Abstract:
A remotely actuated trail marker apparatus includes a transmitter unit designed to be carried by a hiker or hunter, which selectively broadcasts an interrogation signal throughout a predetermined range. One or more associated receiver units are adapted for pre-positioning at specific trail waypoints or a final destination. Each receiver unit generates a user sensible reply signal, such as self-illumination, in response to receiving the interrogation signal.

Description:
TECHNICAL FIELD 
   The present invention relates generally to apparatus employed for terrestrial navigation and particularly for defining a trail or destination in an otherwise remote locale. More particularly still, the present invention relates to markers suitable for pre-positioning at spaced waypoints to assist a user in retracing an earlier taken route. 
   BACKGROUND OF THE INVENTION 
   People often encounter great difficulty in marking trails when traveling in unfamiliar wooded areas or the like. The problem is particularly aggravated in the case of young or inexperienced individuals and/or those who have a poor sense of direction. Consequently, many people have become hopelessly lost because they failed to mark their trail and/or become totally confused in their sense of direction. 
   Heretofore, people traveling by foot relied on their sense of direction and/or memory (i.e. dead reckoning) when traveling over a trail in unfamiliar surroundings. Others have resorted to marking trails by breaking tree branches and/or setting up various signs by utilizing the natural materials found at hand, such as stones, branches, tree trunks and the like. However, the use of such natural material for marking trails frequently did not constitute a positive identification as such signs quickly lost their identity in the wilderness. Also such signs are easily overlooked, misunderstood or lost in their natural surroundings. Therefore, even though one attempted to mark trails by using the natural materials at hand, it did not assure such persons from becoming lost. The problem is even more aggravated if a hiker or camper planned an extensive trip into unknown wilderness, as for example, for several days, as the natural signs used for trail marking would tend to soon disappear, wash away or be altered by an animal or subsequent passer by. Thus, the natural materials heretofore utilized to mark a trail, at best, had only limited duration, and did not constitute a positive and lasting means to permanently mark a trail. 
   Hunters, hikers, explorers and participants in other outdoor activities often need or would like to know where they are or where they have been in a forest or other outdoor area. A hunter, for example, would like to be able to find his way back to a choice hunting location. He may want to let another hunter, who is to join him later, know where he is and what path he followed. A hunter may need to leave harvested game or equipment temporarily to obtain help to carry the game or equipment away, in which case, he needs to be able to find his way back to the spot of the kill relatively quickly. 
   Finding one&#39;s way outdoors traditionally is accomplished with the help of distinctive landmarks, such as a particular rock, a stream or an unusual tree. However, this can be very difficult if one is not familiar with the surrounding environment, or distinctive landmarks are lacking. Outdoor location identification is particularly difficult in the night, when natural landmarks are not easily visible due to low ambient light levels or are altered in appearance by shadows. Thus, hunters and outdoor sportsman will often mark their trail as they proceed to or from a particular location. The marked trail can easily be followed to/from the location by the sportsman at a later date or by others who follow. 
   A variety of devices and methods are known for marking trails outdoors. Typically, such methods involve placing permanent or removable marks or monuments on the ground, trees or other objects, or leaving a trail of markers on or in the ground, trees, etc. Reflective trail markers have become popular because they provide an inexpensive, easy method of marking trails and are highly visible at night when a light source is shined on them. Pieces of reflective tape, for example, are used to mark trails by placing the tape on trees or objects, but such tapes are often not easily securely applied and removed. 
   One type of reflective trail marker currently on the market resembles a thumbtack having a head, which is coated with a reflective coating, such as reflective paint. Such a marker can be pressed into a tree&#39;s bark easily with one hand. The ability to place a trail marker with only one hand is an important advantage, with one&#39;s hands usually occupied with other equipment or accessories when participating in outdoor activities. A series of such markers pressed into trees forms an easily visible trail. The reflective markers are made highly visible in the dark from a distance by shining light, e.g., a flashlight, onto them. However, the heads of these reflective markers are substantially flat, or form only a slight convex curvature. Thus, a light source must shine onto the head from a direction nearly perpendicular to the plane of the head for the reflected light to be visible to a person located at the light source. Also, such tacks can be difficult to remove from the trees or other structures in which they are placed. When employed on frequently used trails, such tacks can accumulate over time, by virtue of their being difficult to remove, and become an environmental eyesore or a misleading/distractive nuisance. Ornamental designs for similarly constructed trail markers are illustrated in U.S. Des. Pat. D445,710 to Lewis and U.S. Des. Pat. D357,428 to Lovelace. 
   Another reflective trail marker currently on the market resembles a tack having a cylindrical head, with the pin portion of the tack extending from one end of the cylinder. This type of trail marker is more easily placed in and removed from trees and other structures than the above described “thumbtack-type” marker. A reflective coating, of tape or paint, is placed substantially entirely about the cylindrical head. Such a reflective head reflects source light directly shined onto it from any angle (360° reflection). However, for any particular angle of incident source light, the actual reflective area can be effectively very small. Therefore, the reflective marker&#39;s effective reflective distance is always relatively short. Moreover, since the reflective head reflects source light shined onto it from any angle, a trail formed by such markers can be easily detected by shining a source light in the general area of the trail. This can be a disadvantage in some cases, such as where the person marking the trail (such as a choice hunting or fishing spot) wishes to keep the trail secret, and thus minimize the possibility of others discovering the trail. Reflective trail markers which reflect light in all directions (360° reflection) can also cause confusion in areas which are marked with several trails. A person shining a light into a forest with several trails marked with such (360° reflection) markers may simultaneously see reflections from markers belonging to different trails, making it difficult to discern the desired trail to be followed. 
   U.S. Pat. No. 6,299,379 to Lewis describes a trail marker having a generally “hour-glass” shaped marker head characterized by a central portion which is straddled by opposed end portions. The central portion of the marker head has one or more sidewall surfaces, which are light reflective. The sidewall surfaces of the marker head may be formed of a reflective material, or may be made reflective by applying reflective paint or tape thereto. The central portion of the marker head is formed to define four flat reflective sidewall surfaces at right angles to each other. This shape is characterized as enhancing the reflective surface area of the central portion of the marker head. The top and bottom cap portions of the marker head are non reflective, and extend beyond the sidewalls of the central portion. The non-reflective cap portions are stated to prevent illumination of and reflection from the central portion of the marker head at angles varying substantially from perpendicular to the reflective sidewall surfaces of the central portion along the axis of the central portion. A pin extends from one end of the marker head, to enable attachment of the marker to a support member, such as a tree. 
