NATURAL HISTORY. 161 



"No indeed. Oh yes, Uncle Philip, by 

 steam." 



"Ah, I mentioned paddles, boys, and a 

 steamboat is forced along by them." 

 " No ; Uncle Philip, we do not know." 

 " Well, I will tell you then of another way 

 in which I have no doubt a boat might be 

 made to move. If there were any contrivance 

 by which a large quantity of water could be 

 kept in the boat, and if this water were forced 

 out of tubes or holes at one end very violently, 

 it would push against the water in which the 

 boat was floating, and force her along. Some 

 years ago a plan was thought of to make a 

 steam engine throw the water out of the stern 

 of the boat, and thus to force her along ; and 

 before that, Dr. Franklin tried some schemes 

 for the same purpose, but they never suc- 

 ceeded. Now there is an insect which adopts 

 precisely this plan, and perhaps some of those 

 who thought of it got the notion from the 

 insect." 



"What insect is it, uncle Philip?" 

 " It is the grub of the dragon-fly. If you 

 catch one of these grubs and put it into a 

 saucer of water with some of the dead leaves 

 or sticks it had for a covering, you will see 

 o2 



