11. Thirty parallel lines were drawn inside the quadrant, and trigonometrical calculations were done graphically. 12. This was very similar to the instruments used in France and Britain for previous trigonometrical surveys. 13. The earliest European recorded to have ascended was James Sprent and his trigonometrical party in 1853. 14. Thanks to the advent of Global Positioning System technology, the trigonometrical station is now redundant. 15. In this capacity he made substantial contributions to the on-going Trigonometrical Survey of India. 16. John MacCulloch visited Balta in May 1820 to carry out the Trigonometrical Survey for the Ordnance Survey. 17. Drummond used the Drummond light which was employed in the trigonometrical survey of Great Britain and Ireland. 18. Their granddaughter Pauline Georgiana Plowden married Henry Haversham Godwin-Austen of the Trigonometrical Survey of India. 19. Sprent was appointed temporary assistant surveyor in August 1833 and was soon placed on the trigonometrical survey. 20. From 1968 to 1972 he was a trigonometrical calculator for the shipbuilders, then becoming a Pipework planner.
