Many British hill tops have a trig point placed by the Ordnance Survey. What is the word 'trig' short for?
Ordnance Survey than the equivalent paper version, but the price per square km falls rapidly with the size of coverage bought. The Ordnance Survey's original maps were made by triangulation. For the second survey, in 1934, this process was used again and resulted in the building of many triangulation pillars (trig points): short (c. 4 feet/1.2 m high), usually square, concrete or stone pillars at prominent locations such as hill tops. Their precise locations were determined by triangulation, and the details in between were then filled in with less precise methods. Modern Ordnance Survey maps are largely based on aerial photographs, but
Pole Hill Pond, MA, Astronomer Royal. It was placed on the Greenwich Meridian and its purpose was to indicate the direction of true north from the transit telescope of the Royal Observatory. The Greenwich Meridian as changed in 1850 and adopted by international agreement in 1884 as the line of zero longitude passes 19 feet to the east of this pillar. At that point (19 feet / 5.8m east) there is an Ordnance Survey trig point placed here to mark the top of the hill. Lawrence of Arabia once owned a considerable amount of land on the western side of the hill