tip or end  77  of the paddle&#39;s resistive surface  76  is approximately four inches. Those skilled in the art will recognize that the effective steering radius  67  and the extent of the downward taper  140  may vary in accordance with particular embodiment details. 
     FIG. 13 illustrates yet another embodiment of the present invention, in which a bend  150  is formed in the rigidifying support  72 , thereby moving the resistive surface  76  out of a plane  152  formed by opposing ends of the hand grip  36  and the length of the elongated forearm member  40 . The bend  150  may be characterized by an angle  154  formed between the resistive surface  76  and the plane  152 . The angle  154  modifies the exposure of the resistive surface  76  to the water relative to the movement of the arm  52  during a power stroke while swimming. Various degrees of angle  154  may be advantageous for redirecting the resistive force  62  of the resistive surface  76  against the water in a more forward direction during a strongest portion of the arm&#39;s movement while swimming. This in turn may improve or enhance the aquatic propulsion properties of the present invention. In an exemplary embodiment, the angle  154  is approximately 15 degrees. Those skilled in the art will see that many different angles may be advantageous depending upon  1 ) the swimming application, such as, speed, distance, sport, or recreational use; and/or  2 ) the skill of the user. Those skilled in the art will also understand that an embodiment that incorporates the bend  150  may also incorporate the downward taper  140  shown in FIG.  12 . 
     While certain exemplary embodiments have -been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative and not restrictive of the current invention, and that elements of said embodiments may be combined in part or whole, and that this invention is not restricted to the specific constructions and arrangements shown and described since a wide range of modifications may occur by those ordinarily skilled in the art. The description herein provides for such modifications, and is limited only by the following claims.