COMMUNICATED MOTION. 3J 



the waters of the sea, but upon more solid bodies, 

 such as trees and buildings. 



When a body has been in motion for some time, 

 even a loose thing upon it has no tendency to fall 

 off, unless there be a jolt which causes a change either 

 in the rate or the direction of the motion. As when 

 a boat is gliding uniformly and smoothly along, a 

 vessel of water on board may be as still as a lake ; 

 but if the boat pitch in one way, the water is apt 

 to splash over the other side of the vessel. So also 

 if it get suddenly into rapid motion, a careless per- 

 son standing on the stern will be very apt to tumble 

 into the water behind ; and if, when in rapid motion, 

 it suddenly stop, a careless person standing in the 

 bow will be apt to fall forward into the water. In 

 like manner, when a horse turns or starts to a side 

 unexpectedly, an inexperienced rider is very apt to 

 be jerked off the other way; these and many other 

 results of a similar kind, take place, because some 

 time is required to communicate the change of mo- 

 tion or direction from the one body to the other. 

 Just for the same reason, if the earth were to get 

 a velocity in its orbit much greater than it has at 

 present, the solid part of it would roll on, and leave 

 the atmosphere, the water, and the loose substances 

 behind ; and if it were to be suddenly stopt, those 

 matters would be projected forward. In like man- 

 ner, if the rotatory motion eastward were to be greatly 

 augmented, the air and water would dash in hurri- 

 cane and flood against the east sides of the continents 

 and islands ; and if the motion were to be suddenly 



