5 How Engines Work. 



same time the exhaust-pipe outlet is closed above 

 and opened below, so that by opening and shut- 

 ting these outlets and inlets the piston is kept 

 going up and down with power enough to 

 force a large boat through the water, or a loco- 

 motive with many cars behind it along a rail- 

 road. 



A Steamship and Sailing- Vessels on the Ocean. 



1 6. Men have also made steamers whose out- 

 side is entirely of iron. One of these, the Great 

 Eastern, is like a small village in the number of 

 persons it can carry. 



17. War-steamers of iron have been built 



