This is a great low-tech idea. An ingenious update of the 19th century ship deck prism: http://www.scientificsonline.com/deck-prism.html http://www.scientifics

This is a great low-tech idea. An ingenious update of the 19th century ship deck prism: http://www.scientificsonline.com/deck-prism.html http://www.scientificsonline.com/deck-prism.html