Cartography

It took six years, starting in the summer of 1784, for the Board of Ordnance to establish the baseline of its triangulation of Great Britain. First they used wooden poles, then glass tubes. After much clearing of furze bushes and ant hills, the baseline ran for more than five miles from Hounslow Heath to Hampton Poor House. The maps of England and Wales were complete by 1870. Scotland had to wait until 1887. The delay was rumoured to have been caused by the superintendent’s concern that surveyors would get in the way of the late summer deer stalking. As a wing of the military, the Ordnance Survey had extraordinary powers. The Surveyors’ Act of 1841 allowed it to trudge, clamber, squelch, measure and interrogate wherever necessary.

Maggie O’Farrell’s two previous historical novels, Hamnet and The Marriage Portrait, made her a household name. Land marks a return to her Irish roots: ‘Every family has its myths and ours was that my great-great-grandfather had worked on the early maps of Ireland.’ The year is 1865 and 31-year-old Tomás, a mapmaker, accompanied by his ten-year-old son Liam, is in the employ of the English redcoats and tasked with surveying and mapping Ireland from top to bottom, rocky outcrop to drumlin.

Versailles was a palace of science, as Anna Ferrari shows in this stimulating and innovative study, accompanying a dazzling exhibition of the same title at the Science Museum, London (until 21 April). Soldiers were subjected to electricity experiments in the Galerie des Glaces. The king watched the dissection of an elephant or a horse in the Menagerie. The latest globes and clocks, microscopes and barometers, miracles of precision and beauty, were, and in some cases still are, on display in the royal apartments. The gardens were exercises in trigonometry and hydraulics as well as planting. Louis XV had the largest and most varied plant collection in Europe.