Photo above: Approaching Fort Jefferson. All photos courtesy of Charles Buell.
Home inspectors never really go on vacation. It is really impossible for me to go anywhere and not be interested in seeing how the buildings are constructed and how things are done differently around the world. A few years ago, my sweetie and I took a trip to Dry Tortugas National Park, located 70 miles off the shores of Key West, Fla.
I am, by no means, a historian, and I have little interest recapping the small bits of information imparted to us by our guide as we toured Fort Jefferson at Dry Tortugas. For those who are interested, the history, in detail, can be found on the Internet or in a library (www.drytortugasinfo.com/history.html). What I find more interesting than history is how the structures fit into current information and how they are useful to us today. This article sets the stage for a second one to come next month.
30 years and never finished to design
Briefly, construction on Fort Jefferson began in 1846, continued for 30 years, but never was completed as designed. Designed to house 4,000 soldiers, there never were more than 2,000 there. No cannons were ever fired outside of practice rounds. Its biggest guns could throw a 242-lb ball of iron three miles. Surely any wooden ship would think the sky was falling if struck by such a bulkhead buster. The fort was designed to function as a support facility to provide supplies for naval ships controlling the Gulf of Mexico and the Straits of Florida. So, even though the fort never saw action, it was hugely successful as a support facility for the ships that did see action. One of the reasons it never saw action was because it took so long to build, its smooth bore cannons were outdated by newer technology before it could be completed. Several factors contributed to it not being completed as planned.
One was that working conditions were horrible with yellow fever running rampant with no knowledge of what caused it.
Anyone who has been to the Florida Keys knows how hot and muggy it can get. Now, add to that building a brick fort in the hot sun, wearing clothing made of the crude wool popular with the army winter and summer. Oh, and did I mention winter is just a designation on a calendar as opposed to an actual event? Oh, and did I mention the mosquitoes?
My guess is that no one involved in the tedious business of moving the tons of granite and slate used in the floors throughout the prison could have ever, in his wildest fever-induced dreams, foreseen the bikini-clad snorkelers encircling the island today. These could not have been happy times for anyone at the fort and paradise would not have been a prominent word on the enlistment brochures at the army recruiting stations of the day.
Another factor was how it was being built.
One of the first things one notices about the fort is that it is hexagon-shaped and that the sides are not equal. The odd shape functioned to better fit the shape of the island. Another striking characteristic of the fort is that there is a moat all the way around it. Everyone knows a good fort always has to have a moat around it, plenty of alligators in the moat and, of course, a drawbridge. Well, in this case the moat was simply a deep depression around the fort that was dug out to get fill for its walls. Construction of the fort was simply a double-wall brick structure inside and out and the center was filled with coral sand/debris mixed with lime, which solidified into a limestone-like concrete — very good at absorbing impact. The over 16 million bricks functioned as more of a façade to hold this coral construction in place. This fort became one of the largest, if not the largest, fired-brick fortifications in the world. Tremendous amounts of this fill were needed to create the structure. It all had to be dug — by hand — from around the fort, thereby creating the moat. At some point, the builders realized they needed to keep the ocean from directly impacting the fort, so they built the moat wall that you can see surrounding the fort.
Above: The entrance to the fort — there once was a drawbridge
Above: Looking to the west along the south moat. Note the two layers of brown brick and the top layer of red brick on the fort — and the red brick of the moat wall. Photos courtesy of Charles Buell.
Also, obtaining building materials became an issue.
The fort is made up of three types of brick — two types of brown brick that came from the South (Georgia and Florida, if I remember correctly) and red brick from New York. The first brown brick they tried didn’t hold up well to salt water, so they had to get a second kind. If you remember back to the date of the start of construction, you can see the 30-year time frame lapped the time of the civil war. This fort stayed in Union hands during the war, but obviously, the South was not about to cooperate and continue to provide the brick during the war. So, the brick had to be brought all the way from New York. You can see the clear color change of the top layers of red brick that run all around the top of the fort. The moat wall also is that same red brick, thus consistent with the moat being constructed at this later time.
Above: Trying to keep the ocean away.
Above: The west moat. Photos courtesy of Charles Buell.
The tragic design flaw
The floors inside the fort where the cannons sat were made of giant slabs of slate and granite. Each had to be set — by hand! These granite slabs were interspersed, where necessary, with the slate because the granite would hold up better to the iron cannon guides and supports.
Above: Look carefully at the floor and note the arcs of the iron cannon guides on the granite slabs.
Above: Smaller 32-pound shot cannon. Photos courtesy of Charles Buell.
It was this use of iron in the structure that would become the tragic design flaw of the whole fort. This flaw has created what will perhaps be an insurmountable barrier to long-term preservation of the fort. And now the stage is set for the second article in this series — watch for it in next month’s ASHI Reporter.