1 62 POPULAR SCIENCE MONTHLY. 



successful, one may easily recall the French 'Le Plongeur,' the 'Gustav 

 Zede/ the 'Morse/ the 'Narval,' the Nordenfeldt boats and those of 

 Goubet and Baker. Here also belong, of course, the latest and most 

 successful boats of all, the 'Holland' and Mr. Lake's 'Argonaut,' of 

 which some account will follow. 



Turning now from the history of submarine navigation to a con- 

 sideration of certain practical problems connected with it, we are 

 brought at the outset face to face with a fact of fundamental sig- 

 nificance, namely, that even with the aid of very powerful electric 

 illumination it is not possible to see clearly through ordinary sea 

 water for more than a few feet. According to Mr. Lake of the 'Argo- 

 naut,' about fifteen feet is the limit of visibility in our Northern waters, 

 and about twice that in Southern. Submarine navigation is like navi- 

 gation in the densest sort of a fog. High speed under water is just as 

 possible mechanically as upon the surface. But the fact just stated 

 is a death blow to high speed. Unless there shall be discovered some 

 hitherto unsuspected means of perceiving at a distance invisible ob- 

 jects, high speed will unquestionably be fraught with great peril. 



For the same reason it will probably be found impracticable to 

 attempt very long journeys under water. There will probably never 

 be trans-sub-atlantic lines, much less submarine greyhounds. 



In fact, practical inventors of submarine craft, at least of late years, 

 have ceased to attempt to provide more than a surface-going boat which 

 shall be able at any time or place to dive beneath the surface to the 

 depth desired, to remain under water for considerable periods of time, 

 either stationary or moving, with both safety and comfort to the crew, 

 and then, the purpose of the dive having been accomplished, to return 

 speedily and safely to the surface. Even these requirements constitute 

 a pretty large contract, but that they have been met satisfactorily ap- 

 pears sufficiently, so far as the 'Holland' at least is concerned, from the 

 quotations given at the beginning of the article, and from the further 

 fact that our government, ultra-conservative in adopting new devices 

 for use in warfare, has purchased the 'Holland,' which is now at New- 

 port in charge of Lieutenant Caldwell, Admiral Dewey's aid at Manila, 

 and that Congress has authorized the building of six more 'Holland' 

 boats of an improved type. Two of these are now being built at the 

 Union Iron Works, at San Francisco, the rest at Elizabethport, N. J. 



Obviously, a prime essential for any sojourn under water is an ample 

 supply of pure air. When possible to make use of it there is but one 

 rational source of pure air, and that is the exhaustless supply at the 

 surface. Provided she herself secures it, a submarine boat does not 

 in the least surrender her independence by utilizing this supply. This 

 the 'Argonaut' does at ordinary depths by means of a pair of vertical 

 tubes, one for inflow, the other for discharge. 