   The forgoing trail marker approaches, although having potential limited utility, all have shortcomings, in that they inherently reveal themselves to passers by, reflecting light emanating from any artificial or natural (i.e. sun, moon, lightening, etc.) source which happens to be fortuitously positioned with respect to the observer. This problem is particularly acute in environments, such as thickly grown forests, that contain few, if any, naturally occurring reflective surfaces. In such a situation, a reflected light in the distance naturally draws (unwanted) attention. 
   Another class of trail markers art is exemplified by U.S. Pat. No. 3,685,482 to Ryder and U.S. Patent Application Publication No.: 2002/0152948 to Percle. These devices typically employ a flexible, elongated member and means for fastening one end of the member to a fixed object such as a tree branch. Such markers can be brightly colored and tend to move with air currents to draw attention from any direction. Although inexpensive and easily attached, these markers are only visible with sufficient ambient light. Hours of dawn and dusk tend to create deep shadows, which can obscure or hide this type of marker. The use of such markers in a camouflage motif is also known for more clandestine applications. For example, see U.S. Pat. No. 6,712,286 to Baxter et al. 
   U.S. Pat. No. 5,000,111 to Gibson and U.S. Patent Application Publications 2004/0016786 to Banda, 2004/0206294 to Cavanaugh and 2005/0006423 to Kjeldsen each disclose a trail marking device including an elongated roll of brightly colored and/or reflective material which, in application, is carried by the trail blazer, who periodically severs a short length of the material and secures it at a waypoint along his trail. 
   U.S. Pat. No. 5,669,327 to Beebe describes a trail marking kit including a plurality of reusable colored tags which are made of special biodegradable material. Each tag contains means for attachment to a tree limb or the like to visually mark the trail to allow the user to return to his original destination by visually following the markers. The markers are sized for spacing of 100 or more yards there between, depending upon the density of the vegetation. Upon returning from the hike or journey, the user simply dislodges the previously placed markers from their respective fixed locations. After returning to the origin of the hike, the user will have retrieved all of the markers which may be reused at a later date. Alternately, if the used desires to mark a permanent or semi-permanent trail, the markers may be left in place for future hikes depending upon the user&#39;s intent and nature of the terrain. The use of biodegradable material allows the user to disregard markers which are not retrieved or are lost. They will simply biodegrade over time and disappear without any adverse environmental impact. 
   All of the forgoing prior art approaches require the user to pause at each waypoint and to study the terrain in order to locate the next waypoint. Although this may be easy in bright daylight and in open terrain, the onset of darkness and/or heavy undergrowth can make this more difficult. In low light conditions, the user must carry a light source (e.g. flashlight) and continuously scan its beam back and forth in his field of view in order to locate his next waypoint. This can be difficult when also carrying other equipment, a weapon and/or captured game. Furthermore, if the flashlight is inadvertently lost, damaged or its batteries fail, the upcoming trail markings are of little value. Lastly, the need to continuously scan a flashlight beam off into the distance in darkened terrain while walking an unknown trail can distract the attention of the user from upcoming snags, overhanging branches, obstacles and unseen hazards. 
   Electronic based navigation devices have largely supplanted the above-described devices, particularly in regards to vehicle (ground vehicle, boat, aircraft, etc.) related navigation. Satellite based global positioning systems (GPS) are extremely accurate and can be easily employed to pinpoint an object or individual anywhere on earth. Portable, hand-held GPS systems have recently become available which are suitable for hunters, hikers and the like. The major disadvantage of electronic based navigation devices is still size (difficult to fit in a pocket) and power requirements. Extra batteries and/or a power generator are required for extended treks in remote areas. In addition, such equipment tends to be fragile and can easily be damaged by rough handling or the egress of moisture or contaminates. Lastly, cost and complexity of operation can render known electronic based navigation devices prohibitive for many individuals and applications. Even a trained user must regularly divert his attention to the display and mentally calculate the coordinates of the next waypoint. This can be distracting and dangerous when walking in irregular, darkened and unknown terrain. 
   What is needed is an extremely compact and inexpensive trail marking apparatus that is robust, is simple to use (i.e. is “hands free”), has minimal electrical power requirements and can be employed in both clandestine and open trail/location marking modes. 
   SUMMARY OF THE INVENTION 
   An object of this invention is to provide a simple and inexpensive means by which trails through wilderness can be positively and permanently marked, but which employs marking devices, which are unobtrusive and easily camouflaged/concealed from detection by unauthorized passers by. 
   Another object of this invention is to provide a trail marker, which is specifically constructed for automatic, albeit clandestine usage so that it can be observed by authorized users at a substantial and pre-selectable distance and which can be precisely oriented and firmly secured in place. 
   In the preferred embodiment of the invention, a trail marker device is adapted for pre-positioning at a specific trail waypoint or destination and is operative to self-illuminate in response to an actuation signal. The trail marker device comprises a housing, a closure member which cooperates with the housing to define a substantially sealed cavity, a light source, a power supply and a control circuit which is at least partially disposed within the cavity and is operative to selectively electrically interconnect the light source and power supply to effect externally viewable illumination. 
   According to an aspect of the invention, the trail marker device control circuit includes a radio frequency receiver, which is operative to generate the actuation signal in response to receiving an interrogation signal from a remote transmitter. This arrangement has the advantage of effecting the remote illumination of one or more marker devices nearest the transmitter, which is carried by the hiker. 
   According to another aspect of the invention, the trail marker device includes a wake-up circuit and a timer operative to generate or disable the actuation signal at a predetermined time of day and/or for a predetermined time duration. This saves energy and extends the life of the battery within the trail marker device. 
   According to another aspect of the invention, the power supply of the trail marker device includes a photovoltaic device positioned to receive ambient light and to recharge an electrical energy storage device. This arrangement greatly enhances the operating life cycle of the trail marker device. 
   According to another aspect of the invention, the trail marker device includes an optical lens integrally formed with the closure member for simplicity of design and positioned adjacent the light source to focus and project light emitted by the light source within a predetermined viewing sector disposed about a focus axis. This allows light emitted from the trail marker device to be viewed only near a focus axis. 
