Tall Towers of Iron

Tall Towers of Iron, 1844-1881

Cast iron is an alloy of iron with carbon and silicon which can be cast into any desired shape in molds. It was invented in the seventeenth century, but it was not until the later part of the eighteenth century that it became possible to cast sheets of iron large enough to assemble into buildings. As a material for constructing lighthouses, cast iron had many advantages. It is light in weight. When properly assembled, it is watertight and weathers well, even in a salt-air environment. Cast iron lighthouses, prefabricated offsite, can be quickly assembled by relatively small crews of workers. If the lighthouse is threatened later by beach erosion, it is relatively easy to disassemble the tower and reconstruct it at a safer location.

The first cast iron lighthouse was built at Swansea, Wales, in 1803. However, it was many years before cast iron began to be used in lighthouse construction in the Americas. In 1841, a cast iron lighthouse prefabricated in England was built at Morant Point in Jamaica. In 1846, the British completed the Gibbs Hill Light in Bermuda, a 117-foot cast iron tower that remains in service today.

In the U.S., the relatively low cost of cast iron probably appealed to Stephen Pleasonton, the Fifth Auditor of the Treasury and the pinch penny supervisor of U.S. lighthouses. In any case, he authorized the building of a small cast iron lighthouse at Long Island Head, Boston Harbor, in 1844. Prefabricated by the nearby South Boston Iron Company, the tower was built in three sections 7 feet high. It was 12 feet in diameter at the base and only 6 feet in diameter at the top, so the lantern, perched atop the narrow tower, gave the lighthouse a "big-headed" appearance. This lighthouse was demolished in favor of a larger cast iron tower in 1881. A second cast iron tower, essentially identical to the Long Island Head tower, was built in 1846 on Lake Champlain at Juniper Island, Vermont. The Juniper Island Light remained in service until 1954 and survives today in private ownership.

Apparently encouraged by these successful projects, Pleasanton decided to use cast iron for three taller towers needed on the Gulf Coast. The 65-foot lighthouses were prefabricated by Murray and Hazlehurst, a Baltimore foundry, and erected at Biloxi, Mississippi, in 1848 and at Point Bolivar and Matagorda Island, Texas, in 1852. Construction of the two Texas towers was supervised by Hiram Runnels, the superintendent of lighthouses at Galveston, and the lanterns were installed by Calvin Knowlton, who did similar work at St. Marks, Florida, and other Gulf lighthouses.

These three towers are very similar in design to the Long Island Head and Juniper Island lights, with conical towers strongly tapering to a narrow top. The Biloxi Light, a miraculous survivor of the Civil War and countless hurricanes, preserves this design for us to see today. After the Civil War, the Point Bolivar Light was replaced, as we shall see, by a taller tower. The Matagorda Island Light was disassembled; when it was rebuilt in 1873, farther from the water, it was extended in height to 79 feet by adding a cylindrical section at the top. However, it still has the characteristic "big-headed" appearance of the Pleasonton towers.

Biloxi Light, Mississippi
National Park Service photo

Monomoy Point Light;
Monomoy National Wildlife Refuge photo
One other cast iron lighthouse was built during the Pleasanton era, the 1849 tower at Monomoy Point, Massachusetts. This 40-foot lighthouse has a unique design. Instead of having the strong taper seen in the other early towers, it is narrowly cylindrical in shape.

An early inspector complained that the Monomoy Point tower was "neither large enough, nor high enough, nor stiff enough." The fact that a cast iron tower sways in the wind much more than a solid masonry tower was disconcerting to keepers, then and later. Partly to reduce the sway, the Monomoy Point lighthouse and many cast iron light towers were eventually lined inside with brick. The brick provides additional structural support, it reduces the sway, and it provides some insulation against the winter cold and summer heat.

Pass a l'Outre, Louisiana
photo © Lighthouse Depot Online,
used by permission
As soon as it was organized, in 1852, the Lighthouse Board began planning the construction of taller lighthouses, some of them in cast iron. In the south, the basic cast iron design of the earlier administration was scaled up to a height of 85 feet for the 1855 lighthouse at Pass à l'Outre, Louisiana, marking one of the mouths of the Mississippi. Construction of this lighthouse was supervised by Danville Ledbetter, an Army officer who later served as a general in the Confederate Army. (Ledbetter also built the Sabine Pass Light in 1856). Now sinking inexorably into the mud, the critically endangered Pass à l'Outre Light still carries its antique lantern.

After the Civil War ended, the Pass à l'Outre design was scaled up again, with a longer taper, to create the 117-foot second lighthouse for Point Bolivar. This lighthouse, completed in 1873, carries a bigger lantern designed for a first-order Fresnel lens (the lens now displayed a the Smithsonian Institution in Washington, DC). Inactive since 1933, Point Bolivar Light has been privately owned since 1947. Its horizontal-stripe daymark has disappeared, and the lighthouse now stands cloaked in rust.

Point Bolivar, Texas
photo © Lowell Thomas,
Gulf Coast Lighthouses,
used by permission

Cape Henry, Virginia
National Park Service photo
In the late 1850's it might have seemed likely that tall cast iron lighthouses represented the wave of the future in lighthouse construction, but this wasn't to be the case. In fact, only three more were built. Construction of the 145-foot lighthouse at Cape Canaveral, Florida, began before the start of the Civil War, but the tower wasn't completed until afterwards, in 1868. This remarkable building has a unique profile, sharply tapered from a wide base, unlike any other U.S. lighthouse. The lighthouse was relocated further inland in 1894, although this turned out to be unnecessary; the original foundation survives.

In 1875, the Lighthouse Board completed a 135-foot cast iron lighthouse at Hunting Island, South Carolina. It stood only 14 years before rapid beach erosion forced the Board to have it relocated inland. Beach erosion has resumed in the area, and the lighthouse may need to be moved again sometime in the future.

The last tall cast iron tower built was a 165-foot tower at Cape Henry, Virginia, marking the entrance to the Chesapeake Bay. This lighthouse replaced an early Federal octagonal built in 1792 by John McComb. The Board also gave the new lighthouse an octagonal design. Completed in 1881, Cape Henry Light remains in service today, still using the original first order Fresnel lens. The beachfront is stable at Cape Henry, and the lighthouse has not required any relocation.

Cape Canaveral, Florida
National Park Service photo

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