LOVE S MEmiE. 57 



selves, and jou easily may. Some of jou, perhaps, knew, 

 in your time, better than the doctor, how a kite stopped ; 

 but I do not doubt that a great many of you also know, 

 now, what is much more to the purpose, how a ship gets 

 along. I will take the simplest, the most natural, the most 

 beautiful of sails,— the lateen sail of the Mediterranean. 



6Q. I draw it rudely in outline, as it would be set for a 

 side-wind on the boat you probably know best,— the boat 



faces of the wings ; (5th), to the ever-varying power with which the icings 

 are urged^ this being- greatest at the beginning of the down-stroke, and 

 least at the end of the up one ; (6th), to the contraction of the volun- 

 tary muscles and elastic ligaments, and to the effect produced by the 

 various inclined siirfaces formed by the wings during their oscillations • 

 (7th), to the iceight of the bird—height itself, when acting upon wings, 

 becoming a propelling power, and so contributing to horizontal mo" 

 tion." 



I will collect these seven reasons for the forward motion, in the gist 

 of them, which I have marked by italics, that the reader may better 

 judge of their collective value. The bird is carried forward, according 

 to Dr. Pettigrew — 



1. Because its wings leap forward. 



2. Because its body has a tendency to swing forward. 



3. Because the wings are screws so constructed as to screw upwards 



and onwards any body suspended from them. 



4. Because the air reacts on the under surfaces of the wings. 



5. Because the wings are urged with ever- varying power. 



6. Because the voluntary muscles contract. 



7. Because the bird is heavy. 



What must be the general conditions of modern science, when it 

 is possible for a man of great experimental knowledge and prac- 

 tical ingenuity, to publish nonsense such as this, becoming, to all in- 

 tents and purposes, insane, in the passion of his endeavour to overthrow 

 the statements of his rival ? Had he merely taken patience to consult 

 any elementary scholar in dynamics, he would have been enabled to 

 understand his own machines, and develope, with credit to himself, 

 what had been rightly judged or noticed by others. * 



