AIR AND WATER AS SERVANTS OF MAN 1 19 



When the boat is driven by a propeller the force with which 

 the propeller blades strike the water is decomposed, one element 

 serving to drive the boat ahead just as the propeller of the aero- 

 plane carries it through the air (p. 99). At present the record 

 for speed boats is held by " Miss America II." Her official record 

 is 80.56 miles per hour, made in 1921. Nothing like this speed 

 is maintained in commercial craft. Still the best of the trans- 

 atlantic liners now make 23 to 25 knots per hour, and the latest 

 battleships make 35, while destroyers run at still higher speeds. 



We do not know at all who first devised the boat, and we 

 can only guess the steps by which its discovery progressed. Still 

 the very primitive types of boats yet in use help us to formulate 

 guesses that are probably nearly correct. As far back as history 

 goes sailboats were used and these, quite pretentious ones. On 

 an old vase, now in the British Museum, which was found in an 

 Egyptian tomb is the relief of a sailboat. This boat was also 

 manned by many oarsmen, for on the Nile wind is not always a 

 dependable motor power. This vase is one of the oldest relics 

 of ancient Egyptian civilization that has come to light, probably 

 3,000 years old or more. In the oldest code of laws yet dis- 

 covered, laws written on the clay tablets of the ancient peoples in 

 the Tigris and Euphrates valleys, there were strict regulations 

 in regard to the course of vessels and their movements when 

 passing each other or in coming to port. Marble models of 

 boats from this same time, probably votive offerings, show their 

 general shape and structure, the holes for the masts and the 

 rigging being visible still, though masts and shrouds are gone to 

 dust. 



Probably boats have been devised and used independently 

 by various peoples in different parts of the world, and we shall 

 never know exactly by whom the various types of primitive craft 

 have been invented. One can readily imagine, however, how 

 the savage, desirous of crossing a stream, straddled a floating 

 log and trusted to the current or the wind to land him on the other 

 shore. He must soon have found that his arrival at his destina- 



