244 TEE BOTTOM OF THE SEA. 



authentic character. We can scarcely be astonished 

 at this when we picture to onrselves the profound 

 ignoiance which prevailed relative to the properties 

 of gases. Aristotle, for example, wishing to demon- 

 strate the weight of atmospheric air, weighed an 

 empty bladder, and the same bladder again when 

 filled with air, and found no difference between the 

 two results. Hardly three centuries ago, the fact of 

 water rising in the tube of a pump was explained by 

 the supposition that Nature abhors a vacuum. 



It is hardly a century since the celebrated astro- 

 nomer Halley, commencing the experiments in sub- 

 marine exploration which have been continued to 

 our time, descended to a depth of 50 feet in a 

 diving-bell which he had constructed. English 

 engineers utilised this invention until the year 1830, 

 in building the immense submarine structures with 

 which they have covered the English coasts. At 

 this time another apparatus, more convenient and 

 at the same time less costly, gradually replaced the 

 diving-bell. 



The object of the diving apparatus, to which we 

 are now referring, is to give to each individual work- 

 man the utmost possible liberty of movement. An 

 impervious habit, made of cloth and metal, allows 

 him a certain liberty of motion, which he cannot 

 possibly have when enclosed in a bell. A pipe com- 



