see it clearly
Marine Telescope
A marine telescope probably will never catch a fish for you, but it may be very useful on a fishing trip.
With it you can locate sunken stumps, submarine weed-beds, and fish-beds themselves. But that is not the best use for it. You can study submarine life, can find no end of pleasure sitting quietly on your boat and watching what goes on in the water beneath you.
The materials required for a submarine telescope are very simple, consisting of a few feet of thin board, a small oblong piece of glass, some wire nails, and a piece of sealing wax. The glass may be three by four inches or larger.
Saw from quarter-inch boards four pieces of the same length, twenty inches, two each of widths to correspond with dimensions of the glass. Nail these together into the box shown open at both ends. Lay the piece of glass over one end and fasten securely in place with pins driven into the wood and twisted over. Large headed tacks may be used instead, if desired, the tacks being driven in the wood and their heads overlapping the glass edges, thus holding the glass in place. Then make the glass end watertight by closing up all seams with the sealing wax.
When in use the glass end is placed in the water while you look down through the open end. The light is thus shut out from all parts except that which must come through the glass end, an inch or two under water. The water telescope is long enough for you to sit comfortably in the boat and still watch the world under water at the same time.