Entry: Drain Periscope originally posted by Kay O. Sweaver |
N. Basically a more advanced version of a Manhole Peeper, the Drain Periscope's purpose is to allow explorers to see where they are on the surface from below a manhole. This eliminates the risk of popping a manhole in a busy street or in front of a police station and also gives visual clues as to your location relative Top Side. The periscope is built using PVC or copper tubing small enough to fit through the manhole vents or grille, two small mirrors are then inserted at 45 degree angles allowing a view of the surface like a submarine periscope. If you have a sufficient knowledge of optics this can be further enhanced by adding a wide angle "fisheye" lense like on the Manhole Peeper. |
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