   According to another aspect of the invention, a light reflector is disposed adjacent the lens and is configured to direct light received from the light source into the viewing sector. Furthermore, the reflector acts to reflect light received from a remote source in the viewing sector back along the viewing sector towards the remote source. This arrangement allows a flashlight carried by the hiker to be used to locate a non-functioning trail marker device. 
   According to another aspect of the invention, a hood is selectively affixable to the housing and positionable to selectively reduce or limit the viewing sector. 
   According to another aspect of the invention, fixation means such as a barbed nail or a screw extends from the trail marker device to enable securing it to a trailside object in a predetermined orientation. Preferably, the fixation means is elongated along an axis substantially concentric with the axis of said viewing sector. This feature allows “aiming” of the viewing sector of the trail marker device as it is being affixed to a trailside object. 
   According to another aspect of the invention, an outer surface of the trail marker device housing defines a tool-receiving surface adjacent to and spaced from the trailside object for receiving a pry-type removal tool. This simplifies the process of removing the trail marker device from the trailside object. 
   According to another aspect of the invention, a translucent light filter overlays the light source to effect the emission of substantially monochromatic light, preferably in the infrared, visible light and/or ultraviolet frequency ranges. 
   According to yet another aspect of the invention, a remotely actuated trail marker apparatus comprises a transmitter unit which is adapted to be carried by a user and operates to selectively broadcast an interrogation signal throughout a predetermined range. The trail marker apparatus also comprises one or more receiver units, each adapted for positioning at specific trail waypoints or a destination and operative to generate a user sensible reply signal in response to receiving the interrogation signal. 
   According to still another aspect of the invention, the interrogation signal is digitally encoded to effect illumination of a predetermined limited subset of receiver units within said range. This allows the transmitter to discriminate among certain trail marker devices. 
   According to still yet another aspect of the invention, the transmitter unit comprises an output power selection circuit, which operates to selectively broadcast interrogation signals having substantially different ranges. This allows the user to select a broadcast range to illuminate one or a plurality of trail marker devices. 
   These and other features and advantages of this invention will become apparent upon reading the following specification, which, along with the drawings, describes preferred and alternative embodiments of the invention in detail. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
       FIG. 1 , is a perspective illustration of a portion of a forest trail as marked with an illuminated trail marker apparatus in accordance with the present invention; 
       FIG. 2 , is an overhead map of a wilderness trail defined by a plurality of pre-positioned inventive trail marker receiver units; 
       FIG. 3 , is perspective plan view of the preferred embodiment of the trail marker receiver unit; 
       FIG. 4 , is a cross-sectional view, taken on line  4 - 4  of  FIG. 3 , on an enlarged scale; 
       FIG. 5 , is a front plan view of the preferred embodiment of the trail marker transmitter unit; 
       FIG. 6 , is a perspective, cross-section view of a supplemental trail marker receiver unit attachment clip, on an enlarged scale; 
       FIG. 7 , is a broken, cross-sectional view of a portion of the trail marker receiver unit of  FIGS. 3 and 4 , on an enlarged scale; 
       FIG. 8 , is a cross-sectional view of an alternative embodiment of the trail marker receiver unit; 
       FIG. 9 , is a perspective view of an accessory message panel for use with a trail marker receiver unit to convey information to a searcher, rescuer or subsequent passer by; 
       FIG. 10 , is a schematic illustration of the trail marker transmitter and receiver units of a second alternative embodiment of the invention; 
       FIG. 11 , is a perspective view of the transmitter portion of the second alternative embodiment of the invention illustrated schematically in  FIG. 10 ; 
       FIG. 12 , is a cross-sectional view of the receiver-trail marker portion of the second alternative embodiment of the invention which can be employed with the transmitter unit of  FIG. 11 ; and 
       FIG. 13 , is a plan view in partial cross-section of a hand-held tool for precisely positioning, mounting and removing trail marker receiver units at predetermined trail waypoints. 
   

   Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to illustrate and explain the present invention. The exemplification set forth herein illustrates an embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present invention is primarily intended for hunters, fishermen and other sportsmen who have identified good hunting/fishing cites in the woods/wilderness to which they wish to return, and will be described in that context. Because sportsmen frequently walk through the woods during hours of dawn/dusk, or even in total darkness, the present invention provides a simple to use, hands-free device which provides a self-illuminating succession of waypoint markers defining a preferred trail. After a given time, the markers self-extinguish to enhance battery life. Only an appropriately coded transmitter carried by the user will activate the waypoint markers, ensuring secrecy and effectively hiding the trail from non-authorized users. Although described in the context of its preferred sporting usage, the present invention can be applied for many applications such as covert military and police missions, rescue/recovery of lost or injured parties, survival equipment packages and the like. Accordingly, the following description is deemed illustrative and is not to be construed as limiting. 
   Referring to  FIG. 1 , the preferred embodiment of the invention comprises a trail marker apparatus or system  10  including a transmitter unit  12  ( FIG. 5 ) and at least one trail marker device/receiver unit  14  ( FIG. 3 ). The transmitter unit  12  contains a battery powered, digitally encoded radio frequency (RF) transmitter circuit. In application, the transmitter unit  12  is carried by the hunter by a lanyard or other suitable means and, when activated, periodically broadcasts an interrogation signal. A plurality of trail marker units  14  are pre-positioned at fixed waypoints along the trail. Successive marker units  14  are spaced to be well within the nominal effective range of the transmitter unit  12 . Preferably at least several of the closest trail marker units  14 , in both directions, are easily within the range of the transmitter unit  12 . 
   Still referring to  FIG. 1 , the operation of the present invention will be described. It is contemplated that the trail marker system  10  would be provided with one or two transmitter units  12  and a relatively large number (perhaps 30-50) trail marker devices  14 . Additional/replacement tree marker devices  14  can also be provided separately. When a desirable location is identified in a remote area, such as a tree  16 A suitable for a hunting tree stand  18 , the user will attach a first trail marker device  14 A to tree  16 A in a position such that it will be viewable from a distance in the general direction of the proposed trail and oriented such that its longitudinal axis A-A ( FIG. 4 ) extends in that direction. The trail marker device  14 A is then activated by completing an electrical circuit, as will be described in greater detail herein below. Next, the user would walk for a distance and identify a first waypoint, such as a tree  16 B. After confirming that trail marker device  14 A is along a direct line of sight to tree  16 B, a second trail marker device  14 B is installed on tree  16 B and energized. Thereafter, the process is repeated whereby trail marker devices  14 C- 14 E are installed on respective trees  16 C- 16 E. Thus, a “marked” trail is established by the pre-positioning of a series of trail marker devices  14 A- 14 E, which are attached to a series of trees  16 A- 16 E, respectively. 
