90 GLIMPSES OF NATURE. 



of names. Now, this word " force " and the term 

 " energy " are legitimate and useful words enough in 

 science ; and I question whether we can advance any 

 distance at all in " the primrose way " of intellectual 

 culture without knowing something about them. By 

 " energy " we mean the " power of doing work ; " and 

 " force " is simply the equivalent of energy. 



If I might put it practically, " force " is energy in 

 action. You possess in your biceps muscle a store of 

 energy, derived, of course, from your food. You buy 

 so much energy when you pay the bill for your ton 

 of coals ; and you also acquire energy in the shape 

 of the mutton-chop you anticipate having for lunch. 

 When you raise your forearm by means of your 

 biceps you liberate the stored-up energy of the 

 muscle, and illustrate muscular force of power. When 

 you burn your coal in the grate, the heat you obtain 

 (the chief part of it, however, goes up the chimney) 

 is liberated energy again, just as the motion of the 

 steam-engine, which you might feed with your coals, 

 is a part-result of the conversion of the locked-up 

 energy of the Carboniferous plants into force. When 

 you go cycling between lunch and dinner, you may 

 assume that the energy which the grass-eating sheep 

 stored up in the mutton-chop is being liberated in 

 the force with which you propel yourself along the 

 highway. I might add that, in the shape of the 

 carbonic-acid gas and other waste matters you give 

 out with each breath, you are giving back to the grass 

 somewhat of the material it (through the sheep) gave 

 to you. This is an illustration of the revenons a nos 

 montons idea, which is both apt and forcible, because 

 it is so true. 



In the wood to-day, under the influence of the sun- 



