viil PREFACE 



But the men of science fifty years ago were not 

 disposed to take this view of the matter. Pushing 

 their inquiries as to the character of the sea-fauna 

 into deeper and deeper water, they at length de- 

 manded information as to the existence of forms of 

 animal life in the greatest depths. Unable them- 

 selves to bear the heavy expenses involved in such 

 an investigation, they sought for and obtained the 

 assistance of the Government, in the form of national 

 ships, for the work, and then our knowledge of the 

 depths of the great ocean may be said to have com- 

 menced. 



We know a good deal now, and in the course of 

 time we may know a great deal more, about this 

 interesting region ; but it is not one which, in our 

 generation at any rate, any human being will ever visit. 



We may be able to plant the Union Jack on the 

 summit of Mount Everest, we may drag our sledges 

 to the South Pole, and we may, some day, be able to 

 travel with ease and safety in the Great Sahara ; but 

 we cannot conceive that it will ever be possible for 

 us to invent a diving-bell that will take a party of 

 explorers to a depth of three and a half miles of 