   Although  FIG. 1  illustrates the placement of the trail marker devices  14 A- 14 E in highly visible locations, in practice, they would be secreted within foliage, branches and the like, while maintaining their direct line of sight orientation with at least both immediately adjacent waypoints. This results in their being very difficult to discern unless in the illuminated state. Furthermore, although  FIG. 1  suggests placement of the trail marker devices  14 A- 14 E such that they are viewable only to a user who is moving along the trail in a direction toward the tree stand  18 , in practice, they may be placed so as to be visible while walking towards and away from the tree stand  18 . 
   Referring to  FIG. 2 , an overhead view or map perspective of a marked trail  20  extending from a parked user vehicle  22  on the side of a well defined road  24  to a camouflaged hunting blind  26 , is illustrated. Trail  20  is defined by a series of fourteen (14) trail marker devices  28 A- 28 N extending from a start point  30  at or near the vehicle  22  to an end point  32  at or near the hunting blind  26 . In laying out the trail  20 , the user sought to avoid natural obstacles such as a river  34 , swamp  36  and extremely heavy vegetation  38 , as well as man-made impediments such as private/posted property  40 . In addition, the trail  20  takes advantage of natural features such as rocks  42  defining a suitable river ford, and a dead-fall (tree)  44  across a narrow portion of the swamp  36 . 
   Beginning before sunrise, the user can drive along the road  24  with a transmitter unit  46  already energized. As he (in his car  22 ) approaches the start point  30  of the trail  20 , trail marker device  28 A will become illuminated as he approaches, providing an initial orientation. After parking the car  22 , he approaches trail marker device  28 A and looks for device  28 B, which is now also illuminated. He then walks directly toward marker  28 B. As he approaches marker  28 B, marker  28 C has become illuminated. Thus, as he approaches marker  28 B, he changes his direction to head directly for marker  28 C. As he approaches marker  28 C, marker  28 D has become illuminated. Markers  28 C and  28 D are preferably placed strategically to highlight the beginning and end of the hazard (rocks  42 /stream 34 ). 
   After traversing the stream  34 , the user continues to sequentially locate and walk toward trail marker devices  28 E,  28 F,  28 G and  28 H in succession. As the user  48  approaches marker  28 H, both markers  281  and  28 J become illuminated nearly simultaneously to highlight a particularly dangerous hazard, the dead-fall  44 . Up to this point the user  48  has the transmitter  46  set at a low output power setting, wherein the transmitter has an effective range designated by arrow R 1  and typically illuminates only one marker at a time, to minimize the possibility of being observed. If he so chooses, the user  48  can select a higher output power setting, giving the transmitter  46  an extended effective range designated by arrow R 2 . Insodoing, he will also illuminate markers  28 K and  28 L on the far side of the dead-fall  44  to assist in its traversal. 
   As the user  48  approaches marker  28 K, he will reduce the power of the transmitter, and then continue along trail  20  by sequentially locating and then walking toward markers  28 L,  28 M and finally  28 N, having arrived at the trail end point  32  at the hunting blind  26 . Thereafter, he de-energizes the transmitter to immerse himself in darkness and begin hunting. As will be described in detail herein below, each of the trail marker devices  28  will be de-illuminated as soon as they fall outside of the effective range of the transmitter  46 , or alternatively, will turn themselves off after a predetermined period of time. At the end of the hunting day, the user  48  will reverse the above described process, traversing the trail  20  from the end point  32  to the vehicle  22  near the start point  30 . An extra trail marker device  28 P can also be mounted or temporarily placed in an open or visible location on the vehicle  22  to further assist its location by the user  48 . 
   Referring to  FIGS. 3 and 4 , a preferred embodiment of an illustrative trail marker device  50  is illustrated. Each trail marker device  50  is adapted for pre-positioning at a specific trail waypoint, target or destination and is operative to self-illuminate in response to an actuation signal, as will be described herein below. The trail marker device  50  is designed to be relatively low cost whereby the user will not hesitate to employ them in adequate numbers (i.e., with minimized spacing there between) to maximize trail delineation and provide a degree of redundancy between adjacent devices  50 , and will not be unduly concerned if a limited number of devices  50  malfunction or are lost. 
   Trail marker device  50  includes a housing  52  and a closure member  54 , which cooperates with the housing  52 , in assembly, to define a substantially closed cavity  56 . Housing  52  preferably is formed of stamped mild steel, or other suitable material such as plastic, in the shape of a cup, having a bottom  58  integrally formed with a sidewall  60  which radially transitions step-wise along its longitudinal axis A-A from a maximum diameter portion  62  adjacent the open end  64  of the housing  52 , to an intermediate diameter portion  66 , to a minimum diameter portion  68  adjacent the bottom  58 . The closure member  54  is preferably formed of optically clear plastic or other suitable material and is slip fit within the maximum diameter portion  62  of sidewall  60  and nestingly engages the radially extending portion  70  of the sidewall  60  transitioning from the maximum diameter portion  62  to the intermediate diameter portion  66 . A resilient annular seal  72 , formed of rubber or other suitable material, provides a hermetic seal between the inner surface  74  of closure member  54  and radially extending portion  70  of sidewall  60 . 
   A generally annular printed circuit board (PCB)  76  is slip fit within the intermediate diameter portion  66  of the sidewall  60  and nestingly engages the radially extending portion  78  of the sidewall  60  transitioning from the intermediate diameter portion  66  to the minimum diameter portion  68  via an adhesive ring seal  77 . The PCB  76  is preferably constructed of monolithic or composite plastic material, ceramic or other suitable electrically insulating material and serves to carry an array of suitable integrated circuits and discrete electrical components making up a control circuit  80  and a light source  82 , such as a light emitting diode (LED). The PCB  76  also carries conductive circuit traces (not illustrated) on one or both surfaces thereof to electrically interconnect the electrical components to complete the control circuit  80  and to establish an electrical ground path from the circuit to the (electrically conductive) housing  52 . A resilient electrical power input contact  84  extends below the PCB  76 . 
