2o8 THE STRUCTURE AND LIFE OF BIRDS char 



Great Depressor and the Elevator from the bone while 

 leaving their tendons attached to the humerus, 

 then pull them and watch the result. Much that 

 otherwise must be obscure then becomes perfectly 

 clear. Not the least interesting point is the way in 

 which the Elevator, being attached where it is, raises 

 the front or praeaxial margin of the wing, so that in 

 attaining its position for a fresh stroke it turns the 

 edge to the air and meets with little resistance. These 

 two muscles can also be worked at the same time, the 

 one antagonising the other ; the Depressor lowering 

 the wing to the horizontal, while the Elevator holds 

 the praeaxial margin fast, so that the hinder part 

 cannot be tilted up. A bird sets his wings thus when 

 he wishes to halt. A movement that looks perfectly 

 simple may be due to the combined action of a 

 number of muscles. 



The Spreading of the Wing. 



It is a strange thing that in these days when it is 

 boasted that machines can be made to do most things 

 that a man can do, that sailors should still have to 

 run up the rigging, be the weather foul or fair, and 

 straddle across the yards in order to furl or set 

 the sails. It would not seem to be beyond human 

 ingenuity to devise machinery by the aid of which 

 this work should be managed from the deck. Some 

 progress towards this has, I believe, been made. In 

 the bird we find such machinery brought to great 

 perfection. Instead of men we have muscles, and by 

 the machinery of tendons and ligaments these muscles, 



