OF THE PROPERTIES OF MATTER. 17 



prising, to reflect upon the various and unthougbt of LECT. 

 methods and postures which we use to retain this posi- ^^^'^ 

 tion, or to recover it when it is lost. For this purpose 

 we bend our body forward when we rise from a chair, 

 or when we go up stairs : and for this purpose a man 

 leans forward when .he carries a burden on his back, 

 and backward when he carries it on his breast ; and to 

 the right or left side as he carries it on the opposite 

 side. A thousand more instances might be added." 



The quantity of matter in all bodies is in exact pro- 

 portion to their weights, bulk for bulk. Therefore, 

 heavy bodies are as much more dense or compact than 

 light bodies of the same bulk, as they exceed them in 

 weight. 



All bodies are full of pores, or spaces void of matter : All bodie 

 and in gold, which is the heaviest of all known bodies, 1 * 

 there is perhaps a greater quantity of space than of 

 matter. For the particles of heat and magnetism find an 

 easy passage through Che pores of gold ; and even water 

 itself has been forced through them. Besides, if we 

 consider how easily the rays of light pass through so 

 solid a body as glass, in all manner of directions, we 

 shall find reason to believe that bodies are much more 

 porous than is generally imagined." 



Note 12. Rope dancers and tumblers maintain a species of tottering 

 equilibrium by means of a lohg pole, which being rapidly shifted 

 in any required direction, retains the center of gravity of the whole 

 body within the toe. 



AWe 13. Without attempting to assert, with a distinguished philo- 

 sopher, that the whole of created nature may be compressed into the 

 size of a nut-shell ; we may at least pause for a moment to examine 

 the amazing porosity of some bodies, which would at first view ap- 

 pear perfectly dense and solid. Thus we find that glass, though of 

 great specific gravity, is readily penetrated by the sun's rays, when 

 conveyed to a focus by means of a burning glass ; and the light of a 

 candle may be seen through a thin leaf of gold. To further illus- 

 trate the matter, we may suppose a body to be so constructed as to 

 have as much vacuity as matter, and as such, half the body vacuous. 



C 



