Like most people, I have been using the word limelight for many years without knowing (or even considering) its origins. Lately, I happened to read Richard Kirwan’s excellent If Maps Could Speak — a history Ireland’s Ordinance Survey and memoir of the man responsible for dragging it kicking and screaming into the third millennium — wherein the central importance of the limelight to the huge mapping project of Ireland undertaken in the first half of the nineteenth century was described. At the beginning of the nineteenth century, Ireland was largely unmapped. Her colonial masters in Westminster, deciding that this situation was unacceptable, put the wheels in motion to mobilise a veritable army of mappers and sappers, so that by the time of the Great Famine (1845-50) an impressive jigsaw of six-inch maps covered every nook and cranny of the country. By independence in 1922 Ireland was the best mapped country in the world.
None of this mapping could have been achieved without the skill, pluck and resolve of the officers and men of the Ordinance Survey (a branch of the military in those days), but it was the increasing sophistication of the tools at their disposal that really made their work possible: theodolites, composite metal measuring bars and our friend, the limelight. Without the benefit of aerial photography, or, God forbid, satellites, the cartographers of the nineteenth century had to rely on that most hated and arcane of fields, trigonometry, to measure distances. To kick off the process of mapping Ireland, the country was divided into a framework of triangles. Men such as Thomas Colby, who led the Ordinance Survey in Ireland, would scale the country’s mountains, sometimes in hazardous weather conditions, pitch their tents and attempt their observations and calculations. How did these men make their observations in rainy or foggy weather (sometimes it can take a couple of weeks for the mist to lift off a mountain in the west of Ireland) or at night? I’ll let Richard Kirwan take up the story:
[My colleague] pointed to a strange outline sketch on a wall of the office, like something Michelangelo might have drawn.
“What’s that?” I asked.
“That’s the limelight, invented by Thomas Drummond.”
It was an astonishing invention — a tiny ball of lime lit by a mixture of oxygen and alcohol, giving out an intense light that could be seen up to seventy miles away. Nothing else could match it at the time. The limelight was designed principally to overcome the difficulties in observing at night the long distances between the Irish mountain-tops. It was also needed to take advantage of the tiny breaks that the misty and cloudy weather allowed on the mountains.
Thomas Drummond was a Scottish engineer who was, in modern parlance, headhunted by Colby to assist with the mapping of Ireland. Drummond had worked on the surveying of the Scottish Highlands and was something of a superstar of the cartography world in the early 1800s — so much so that Wordsworth immortalised him by referring to him as “Drummond of calculating celebrity”. Drummond’s limelight went on to be used in theatres and music halls, and it is from this world that limelight has entered everyday parlance.