Abstract:
A device fixes an object to a tree. The device includes an elongate body, one end of which is adapted for attachment to a tree. An object is slidably mounted on the elongate body. The device also includes a device for biasing the object towards the end of the body adapted for attachment to the tree. In use, pressure resulting from growth of the tree is transmitted to the object and pushes it along the elongate body against the bias and away from the tree.

Description:
BACKGROUND OF THE INVENTION 
   (1) Field of the Invention 
   The present invention relates to fixing an object to a tree. 
   (2) Description of Related Art 
   Fixing objects to trees can cause damage. This is particularly the case when several fixtures have to be made, for example cable clips for when a lightning protection system. Conventionally, plastic or metal nails or screws are used for this purpose. However, as the tree grows these and the cable clips can become fully embedded in the tree and cause disfigurement. This is particularly a problem for rare or “veteran” trees which are of scientific or historical value. 
   BRIEF SUMMARY OF THE INVENTION 
   According to one aspect of the present invention there is provided a device for fixing an object to a tree, the device including: 
   an elongate body, one end of which is adapted for attachment to a tree, in use an object being slidably mounted on the elongate body, and 
   a device for biasing an object slidably mounted on the elongate body towards the end of the body adapted for attachment to the tree, 
   in use, pressure resulting from growth of the tree being transmitted to the object and pushing it along the elongate body against the bias and away from the tree. 
   The inventor has found that using such a device that means that it is possible to reduce the risk of the object becoming embedded within the tree. Although parts of the device such as the elongate body may become embedded, these tend to be relatively small and/or cylindrical in shape and so cause less disfigurement of the tree. The elongate body may be adapted for attachment to a tree by being fitted with a fixing member. The fixing member may taper to a sharp end point. The fixing member can be provided with a screw thread for helping insert it into the tree and keep it in place. 
   The biasing device may apply pressure that is usually slightly lower than that pressure resulting from expansion of a growing tree, e.g. 7-8 kg/cm 2 . The biasing device may be formed of a resilient material. In one embodiment the biasing device comprises a compression spring. 
   One end of the biasing device may abut the object. Alternatively, a component, such as a washer or a ring, may be slidably mounted on the elongate body between the object and the tree so that the tree at least partially contacts the component, which transmits the pressure to the object. 
   The elongate body may be comprised of a plurality of elongate members, each of which may be generally cylindrical and/or have a smooth surface. The plurality of elongate members may be connected together by means of corresponding threaded projections and bores. The length of the elongate body can therefore be extended by inserting further elongate members. 
   Some or all of the components forming the device may be formed of plastics or metal, such as stainless steel. The object may be part of a lightning protection system for the tree, e.g. a cable clip. 
   According to another aspect of the present invention there is provided a device for fixing an object to a tree, the device including: 
   an elongate body, one end of which is adapted for attachment to a tree; 
   an object slidably mounted on the elongate body, and 
   a device for biasing the object towards the end of the body adapted for attachment to the tree, 
   in use, pressure resulting from growth of the tree being transmitted to the object and pushing it along the elongate body against the bias and away from the tree. 
   According to yet another aspect of the invention there is provided a lightning protection system for a tree including a device substantially as described herein. 
   Whilst the invention has been described above, it extends to any inventive combination of the features set out above or in the following description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be performed in various ways, and, by way of example only, an embodiment thereof will now be described, reference being made to the accompanying drawings, in which: 
       FIG. 1  is an exploded diagram of an embodiment of the device; 
       FIG. 2  illustrates schematically the device in use. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The device is generally indicated at  10  in  FIG. 1 . The device  10  includes four main components  12 ,  14 ,  16 , and  18  which make up an elongate body. The screw-like component  12  located at one end of the elongate body acts as a fixing member. The component  12  has a head portion  13 A leading to a tapering portion  13  that in turn leads to a sharp pointed end. The tapering portion  13  is provided with a screw thread. Within the free end of the head portion  13 A there is a threaded blind bore. In an alternative embodiment, the fixing portion  12  may include separate head and thread portions. 
