Lighthouses are so cool and they use so many aspects of STEM. 
I don’t know if Barton saw a lighthouse during his travels, but I’m sure he read about them. 
Barton was curious that way. I hope you too, are curious like that.

I've never heard of a lighthouse on the North Raccoon River, so he didn't see one at Adel.
But he did look after the Courthouse clock tower, so there are similarities.
A back-lit clock tower is kind of like a lighthouse on the prairie. 

About lighthouses:
First, a tall, narrow-ish building that can be built at the edge of the sea and may need to withstand the pounding of the waves during a storm. This is a scientific accomplishment. 
Before electricity, American lighthouses were fueled by whale oil or colza or other types of oil. 
Lighthouses switched from oil lamps to electric light during Barton’s lifetime. 
A Fresnel lens, which could be made from sand, seashells and wood ashes, is able to direct and concentrate loose photons into a beam, and project that beam up to 20 miles out to sea.  Wow!

If you are a mariner, and get blown off-course in a storm, but then see a light house, how do you know where you are? 
In the day time, the shape and paint design tells you which lighthouse you are seeing. They are each different. 

So what about at night or when during a storm? 
The lighthouse lens rotates, and each lighthouse rotates at its own particular speed, which helps tell mariners where they are.  
A Fresnel lens is made of many panes of glass, and can be custom-built to have panes of colored glass that makes each lighthouse unique. 

Just as you can tell when your teacher is walking down the hall by her footsteps, so you know to be quiet, mariners can tell what lighthouse they are near by looking at the lighthouse. And ship navigators keep maps to tell them what kind of coastline is near each lighthouse. 

Oh, and how did the lighthouse lenses rotate, back in Barton’s day? 
Did the lighthouse-keeper stay up all night and turn the light by hand? 
Most lighthouses worked like Barton’s clocktower, on a weighted rotation system; 
with the height of the tower allowing for weights on long cables.
Powered by gravity. 

I hope to see a lighthouse someday, and wish there was one powered by weights. 

Eric J. Rose 
photo, and webpage with great info:
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