8 



THE POPULAR SCIENCE MONTHLY, 



morality -would be broken down by permitting aeronauts to descend 

 into gardens and balconies ; and, above all, the boundaries of empires 

 ■would be jjractifally annulled, and nations in consequence engage in 

 continual war. 



Well is it, then, for humanity that balloons have not proved a very 

 great success. Many extensive voyages and many interesting observa- 

 tions have been made ; but as a flying-machine the balloon has no place. 

 It is the servant of the air, not the master. It must obey a will, piti- 

 less, tickle, sometimes kind, but never trustworthy. The expectation 

 that headway could be made against the wind by means of sails and 

 rudders had no basis in sound theory or sense. A sailing-ship is im- 

 mersed in two fluids of widely differing densities, and its sail is only 

 effective because the water, while supporting, at the same time allows 

 the vessel to move more readily in one direction than another. 



Fio. 3.— Sut.livan'3 Fltino-Machine. (Taken from United States Pateut-GCQcc Keports.) 



A balloon, on the other hand, is totally immersed in an ocean of air, 

 and being of the same weight bulk for bulk, and subject to no exter- 

 nal forces, must necessarily follow the slightest current. One might 

 as well attempt to steer a boat, swept along by a great stream, without 

 wind or oar. It forms an integral part of the current itself. It is a 

 thistle-down blown by an autumn gale. 



