Sunday, March 8, 2009

Fresnel lens

Meant to post this earlier. While I was stuck in Angleton on Tuesday, I went to see the Brazoria County Historical Museum. While I wouldn't call it a tourist spot exactly, they did have a nice collection of reproduction election posters, some dating to the very early days of Texas. I love this sort of thing because you can see how ideas of how to "sell" a candidate evolved as time went on. Early posters are obvious and direct, and so are the "campaign songs" -- specially written for the campaign. As you move towards 1900, the posters become far more elaborate and make extensive use of iconographic details. Hmm... think I need a separate post for this. You also get to see how much quirkier the US used to be. For example, the 1860 election campaign was famously presaged by the Lincoln-Douglas debates over slavery. But I didn't know that neither Lincoln nor Douglas had any electors on the ballot in the state of Texas (or anywhere else much in the south).

In addition to these posters, they had a (real, not reproduction) fresnel lens from an old lighthouse that was demolished to make way for a Dow chemical plant. The picture doesn't do it justice. It's an amazing and beautiful construction. Looking at it, set against a wall with no light source inside, you can see nevertheless how it picks up the ambient light (this picture is taken without a flash, and the room was dimly lit to help preserve the older documents). It's a great demonstration of theory and practice coming together -- the mathematical properties of the lens giving the practical benefit of a maximal use of the amount of light available. Sweet!
Posted by Picasa

No comments:

Post a Comment