Seattle Home Inspector's Blog


Dry Turtles! Florida Keys and the Dry Tortugas

     My Sweetie and I recently made a trip to the Florida Keys----including the Dry Tortugas National Park.  A single blog post can not possibly cover all the things we did, but I do want to do at least two or three posts on some of the more impressive aspects of the trip.  Other details will likely come out in comments and/or Wordless Wednesday pictures in the future.

Approaching Fort Jefferson by water

     Perhaps the most impressive aspect of the trip was our visit to the Dry Tortugas.  I am by no means a “historian” and have little interest in merely recapping the small bits of information imparted to us by our guide for the day.  There are lots of resources one can find on the Internet or in the Library that can go into more meaningful detail than I could ever do in a blog.  While I find the history of these places fascinating, it is how they fit into current information and how they are useful to us today that I find interesting.  This post will set the stage for a post to come later---perhaps tomorrow. Each picture will have additional information if you run your cursor over it.

     In a “coconut-shell,” the Reader’s Digest version of the Cliff Notes of the Fort is that construction on the Fort----known as Fort Jefferson----began in 1846 and took 30 years to build----but was never actually completed as designed.  Designed to house 4000 soldiers it never had more than around 2000.  No cannons were ever fired outside of practice rounds.  The fort's biggest guns could throw a 242 lb ball of iron 3 miles.  Surely any wooden ship would think the sky was falling.  The fort was designed to function as a support facility to provide supplies for naval ships that could control the gulf.  So even though the fort itself never saw action it was hugely successful as a support facility for the ships that did.  The fort itself took so long to build that its smooth bore cannon were outdated by newer technology before it could be completed.  Working conditions were horrible with yellow fever running rampant and no knowledge of what caused it.

     Anyone that has ever 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 with your clothing being made of a type of crude wool popular with the army----winter or summer.  Oh and did I mention “winter” is really 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 their 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.

     One of the first things one notices about the fort is that it is hexagon shaped----and that the sides are not equal so as to better fill up the shape of the island.  Another striking characteristic of the fort is that there is a moat all the way around it.  Well everyone knows a good fort always has to have a moat around it, plenty of alligators in the moat and of course a draw bridge.  Well in this case the moat was simply a deep depression all around the fort that was dug out to get fill for the walls of the fort.  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 an almost limestone like concrete----very good at absorbing impact.  The over 16 million bricks were used 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 fortification in the world.  Tremendous amounts of this fill were needed to create the fort structure----all of which had to be dug----BY HAND-----from around the fort where the moat is.  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.

The entrance to the fort----there used to be a draw bridge

Looking West---along the South Moat

     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 very 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 that the 30 year construction time frame lapped the time frame of the civil war.  This fort stayed in Union Hands during the war but obviously the south was not about to co-operate and provide the brick any longer during the war.  So they brought it 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 is also that same red brick and thus consistent with the moat being constructed at this later time.

Trying to keep the ocean away

The West Moat

     Another interesting foot note is that all of the floors that the cannon sat on inside the fort structure 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.

Look carefully at the floor and note the arcs of the cannon that were mounted on the granite slabs

Smaller 32 lb shot cannon

     It is the 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 Post in this series.

Charles Buell

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Comment balloon 25 commentsCharles Buell • December 17 2009 02:34PM
Dry Turtles! Florida Keys and the Dry Tortugas
My Sweetie and I recently made a trip to the Florida Keys----including the Dry Tortugas National Park A single blog post can not possibly cover all the things we did, but I do want to do at least two or three posts on some of the… more