ATMOSPHERIC BOAT. 453 



The apparatus, as represented in fig. 481, is of extreme simplicity, as 

 will be seen at a glance. A small cylindrical boiler, B, connected with a 

 capillary tube, is placed on two supports over a spirit-lamp, in such a manner 

 that the opening from which the steam issues is directly opposite the mouth 

 of the tube, T. This tube, after forming a sudden inclination, terminates at 

 the back of the boat in an inclined drain, R. The steam driven through the 

 tube, T, carries along with it a certain quantity of air, which, forced under 

 the water, propels the boat along. The little vessel soon reaches consider- 

 able speed, leaving a long track behind it. It will be seen that this is not a 

 mechanical apparatus, capable of absorbing force or diminishing the action of 

 steam by causing its condensation. 



Let us now calculate the force engendered by this apparatus. We 

 know that a litre of water at boiling point gives 1,700 times its volume. 

 The steam, as it quickly issues from the opening of the boiler, carries along 

 at least ten times its volume, or 17,000 litres of air, which, driven under the 



Fig. 481. Section of " atmospheric " boat. 



water, assumes an ascending force equal to the difference of the densities of 

 water and air, or about the weight of the displaced water. Therefore in a 

 litre of water transformed into 1,700 litres of the steam, which carries off 

 into the water i,7oox 10 =17,000 litres of air, a force is developed repre- 

 sented by 34,000 kilograms. In fact, by reason of the inclined position of 

 the drain on which the pressure of air acts, and its restricted dimensions, the 

 quantity of force employed in the propulsion of the boat is but a fraction of 

 the total force produced. Moreover, the resistance of traction increases with 

 the size of the boat, and as the dimensions of the inclined pipe cannot be 

 indefinitely enlarged, the result is that the propulsive action is soon insuf- 

 ficient, so that the invention is not, in its present condition, applicable to 

 navigation on a large scale. Its superiority to the steam-engine cannot, 

 therefore, be demonstrated ; and we are only now discussing the contrivance 

 in order to show that it is possible, with only moderately powerful gene- 

 rators and extremely simple mechanical appliances, to obtain considerable 

 dynamic effects, susceptible of more serviceable application than is commonly 

 believed. 



CIRCULATING FOUNTAIN. 



The apparatus given in fig. 482 is the subject of a very charming expe- 

 riment, showing the influence of capillarity on the movements of liquids. 



