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296
A. Alcock—New Species of Oxyrhynch Crab.
[No. 2,
exception of those belonging to the Regular system, ought to polarise light. But this could not be verified in the case of crystals opaque to light. There is no such difficulty with electric rays, for all crystals are transparent to them. As a matter of fact, all the above experiments with one exception were performed with specimens opaque to light.
Explanation of the plate
- R … metallic box containing the Ruhmkorff's coil.
- S … position of the sparking balls.
- L … position of the convex Lens.
- P … the Polariser.
- I … Iris diaphragm.
- K … the Crystal.
- A … the Analyser.
- C … the Coherer.
- G … the Galvanometer. In practice the Galvanometer is placed at a greater distance and the leading wires enclosed in tin-foil.
(Lower portion not transcribed)
