Appendix I 349 



to detach themselves after driving the brass "sounding tube" to 

 which they were attached deep into the floor of the ocean, where it 

 is filled with mud, and whence it can readily be raised to the sur- 

 face. The process of making deep-sea researches of every kind is 

 full of interest, and the student should, if possible, read the descrip- 

 tions in the works referred to at the end of Chapter XL 



