112 CONCLUSION. 



to profit. But they are all either less understood, 

 and less open to the common observer than the 

 great principle of gravitation ; and so they may 

 be more advantageously noticed along with the 

 substances or the places in which their operations 

 are displayed. Those that perhaps demand the 

 first attention are they which, without any other 

 apparatus than the substances in which their effects 

 are seen, counteract or suspend the general in- 

 fluence of gravitation. 



