Two experiments on the reaction to ultra-violet light of certain sound scatterers in the area are described.
The source was a 125 W. ultra-violet lamp.
The scatterers were detected using a Kelvin and Hughes recording echo-sounder, type 22.
The traces on both occasions were of the confused type caused by a number of different organisms, apparently lying between 20 and 60 m. and 8 and 30 m. respectively.
The responses of the different organisms to the ultra-violet light as shown by the components of the traces are described and their speeds of reaction calculated.
The types of organisms causing the traces are suggested.