   A source of electrical power such as a battery  86  is slip fit within the minimum diameter portion  68  of the sidewall  60  and nestingly engages the inner surface of the bottom  58  of the housing  52 . The outer case (negative terminal) of the battery  86  is grounded to the housing  52  and the positive terminal  88  extends upwardly to engage contact  84  to provide electrical power to the control circuit  80 . Many types of battery (liquid/dry cell, alkaline, lithium, silver oxide, cadmium, titanium, and the like) can be satisfactorily employed. As will be apparent herein after, other sources of electrical energy, such as a charged capacitor, a rotating induction machine or the like could be used in conjunction with or in place of a battery. This can be important in circumstances where the trail marker device  50  has been in long term storage/use and a fresh, charged battery  86  is unavailable. 
   Prior to usage of the trail marker device  50 , the control circuit  80  can be de-energized by inclusion of an electrically insulating material such as a Mylar strip  90  to separate (and electrically isolate) the positive terminal  88  of the battery  86  and the electrical contact  84 . In the preferred embodiment illustrated in  FIGS. 3 and 4 , the Mylar strip  90  is elongated to extend outwardly through a small opening  92  in housing  52  and terminate in an enlarged end portion  94  suitable for manual gripping and removal. The enlarged end portion  94  of the Mylar strip  90  preferably has instructional indicia  96  imprinted thereon. Accordingly, with the Mylar strip  90  in place, the trail marker device  50  can be stored for long periods of time without risk of the battery  86  becoming discharged. When the trail marker device  50  is to be activated before being mounted to define a trail, the Mylar strip  90  is simply removed, as indicated by arrow  97  ( FIG. 4 ) and discarded or preserved for reuse when the marker is de-activated. The annular seal  77  is sufficiently resilient to self-seal the opening  92  after removal of the Mylar strip  90 . 
   Fixation means, such as a metal spike  98 , includes a generally flat head portion  100  affixed, such as by welding, to the outer surface of the bottom  58  of the housing  52  of the trail marker device  50  and rigid elongated member  102  depending outwardly there from. The elongated member  102  is preferably pointed to facilitate its impaling trees, fence posts, wooden structures, and the like with relative ease during the mounting process. Barbs  104  are formed along elongated member  102  to prevent its unintended disengagement over time due to ambient temperature cycles, relaxation of the host wood fibers/grain, contact with moving foliage or wildlife and the like. 
   Referring to  FIG. 7 , closure member  54  comprises an optically clear structural lens portion  106 , an intermediate annular light scattering reflector portion  108 , and an outer translucent filter portion  110 . Reflector portion  108  has a mirrored second surface  112  adhered to the top surface  114  of lens portion  106 . Reflector portion  108  has a geometrically scribed outer or first surface  116 , preferably a series of concentric saw-tooth circles, providing a large number of reflective facets which tend to reflect received ambient and remotely projected light as well as light generated by the LED  82  outwardly in a wide conical field defined by lines  118  (refer  FIG. 4 ) symmetrically about axis A-A. 
   Filter portion  110  can be made of Mylar or other suitable material which self-adheres to first surface  116  of reflector portion  108  whereby it could be easily removed and replaced by another filter portion which passes light of a different wave length (color) or, alternatively, eliminated all together. 
   As best viewed in  FIGS. 3 and 4 , the center of lens portion  106  has an integral convex lens  120  extending outwardly concentrically with axis A-A. LED  82  is located in a recess  122  formed in the inner surface  74  of lens portion  106 . Thus, the lens  120  cooperates with the LED  82  body to establish a composite lens, which can be easily modified to vary its effective focal length and other operating characteristics. Lens  120  extends through a central opening in reflector portion  108 . Lens  120  can be overlaid by filter portion  110  whereby all reflected/emitted light from the trail marker device  50  is a single color or, alternatively, lens  120  can also extend through a concentric central opening (not illustrated) in filter portion  110  to effect emitted light of a first color and reflected light of a distinctly different color. Furthermore, reflective portion  108  can be integrally molded with lens portion  106  with its first surface  116  being reflective. Also, filter portion  110  can be a permanent coating or integrally formed as a color pigment of the material forming lens portion  106  and/or reflector portion  108 . 
   Referring to  FIG. 7 , a tool receiving recess  124  is formed in preferably three circumferentially equally spaced locations on the outer periphery of closure member  54 . A localized portion of the maximum diameter portion  62  of housing  52  adjacent each tool receiving recess  124  is deformed radially inwardly to form an engagement tab  126  which extends within tool receiving recess  124  to resiliently retain closure member  54  in its illustrated position. Should the battery  86  require replacement the engagement tab(s)  126  are deformed radially outwardly by a screwdriver, knife blade or other suitable elongated tool. In usage, the tool is inserted within recess  124  and levered outwardly against the tab  126 . The closure member  54  and PCB  76  are then removed to provide access to the battery  86 . Once the battery  86  is replaced and the PCB  76  and closure member  54  returned to their illustrated positions, the tabs  126  are bent radially inwardly to their illustrated original positions. 
   Referring to  FIG. 5 , a preferred embodiment of a transmitter unit  128  for use with the trail marker device  50  of  FIGS. 3 ,  4  and  7  comprises a housing assembly  130  including a keypad portion  132 , an identification portion  134  and a mounting portion  136 . The housing assembly  130  is preferably two substantially mirror image housing halves constructed of injection molded plastic, which snap together to form a substantially hermetically sealed cavity containing a battery, a radio frequency transmitter and a control circuit, which will be described in greater detail herein below. 
   The mounting portion  136  of transmitter unit  128  defines a through hole  138  for receiving a lanyard or, alternatively, a split retaining ring  140  for use as a key fob or secured attachment to the user while he approaches/traverses a marked trail  20  ( FIG. 2 ). Overall, the transmitter unit  128  is generally similar in size to a typical automotive remote entry system transmitter. The keypad portion  132  provides a user interface for programming and controlling operation of the transmitter unit  128 . The keypad portion  132  preferably includes function specific switches, indicators and devices such as an “on-off” (i.e. push-push) switch  142 , a “power on” indicator light  144 , an array of digital code program set/dual inline package (DIP) switches  146  and a “code set” (i.e. push) switch  148 , along with associated function indicia. As will become apparent from a reading of the description of an alternative embodiment of the invention herein below, controls/readouts for additional functions (such as continuous transmission mode or periodic transmission mode) can be added. The identification portion  134  of the transmitter unit  128  can include instructional or promotional indicia  146 . 