   The device  10  has a central portion which, in the example, is formed of two substantially cylindrical components  14 ,  16  that have smooth curved outer surfaces. A threaded projection extending from one end of the cylindrical component  14  fits into the blind bore of the fixing component  12 . The other end of the cylindrical component  14  includes a threaded blind bore  15 A. The component  16  is substantially identical to the component  12  and has a threaded projection  17  which is used to connect it to the bore  15 A of the component  14 . 
   The other end of the component  16  has a blind bore  17 A. It will be appreciated that further components such as the components  14  or  16  can be used to extend the overall length of the device  10 . It will also be understood that the components making up the central portion need not be identical in length. Alternative means of attaching the components together can be used, e.g. adhesives or clips. 
   When the device is assembled the components  12 ,  14 ,  16  will usually be screwed together first. Optionally, a washer  20  is then be slipped onto the elongate body formed by the components, the washer abutting the head  13 A of the fixing component  12 , which helps prevent it from sliping onto the tapering portion  12 . An object to be fixed to the tree, such as cable clip  24 , can then be threaded onto the device so that it abuts the washer  20  (if fitted). The cable clip  24  has a central aperture of a diameter substantially similar to that of the cylindrical components  14 ,  16 . This type of clip is particularly suitable for use with the device, but it will be appreciated that the object could be any suitable body that needs to be fixed to a tree. 
   A compression spring  22  is then fitted over the cylindrical components  14 ,  16  to encircle them. A first end of the spring  22  abuts the cable clip  24 . The spring  22  has a diameter slightly greater than that of the central cylindrical portions of the device so that it can easily be compressed/uncompressed. 
   The final stage of assembling the device  10  normally involves screwing an end piece  18  into the bore  17 A of the component  16 . The end piece  18  can be a nut having a threaded projection  19  and a head portion  19 A having a diameter greater than that of the cylindrical components  14 ,  16 . A second optional washer  19 B can be fitted between the head portion  19 A and the cylindrical component  16 . If this is done then a second end of the spring  22  will normally abut the washer  19 B instead of the head  19 A. 
   Turning to  FIG. 2 , the device is shown fixing the cable clip  24  to a tree  32 . The threaded portion  13  and possibly part of the head portion  13 A is screwed/pushed into the side of the tree. Thus, the device  10  can project outwards from the side of the tree at an angle of around 90°. The bias provided by the spring  22  helps retain the clip  24  adjacent the outer surface of the tree  32 . Thus, in the case of an object that is not threaded onto the device  10 , pressure from the spring can retain it on the body of the device during normal use. In an alternative embodiment, a tube of resilient material or a plurality of springs may be used to provide the bias on the object. 
   A growing tree will typically exert an outward pressure of around 8.44 kg/cm 2  (120 psi). The spring  22  is selected so that it can exert a pressure slightly lower, e.g. 10%, than this so that is does not substantially inhibit the growth of the tree. Typically the pressure exerted by the spring may be in the range of 7-8 kg/cm 2 . As the tree grows, the washer  20  and the clip  24  are pushed against the bias of the spring  22  towards the end piece  18  of the device  10 , which can help prevent the clip  24  at least from becoming embedded in the tree. 
   A version of the device tested by the inventor includes cylindrical components  14 ,  16  which provide a total length of around 8 cms and a diameter of around 7 mm. The device further comprises a compression spring of around 56 mm in length in its uncompressed state and a diameter of around 10 mm. These components are estimated to prevent the clip from being embedded by the tree for around five years after it has been fitted. Thus, the device may not need any modifications or attention over this period. 
   The tree may eventually grow to a size which would mean that the clip  24  is in danger of being embedded or causing damage to the tree or the device is at risk of failing. At this point the end piece  18  of the device can be removed and a further smooth cylindrical portion can be fitted. It may also be necessary or desirable to replace the spring  22  with another one having different dimensions to exert a pressure of a different magnitude. The end piece  18  is then replaced so that pressure is again exerted on the clip  24 . 
   The embodiments described above can be produced at low cost. The components are typically formed of durable materials such as plastic or metal, e.g. 316 stainless steel, which are intended to damage the tree as little as possible if they become embedded. The device can therefore provide a cheap and reliable way of attaching an object to a tree whilst reducing the risk of damage.