292 SCIENCE OF HOME AND COMMUNITY 



in a north and south plane regardless of any motion of the 

 ship. The top is covered with glass, and on this is a dial 

 showing the points of the compass. Other dials may be 

 placed in any part of the ship and by means of electrical 

 connections with the gyroscope the true readings are indi- 

 cated on these dials. 



LABORATORY EXERCISE 29 



Purpose. To see how a gyroscope works. 



Apparatus. Toy gyroscope. 



Directions. Set the gyroscope spinning by means of a string. 

 Try placing the gyroscope in a great many positions, as on the 

 edge of a tumbler, on a string, on the tip of a pencil, on the end 

 of the finger with the axis horizontal. How could this be used 

 to guide vessels ? 



Protection from accidents. In order to assure the safety 

 of the large ocean ships, they are provided with a number 

 of separate water-tight compartments, so that if by accident 

 water should enter one, it cannot flood the others. As a 

 protection against icebergs, an instrument called a frigidom- 

 eter is used. This consists of a special thermometer placed 

 near the forward end of the ship, in a vessel through which 

 sea water passes. The lowering of the temperature may 

 indicate the presence of icebergs. This thermometer is 

 connected with an indicator on the bridge. This can be 

 so set that when a certain temperature is registered by the 

 thermometer, an electric gong rings and a red light shows 

 as a warning to the one on watch. Protection from fire is 

 assured by the use of steel instead of wood in the construc- 

 tion of the ship. 



Protection from rocks. Protection from dangerous rocks 

 and coasts is assured by signals conveyed under water. 

 A bell is submerged under water over the dangerous rocks 

 and the strokes are controlled from a shore station or from 

 a lightship by means of electricity or compressed air. The 