   Referring to  FIG. 6 , a mounting clip  148  can be applied to assist in the mounting of the trail marker device  50  ( FIGS. 3 &amp; 4 ) to a mounting structure providing only thin-sectioned material, such as fabric, to support the device  50 . Examples could be the canvas wall of a hunting blind or shelter, or an article of clothing (either fixed to another object or worn by a guide/hunter or the like). The mounting clip  148  can be applied as a backer when the elongated member  102  of a mounting spike  98  penetrates the mounting material and extends outwardly beyond its far side. 
   The mounting clip  148  is generally u-shaped, and includes a base portion  150  and opposed side portions  152  and  154  cantilevered there from. A pair of opposed lanced tabs  156  and  158  are formed in the center of the base portion and extend angularly there from in the general direction of extension of the side portions  152  and  154 . The lanced tabs  156  and  158  cooperate to define a through passage  160  dimensioned to establish an interference fit with the elongated member  102  of a mounting spike  98 . 
   Referring to  FIG. 8 , a flexible hood  162  can be employed with the trail marker device  50  to controllably limit the effective operational viewing sector from a maximum field depicted by lines  164 , to a reduced field depicted by lines  166 . The viewing sector is disposed symmetrically about axis A-A, and is defined as the sector of space facing the closure member  54  of an operational trail marker device  50  within which the user can observe light emitted there from when no intermediate obstacles are present. The hood  162  would be employed when the trail marker system  10  is employed for clandestine purposes, or it is desired to define a precise line of approach to a specific trail marker device  50 . 
   The hood  162  is preferably constructed of relatively soft, pliable vinyl, rubber, or other suitable material. The hood  162  is generally shaped as an open-ended cylinder with a tapered first end  168  and a stepped reduced radius second end  170 . The first end  168  defines a restricted opening  172 , which defines the size of the viewing sector based upon its effective diameter and axial spacing from the LED. The second end is configured for attachment to the trail marker device  50 . The second end  170  of the hood  162  defines a step portion  174 , which resiliently embraces the outer peripheral surface of the maximum diameter portion  62  and the radially extending portion  70  of the housing  52  of the trail marker device  50 . As illustrated, the hood  162  has an outer surface  176  configured/colored in a camouflage motif to render it inconspicuous to an unknowing passerby and an inner surface  178  which is brightly colored (such as fluorescent or “hunter&#39;s orange”) to maximize its attention attracting quality. Depending upon the user&#39;s intentions, the hood  162  can be easily removed from the trail marker device  50 , inverted, and reapplied, rendering it highly visible. 
   As an aid in setting up a hooded trail marker device  50  so as to have a specific predetermined viewing sector size, calibration marks  180 ,  182  and  184  are provided on the outer surface  176  of the hood  162  which, when aligned with the opening  64  ( FIG. 4 ) of the housing  52  of the trail marker device  50 , provide viewing sectors with 60°, 90° and 120° ranges, respectively. The forgoing is to be viewed as an example only. 
   In application, the elongated member  102  of the mounting spike  98  would be pushed through its host fabric until the head portion  100  abuts the front surface of the fabric. The mounting clip  148  is there after applied from the rear with the elongated member  102  passing through the passageway  160  and the side portions  154  and  156  projecting rearwardly. The mounting clip  148  is displaced fully along the elongated member  102  until the leading surface of the base portion  150  abuts the rear surface of the fabric. The mounting clip  148  is removed by momentarily resiliently manually deflecting the free ends of the side portions  152  and  154  away from one another (as well as the elongated member  102 ). This releases the engagement of the sharp free ends of the lanced tabs from the elongated member  102 . The mounting clip  148  can then be simply removed from the elongated member  102 . The mounting clip  148  can be constructed of spring steel, injection molded plastic or other suitable material. 
   Referring to  FIG. 9 , a message panel/form  186  which can be used in conjunction with the trail marker system  10  is illustrated. Message form  186  is preferably constructed of opaque, lightweight material such as Mylar which is water resistant and can be rolled up for convenient, compact storage when in the field. The form  186  can be colored with either a camouflaged or brightly colored motif, depending upon its intended application. The form  186  can be color reversible, rendering it useful for both applications. The form preferably has certain instructional indicia  188  imprinted thereon and has a surface texture suitable for being used with a common writing instrument such as a pencil  190  or water resistant permanent marker. 
   The form  186  has one end folded over to form a hermetically sealed pocket  192  for receiving and storing the pencil  190 , until its usage is required. Perforations  193  are provided in the Mylar material near one end of the pocket  192  as an aid to opening the pocket  192  for removal of the pencil  190 . The form  186  also defines a fastening tab  194  adapted for securing it to an object in a fixed orientation adjacent to a trail marker device  50  by passing the elongated member  102  through a pre-punched hole  196  in fastening tab  194 . 
   Referring to  FIG. 10 , a functional schematic diagram of a second alternative embodiment of the invention, including a transmitter unit  198  and a receiver unit  200  is illustrated. As in the case of the preferred embodiment of the invention described in connection with  FIGS. 4 and 5 , the transmitter unit  198  is designed to be carried with the user and the receiver unit or trail marking device  200  is designed for pre-placement at a waypoint along a marked trail. 
   The transmitter unit  198  includes a control circuit  202  including a radio frequency (RF) transmitter  204 , which either continuously or periodically broadcasts an RF interrogation signal  206  via a transmitting antenna  208 . A power supply  210 , such as a battery, provides power to the transmitter unit  198 . A timer circuit  212  provides timing pulses to effect periodic broadcast of RF signals  206  when in a certain operating mode. 
   The transmitter unit  198  also includes operator interface circuits  214  including a power on-power off switch  216 , a power level set switch  218  which controls the power level (and thus range) of the RF signal  206 , a digital code set circuit  220  which, with the control circuit  202 , incorporates a digital identification code within the RF signal  206 , and a digital code mode set circuit  222 , which causes the RF transmitter to broadcast RF signals either continuously on in accordance with a timed period. 
   The receiver unit  200  includes a control circuit  224  including a RF receiver  226 , which receives and decodes the RF interrogation signal  206  through a receiving antenna  228 . A power supply  230 , such as a battery or a battery in combination with a storage capacitor, provides power to the receiver unit  200 . A photovoltaic device  232  provides a continuous charge current to the power supply capacitor in the presence of sufficient ambient light and provides an input signal to the control circuit  224  which can be used to control the intensity of a light source  234 , such as a LED, as a function of ambient lighting conditions. A timer circuit  236  is provided to trigger a wake-up circuit  238 , which, in turn, energizes the power supply  230  and the control circuit  224 . 
