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Lighthouse keeping has always sounded like a romantic occupation to me. As a kid, I even won honorable mention in a creative writing contest with a story featuring a lighthouse keeper.
Of course, being a prairie boy, I had never actually even been in a lighthouse. And that held true until just recently, when, on a trip to Ontario, I climbed two of them, on the shores of Lake Huron.
Lighthouses are not a new invention. The Lighthouse of Alexandria, one of the Seven Wonders of the World in ancient times, was built in the third century B.C. and stood something between 115 and 135 metres in height.
Lighthouses proliferated in the seventeenth century, as ships ranged across the world. The first Canadian lighthouse was built at the entrance of the harbour of the Fortress of Louisbourg between 1731 and 1734. Lighthouses arrived on the Great Lakes seventy or eighty years later.
I visited the Kincardine Rear Range Light, built in 1881, and the Point Clark light, built in the early 1850s.
The Kincardine light is a pretty tower atop the lightkeeper’s house. The Point Clark Light is what most people think of as a lighthouse: a circular limestone tower approximately 27.5 metres tall.
The Point Clark light warns of a dangerous shoal. The Kincardine light is the rear half of a set of “range lights,” with the front range light at the end of a narrow spit further out in the lake. If an incoming ship keeps the front and rear range lights aligned, it will unerringly find the safe channel into the protected harbor.
The first lighthouse lights were bonfires. Candles, whale-oil lamps and kerosene lamps followed, then acetelyne gas and finally electricity. But whatever the source of light, the challenge remains the same: ensuring it is visible many kilometers out from the shore.
The earliest attempt to intensify lighthouse lights were parabolic reflectors, but in the 19th century, Fresnel lenses took over.
Invented in 1822 by French physicist Augustin Jean Fresnel, Fresnel lenses are flat on one side and ridged, in a series of concentric rings, on the other. Each ring focuses the light toward the centre. The result is a relatively light, thin, lens that can focus light as well as a much larger, heavier ordinary lens–and much, much more efficiently (focusing 85 percent of a lamp’s light) than a parabolic reflector (which could only focus about 20 percent).
The lenses were arranged into an array that rotated around the light source, causing a beam of light to sweep the surrounding horizon. When the lenses were aimed toward you, the light looked bright; when the lenses were aimed away from you, the light looked much dimmer. The effect was of a flashing light, and each lighthouse could be identified by the specific pattern of flashes it emitted, created by the design of the lens assembly.
Before electricity, the lens assembly was rotated by weight-driven clockwork, just like in a grandfather clock. The lighthouse keeper had to keep the assembly wound, sometimes as often as every two hours. To reduce friction, the lens assembly often floated in mercury.
As time went along, electric lights and motor drives powered by diesel electric generators came into use. Both lighthouses I visited still have rotating lens assemblies, using Fresnel lenses, although thankfully no pools of mercury were to be seen.
Modern navigational aids, like the Global Positioning Satellite system, have almost killed off lighthouses. There are only about 1,500 working ones left, and the newest ones very different from the classic examples I climbed: they’re typically just skeletal steel towers topped by either the kind of rotating lights you see at airports or flashing strobe lights, and often powered by solar-charged batteries.
I’m glad I had the chance to climb classic examples, now protected as heritage sites. But as I puffed my way up the increasingly narrow and steep steps of the Point Clark lighthouse, I was even more glad I only had to climb it once.
Lighthouse keeping, it seems, like much of the past that sounds romantic to modern ears, consisted mainly of backbreaking work.
I think I’ll stick to writing.
