THE STEAMBOAT 289 



less space. (3) They are more economical at high speeds. 

 (4) They are more easily tended and require fewer repairs. 



DEMONSTRATION 21 



Purpose. To make a simple steam turbine. 



Apparatus. Flask, rubber stopper with one hole, glass 

 tubing, toy windmill. 



Directions, i. To make a toy windmill, take a piece of 

 paper about 6 inches square and cut from each corner in- 

 ward nearly to the center. Fold over every other point. Pass 

 a pin through these four points, through the center of the paper, 

 and then into a wooden handle. 



2. Heat a piece of glass tubing and draw it out nearly to a 

 point. Break it off, leaving a very small hole. Put this tube 

 in the hole of the rubber stopper and then insert the stopper 

 in a flask so that the small point is uppermost. Fill the flask a 

 third full of water. Heat the flask till the water boils vigorously. 

 Then hold the windmill over the glass tube where the steam is 

 escaping. 



Change in a century. About one hundred years after 

 the Clermont had made its first trip at the rate of 5 miles an 

 hour, another boat, a yacht called the Arrow, traveled a 

 mile over the same course in i minute and 3 2 seconds, which 

 is at the rate of 46 miles an hour. From 5 miles an hour to 

 46 miles an hour represents the progress made in one hun- 

 dred years. 



How vessels are guided. Compass. In the earliest times 

 men did not dare to venture far from land but steered by land- 

 marks, by the sun, and perhaps by the flight of birds, and on 

 clear nights by the stars. The compass was first used as a 

 guide in steering ships between noo and 1200 A.D. In its 

 first form it was a needle in a straw floating on water. About 

 1360 the needle was mounted on a pivot and inclosed in a 

 box as it is now used. A compass is a magnet mounted so 

 that it can turn easily, and it always takes a north and south 

 u 



