| 摘要 |
<p>Conventional methods of marking land boundaries usually suffer from the following disadvantages, they are intrusive in areas of natural beauty, liable to vandalism and erosion, expensive to install and, over many years, can become lost in undergrowth or shifting topsoil. It is suggested to use high power permanent magnets buried at a depth of 1.5 to 2.5 metres. Permanent magnets hold their magnetic properties for many hundreds of years and can be easily detected using gradient-magnetometers, using the flux gate principle . They can be installed in a protective plastic sheath by drilling a hole in the ground and dropping them in. If several magnets are buried in close proximity, they can be of differing strengths, thus enabling easy identification.</p> |
