24 The Book of Bugs. 



the window pane by the pressure of the atmosphere, 

 which is fifteen pounds to the square inch. 



' Oh, sir ! ' exclaimed Willie I think his name was 

 Willie ; it ought to have been ; he was a good little boy 

 and gave his dinner to the blind beggar and was kind to 

 all ; he even played in public with his little sister, and a 

 boy that will do that needs watching- ' oh, sir ! ' ex- 

 claimed Willie,, ' that is like the leather suckers with 

 which the boys play. They wet the leather, to the center 

 of which a stout string is attached. Then they stamp 

 it upon a paving stone, and it adheres to it so that it is 

 possible to lift up the paving stone. 11 



" Exactly so," said the wise Uncle Harry. 



That happens to be about the case with the fly's foot, 

 but Uncle Harry was quite in the wrong in pointing out 

 the air pump in the fly's foot, for the reason that there is 

 no air pump there, and even if there were the atmospheric 

 pressure would not be enough on the surface of the fly's 

 feet to hold up more than half his weight. I am glad, 

 though, that little Willie mentioned the leather suckers, 

 because ever since then when anybody has begun to ex- 

 plain anything by saying, " It works on the principle of 

 those leather suckers the boys play with," I know right 

 off what he means, which I should not if I had never read 

 McGuffey's Fourth Reader, because in all my life I have 

 never seen one living human boy play with any such a 

 toy. Others may have experienced that pleasure, but it 

 has been denied me. 



It was a French abbe with the Thackerayan name of 

 De la Plouche who first suggested that flies gummed their 

 feet to the wall with a viscid liquid. I am glad to state 

 that this man was laughed at all over the world, and that 

 the air-pump defenders proved conclusively that it was 

 all nonsense, because, don't you see, if a fly has wet feet 