   The receiver  200  also includes operator interface circuits  240  including a power on switch  242  and a digital code set circuit  244 , which mimics the code established by the digital code set circuit  222  of the transmitter circuit  198 . The digital encoding-decoding feature enhances operational security inasmuch as a user must have knowledge of the code settings. Preferably, the code set circuits  220  and  244  include identical DIP switches which can be identically preset by the user. 
   The rapid recent growth of microelectronic device technology, and particularly, the widespread usage of digital electronic systems provide one of ordinary skill in the art with many options in practicing the present invention. By way of example, systems that might be of interest in practicing the present invention are U.S. Pat. No. 5,699,065 to Murray, entitled “Remote Control Transmitter and Method of Operation”, U.S. Pat. No. 5,229,649 to Nielson et al., entitled “Light-Energized Electronics Energy Management System” and U.S. Pat. No. 6,593,845 B1 to Friedman et al., entitled “Active RF Tag with Wake-Up Circuit to Prolong Battery Life”. All three (U.S. Pat. No. 5,699,065, U.S. Pat. No. 5,229,649 and U.S. Pat. No. 6,593,845 B1) patents are hereby incorporated within this application by reference. 
   Referring to  FIG. 11 , an exemplary configuration of the transmitter unit  198  from  FIG. 10  is illustrated. Transmitter unit  198  includes a hermetically sealed housing assembly  246  formed of injection-molded plastic or other suitable material. The housing assembly  246  is generally rectangular in shape and is elongated and dimensioned to facilitate being held in the palm of the user&#39;s hand. The housing assembly  246  has a first end  248  from which an integral retention loop  250  depends. Retention loop  250  defines a through passage  252  which receives a lanyard  254  which, in use, would be worn around the user&#39;s neck for hands-free operation. 
   The housing assembly  246  has a second end  256  opposite the first end  248  from which extends an integral pry bar tool  258  used for removing trail marker devices from their mounted position on a tree or the like. The pry bar tool  258  is of robust design, having a nominal thickness designated “T” which is slightly less than the axial dimension of the minimum diameter portion  68  of the housing  52  of the trail marker device  50  illustrated in  FIGS. 3 and 4 . Tool  258  is employed by inserting a leading edge  260  or side edge  262  intermediate the radially extending portion  78  of the trail marker device  50  and the adjacent surface of the tree trunk and then applying a prying motion to the housing assembly  246  to draw the elongated member  102  from the tree trunk. 
   The pry bar tool  258  has a wrench tool  264  integrally formed therein. The wrench  264  is defined by two parallel surfaces  266  and  268  spaced by a dimension “W” which corresponds with a characteristic flat-to-flat dimension of a hexagonal feature on an alternative design trail marker device/receiver unit  200  as will be described herein below. 
   All user settable controls of the operator interface circuits  214  are disposed on the upper surface  270  of the housing assembly  246 . A power on-off switch  272 , a range select switch  274  and a broadcast mode select switch  276 , as well as a digital code select switch array  278  are carried on the upper surface  270  of housing assembly  246 . A compass  280  and a laser pointer  282  are integrated within housing assembly  246 . A laser on-off switch  284  is carried on the upper surface  270  of housing assembly  246 . The laser pointer  282  and compass  280  are extremely valuable additions to the trail marking system, particularly in meets and bounds plotting or laying out a trail as it is being marked. 
   Although the housing assembly  246  is preferably of minimal size and weight for use in the field, its utility is enhanced by the inclusion of a first closable compartment  286  for holding an adequate supply of trail marker devices and a second closable compartment  288  for holding extra batteries and mounting clips. Multiple storage nitches  290  for a supply of message forms  186  ( FIG. 9 ) are formed in a side surface  292 . When the trail marker system is employed as survival gear, matches, a reflective signaling device, first aid essentials and the like could also be stored within the housing assembly  246 . 
   Referring to  FIG. 12 , an alternative embodiment of a trail marker device  294  comprising the receiver unit  200  ( FIG. 10 ) is illustrated for usage with the transmitter unit  198  of  FIG. 11 . The trail marker device  294  is similar in many respects to trail marker device  50  described in connection with  FIGS. 3 and 4  herein above. Thus, for the sake of brevity, only the differences will be highlighted here. 
   The trail marker device  294  includes a housing  296  and a closure member  298 , which cooperates with the housing  296 , in assembly, to define a substantially closed cavity  299 . Housing  296  is formed in the shape of a cup, having a bottom  300  integrally formed with a sidewall  302  which radially transitions step-wise along its longitudinal axis B-B from a maximum diameter portion  304  adjacent the open end  306  of the housing  296 , to an to a minimum diameter portion  310  adjacent the bottom  300 . The closure member  298  is preferably formed of optically clear plastic or other suitable material and is removably attached to the housing  296  by cooperating thread forms  312  and a resilient gasket  314  to form a hermetic seal. 
   A generally annular PCB  316  is slip fit within the maximum diameter portion  304  of the sidewall  302  and nestingly engages the radially extending portion  318  of the sidewall transitioning from the maximum diameter portion  304  to the minimum diameter portion  310  via an adhesive seal ring  320 . The PCB  316  serves to carry an array of suitable integrated circuits and discrete electrical components making up the receiver control circuit  200 . The PCB  316  also carries conductive circuit traces (not illustrated) on one or both surfaces thereof to electrically interconnect the electrical components to complete the receiver control circuit  200  and to establish an electrical ground path from the circuit  200  to the (electrically conductive) housing  296 . A resilient electrical power input contact  322  extends below the PCB  316 . 
   A second PCB  324  supports a light source  326  such as a LED as well as additional circuit components  327 . PCB  324  is affixed to the closure member  298  by a system of integral tabs  328  and a resilient spacer  330 . Flexible conductors  332  interconnect the two PCBs  316  and  324 . 
   A source of electrical power such as several serially arranged batteries  334  are slip fit within an insulating sleeve  336  disposed within the minimum diameter portion  310  of the sidewall  302 . The negative terminal or case of the bottom battery  334  nestingly engages the inner surface of the bottom  300  of the housing  296  and establishes electrical contact therewith. As illustrated, the three batteries  334  are series connected, with the positive terminal of the top battery  334  electrically in circuit with the electrical contact  322 . 
