CHAPTER II. 



FORCE. 



23. Matter is constantly changing its form 

 B^ntlych^g- 9'iid place. The most solid substance will in 

 ^^' time wear away. The air about us is never per- 



fectly still. We see water sometimes as ice, sometimes as 

 a liquid, sometimes as a vapor, in steam or clouds. The 

 earth moves sixty-eight thousand miles every hour. An 

 animal or vegetable dies, decays, and its form vanishes 

 from our sight. 

 „ ^ , 24. As the cause of aU the changes observed 



To what cansa • ^ , o 



do we attribute to take placc in the material world, we admit 



the changes ob- , ^ • n i • i 



served in mat- the cxistencc of Certain forces, or agents, which 



govern and control all matter, 

 whatia 25. Force is whatever produces, or opposes 



'"^'^ motion in matter. 



What is Mo- 26. Mobility, or the susceptibility of mo- 

 biuty? iJQjj^ is that property whereby a body admits 

 of change of place. 



What are the 2*^- "^^^ *^^ great forccs, or agents in nature, 

 StMoT*^*"* those which produce, or are the cause of all the 

 changes which take place in matter, may be 

 .enumerated as follows : Internal, or Molecular Forces, 

 the Attraction of Gtravitation, Heat, Light, the At- 

 tractive and Repulsive Forces of Magnetism and Elec- 

 tricity, and, finally, a force or power which only exists 

 in living animals and plants, which is called, Vital Force. 



Concerning the real nature of these forces, we are entirely 



What do we ignorant. "We suppose, or say, they exist, because we see 



know of the ° . „ ^ , ■' ^ . 



nature of their enects upon matter. In the present state of science, it i3 



these forces? impossible to know whether they are merely properties of 

 matter, or whether they are forms of matter itself, existing in an 

 exceedingly minute, subtile condition, without weight, and diflFused through- 

 out the whole universe. The general opinion, however, among scientific men. 



