1 9^91 
will be reciproGally proportional to their correfpondent 
numbers, e. g. a cubic foot of water is to a cubic foot 
of Alabafter in gravity as looo to 1872 ^ but a pound 
weight of water, is to a pound weight Alabafter in mag- 
nitude, as 1872 to 1000. So that knowing by the for- 
mer table, the weight of a cubic foot of water, and by 
this, the proportion in gravity betwixt water and Alaba- 
fter J we may by the rule of 3 find the weight of a cubic 
foot of Alabafter, and so of any other of thefe bodys 5 or 
we may know their magnitude by knowing their gravity. 
So that an irregular piece or quantity of thefe bodys be- 
ing offered, 'tis but weighing them, and we may know 
their juft magnitude without farther trouble^ 
P 2 