   An on-off (push-push) switch  338  and a programmable DIP switch array  340  are mounted on PCB  316 . Switch  338  is part of the power on circuit  242  ( FIG. 10 ) and includes a plunger type actuator  342  extending through a sealed bushing  344  within the sidewall  302  of housing  296 . The receiver unit  200  is electrically powered by pushing and releasing the plunger  342  as indicated by arrow  346 . DIP switch  340  is part of the digital code set circuit  244  ( FIG. 10 ) and is accessed and programmed by removing the closure member  298  and manually presetting the individual switches to correspond to those of switch assembly  278  of the transmitter unit  198  ( FIG. 11 ). 
   Closure member  298  is generally shaped as an inverted cup, including a top portion  348  and a circumferential skirt portion  350  integrally formed therewith from optically clear plastic. The lowermost or open end of skirt portion is affixed to the open end  306  of housing  296  via thread forms  312 . An integral convex lens  352  is centrally formed on the outer surface of the top portion  348  of the closure member  298 . A concave recess  354  is formed in the inner surface of the top portion  348  of closure member  298  positioned concentrically with lens  352  and axis B-B. LED  326  is disposed within recess  354 . A light scattering reflector portion  356  is carried on the outer surface of the top portion  348  of the closure member  298  concentrically with lens  352 . 
   The point of transition between the top portion  348  and skirt portion  350  of closure member  298  is thickened about its entire circumference to form a cylindrical lens  358 . As depicted by lines  359  and  361 , lens  358  is configured to omni-directionally focus ambient light upon a photovoltaic device  360  centrally located on PCB  316  within cavity  299 . With this arrangement, sunlight received from any (360°) direction can be focused upon the photovoltaic device  360  for maintaining the electrical charge in a capacitor  362  or the batteries  334 . 
   Fixation means  362 , such as a screw shaped structure including a hexagonally shaped head portion  364 , is affixed, such as by welding, to the outer surface of the bottom  300 . A threaded elongated member  366  depends axially downwardly from the head portion  364 . The elongated member  366  is preferably pointed and adapted to be screwed into trees, fence posts, wooden structures, and the like with relative ease during the mounting process. If necessary, the wrench  264  ( FIG. 11 ) associated with the transmitter unit  198  can be employed to attach or remove the trail marker device  294  to its waypoint attachment structure. 
   The trail marker device  294  operates substantially in the same manner as the trail marker device  50  described herein above, with the principle differences that the trail marker device  294  can more easily/repeatedly be turned on and off, has a greater reserve of electrical energy by virtue of its multiple batteries, storage capacitor  363 , and, most importantly, the ability to recharge itself during hours of sunlight. As a result, the trail marker device can remain in the field in an active state almost indefinitely. 
   Referring to  FIG. 13 , a hand tool  368 , useful for installing and removing trail marker devices  50  is illustrated. The open end  64  of the housing  52  defines a tool receiving abutment surface  65  ( FIGS. 3 and 7 ). Hand tool  368  has a generally inverted cup shape including a top portion  370  and a peripheral skirt portion  372  formed integrally from relatively heavy gauge cast or stamped steel. The hand tool is configured and dimensioned to nestingly receive a trail marker device  50  (in phantom) within a cavity formed therein. Top portion  370  defines an upstanding central portion  376  forming a central pocket  378  within the cavity  374 . The upper surface of the upstanding portion  376  of the top portion  370  forms a striking surface  380 . Two or more circumferentially opposed latches  382  and  383  are pivotally affixed to the outer surface of the hand tool  368  via hinges  384 . Each latch  382  and  283  forms an upwardly facing abutment surface  386 . Latch  382  is illustrated in an engaged position and latch  383  is illustrated in a released position. 
   The hand tool  368  operates to allow a trail marking device  50  to be affixed to a tree or other suitable object at a waypoint by a single blow from a hammer, rock, or other suitable device indicated by arrow  388 . The hand tool is employed to install a trail marking device  50  by first nestingly positioning the trail marking device  50  within the cavity until the tool abutment surface  65  Contacts the inner surface  390  about the entire circumference of the housing  52 . This allows the distribution of the striking force about the entire circumference of the housing  52  of the trail marker device  50 . The pocket provides clearance is maintained from the relatively fragile closure member/lens assembly  54 . Furthermore, the tool  368  aligns the striking surface  380  normally to and concentric with the axis C-C, ensuring that the force of the blow is directed axially through the elongated member  102  into the attachment object (tree). 
   The hand tool  368  can be employed to remove a trail marker device  50  from an installed position by first placing the tool in the illustrated position vis-à-vis the trail marker device  50  and then folding the latches from the release position to the engaged position. Finally, a lever device (not illustrated) is inserted between the lowermost surface  392  and the object to which the trail marker device is mounted. A prying motion of the lever device will withdraw the elongated member  102  from the object. This allows the application of relatively high force loads without damaging the relatively fragile components of the trail marker device. 
   It is to be understood that the invention has been described with reference to specific embodiments and variations to provide the features and advantages previously described and that the embodiments are susceptible of modification as will be apparent to those skilled in the art. 
   Furthermore, it is contemplated that many alternative, common inexpensive materials can be employed to construct the basis constituent components. Accordingly, the forgoing is not to be construed in a limiting sense. 
   The invention has been described in an illustrative manner, and it is to be understood that the terminology, which has been used is intended to be in the nature of words of description rather than of limitation. 
   Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, it is contemplated that a transmitter unit, such as that identified by reference numeral  198  in  FIG. 11  could be integrated with a flashlight. The flashlight could emit light in either the visible frequency spectrum or in the non-visible frequency spectrum (ex. infrared, ultraviolet, and the like). The flashlight would preferably be oriented to emit light through the second end  256  of the housing assembly  246 . The function switch  284  could be reconfigured to control both the flashlight and the laser pointer  282 . Furthermore, the hand tool  368  described in connection with  FIG. 13  would preferably also be integrated into the housing assembly  246  of  FIG. 11  to enhance its overall utilitarian value. It is, therefore, to be understood that within the scope of the appended claims, wherein reference numerals are merely for illustrative purposes and convenience and are not in any way limiting, the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the Doctrine of Equivalents, may be practiced otherwise than is specifically described.