The mighty stone tower still remains for many purposes the most effective method of lighting the pathways of the sea, but it is both exceedingly difficult to build, and it is very expensive. Within comparatively recent years busy inventors have thought out several new plans for lighthouses, which are quite as wonderful and important in their way as wireless telegraphy and the telephone are in the realm of electricity.
One of these inventions is the iron-pile or screw-pile lighthouse, and the other is the iron cylinder lighthouse. I will tell the story of each of them separately.
The Lighthouse on Stannard Rock, Lake Superior.
This is a stone-tower lighthouse, similar in construction to the one built with such difficulty on Spectacle Reef, Lake Huron.
The skeleton-built iron-pile lighthouse bears much the same relation to the heavy stone tower lighthouse that a willow twig bears to a great oak. The latter meets the fury of wind and wave with stern resistance, opposing force to force; the former conquers its difficulties by avoiding them.
A completed screw-pile lighthouse has the odd appearance of a huge, ugly spider standing knee-deep in the sea. Its squat body is the home of the keeper, with a single bright eye of light at the top, and its long spindly legs are the iron piles on which the structure rests. Thirty years ago lighthouse builders were much pleased with the ease and apparent durability of the pile light. An Englishman named Mitchell had invented an iron pile having at the end a screw not unlike a large auger. By boring a number of these piles deep into the sand of the sea-bottom, and using them as the foundation for a small but durable iron building, he was enabled to construct a lighthouse in a considerable depth of water at small expense. Later builders have used ordinary iron piles, which are driven into the sand with heavy sledges. Waves and tides pass readily through the open-work of the foundation, the legs of the spider, without disturbing the building overhead. For Southern waters, where there is no danger of moving ice-packs, lighthouses of this type have been found very useful, although the action of the salt water on the iron piling necessitates frequent repairs. More than eighty lights of this description dot the shoals of Florida and adjoining States. Some of the oldest ones still remain in use in the North, notably the one on Brandywine shoal in Delaware Bay; but it has been found necessary to surround them with strongly built ice-breakers.
Two magnificent iron-pile lights are found on Fowey Rocks and American Shoals, off the coast of Florida, the first of which was built with so much difficulty that its story is most interesting.
The Fowey Rocks Lighthouse,
Florida.