CONTRIVANCE A NECESSITY. 179 



ened to afford attachment to a web or flying mem- 

 brane which is stretched between them. In other 

 ages of the world there were also flying Lizards. 

 But m all these cases the mechanical principle is 

 the same, and there has been the same ingenious 

 adaptation of material and of force to the universal 

 laws of motion. 



On the earth and on the sea Man has attained 

 to powers of locomotion with which, in strength, 

 endurance, and in velocity, no animal movement 

 can compare. But the air is an element on which 

 he cannot travel — an ocean which he cannot navi- 

 gate. The birds of heaven are still his envy, and 

 on the paths they tread he cannot follow. As 

 yet ! for it is not certain that this exclusion is to 

 be perpetual. His failure has resulted quite as 

 much from his ignorance of natural laws, as from 

 his inability to meet the conditions which they 

 demand. All attempts to guide bodies buoyant 

 in the air must be fruitless. Balloons are mere 

 toys. No flying animal has ever been formed on 

 the principle of buoyancy. Birds, and Bats, and 

 Dragons, have been all immensely heavier than 

 the air, and their weight is one of the forces most 



