Aquascope

The underwater viewer can be used for observing reefs, checking boat moorings, secchi disks and other survey work.

It is also used as educational tool to watch plants, creatures and habitats underneath the surface of rivers, lakes and seas.

[7] The instrument which has been popularly named the Water, or Marine Telescope, from the power given by its use to see into the water, consists of a tube of metal or wood, of a convenient length, to enable a person looking over the gunnel of a boat to rest the head on the one end, while the other is below the surface of the water; the upper end is so formed, that the head may rest on it, both eyes seeing freely into the tube.

[8] A very convenient size for the instrument represented in the above figure, is to make the length AC, 3 feet, and the mouth A, where the face is applied, of an irregular oval form, that both eyes may see freely into the tube, with an indentation on one side, that the nose may breathe freely, not throwing the moisture of the breath into the tube.

Holes must be provided at the junction of B to C, for the purpose of allowing the air to escape, and bring the water into contact with the glass; on each side there is a handle for holding the instrument.