548 Our Surroundings 



Rome, propelled largely by oars. Later, sails were added and in 

 time ships were driven entirely by wind. 



When Fulton, in 1807, adapted the steam engine to driving a 

 boat regardless of wind and tide, a new era in water transporta- 

 tion began. By degrees ships grew in size and strength, paddle- 

 wheels gave way to propellers, and steam turbines took the place 

 of old-time engines. The enormous steamship of today, more than 

 ten times as large as Columbus' largest vessel and many times 

 greater in carrying capacity, is a striking product of centuries of 

 progress in many sciences. 



Not only did Science make possible the great ships of today, 

 but it also gave the means to keep them accurately on their 

 courses. For centuries the sun and stars had been the mariners' 

 only guides. Then Science gave them the compass to tell direction 

 and the astrolabe to determine latitude. With these instruments 

 Science guided Columbus to America. Today the compass has 

 been made far more reliable, the sextant gives latitude accurately, 

 the chronometer helps determine longtitude, and the log indicates 

 speed. Buoys and lighthouses warn ships from shoals and reefs 

 and guide them into harbors. Radio keeps ships in contact with 

 land and with other ships. So Science has made travel by sea far 

 more rapid, far more comfortable, and far safer than ever before. 



Science and Communication. Messages of early times were 

 transmitted by word of mouth. With the invention of writing, 

 communication was extended, messages being sent by runners or 

 horsemen. Later, as modern civilization developed and corre- 

 spondence became common, mail routes were established, letters 

 being carried by post riders and stage coaches. These in turn 

 gave way to railway mail transportation until today we have mail 

 trains equipped to take on and deliver mail without stopping and 

 to sort and sack mail enroute. Science, too, is making possible 

 even more rapid transmission of written messages by the use of 

 the airplane. Air mail service is already well established and is 

 being rapidly extended. It carries our letters much faster than 

 do the fastest trains. 



Previous to 1844 the message sent by train represented the 

 most rapid form of communication. In that year, however, 



