384 [Assembly 



very sensible warming effect on surrounding objects by its 

 freezing. 



In this way are the sudden changes of our climate moderated, 

 and to this physical fact do we owe the tolerable nature of our 

 winters and the duration of the vernal and autumnal seasons. 

 Without, sir, knowing anything of the physical geography of 

 Fort Ripley, I venture to assertthatif the thermometer falls there 

 to 36° below zero, there is not much water in the vicinity. That 

 the temperature of the valleys is higher than that of the hills in 

 winter must be attributed mostly to the fact that they contain so 

 much more water. 



But these facts entice us to take another step. Daily observa- 

 tion teaches us that changes of temperature are a fruitful source 

 of force. By heating rods of iron and allowing them to cool, a 

 power may be exerted that can only be measured by their tena- 

 city. If this operation could be performed with sufficient rapidi- 

 ty it might be made useful as a source of motion. When water 

 is used instead of iron it can be performed with sufficient rapidity, 

 and the expansion and contraction is much greater in amount. 

 Whatever medium is used, the origin of the force is in the change 

 of temperature So well has this come to be understood that the 

 price of a ton of coal depends on its heat producing, or in other 

 words its motor power. 



Now the converse of all this must be equally true. Changes of 

 temperature^ as they are going on aromid us daily, must he produced 

 by some motor power. What is that force? A perpetual motion 

 is continually going on around us, and by the laws of mechanics 

 it must be produced by the unceasing expenditure of power. 

 Does this power originate in the variations of temperature pro- 

 duced in different parts of the earth's surface by the heating ac- 

 tion of the sun 1 



In any machinery, when motion is to occur, the sum of the forces 

 must exceed the sum of the resistances. The more machinery 

 there is to be kept in motion, the greater become the resist- 

 ances. No machine can ever generate an ounce offeree, and the 

 more complicated are our contrivances to effect that phantasy of 



