( 73 ) 
that way T-and thus the two pai?$ of 
planes are marked with ftreaks: The 
third pair of planes receiveth its ftreaks 
from that part of the Fluid, which palT- 
eth between the Cube and the Fluid, 
refleding from the hafe oi the Cube. 
4, As to the Perfection: ot the Figure: 
For among Chryflals there is very hardly 
one to be found, in whofc lhape there is 
not fomething defeCj;ive,but in the Cubes 
of the iMarcaffes there is feldom any 
thing' wanting. Nor is it hard to give a 
I'eaibn hereof* for fince that in Chryftals 
all the folid Angles, (the extreme excep¬ 
ted j are obtule, and that to each plane 
of them the Chryftallin matter is joyned 
a part by it felf, the faid plane becomes 
fo much the lefs, whilft the neighbour¬ 
ing planes alter the figure. l^ut in the 
Cubes of a Marcafite, feeing that all the 
folid angles ^re right angles, although 
new matter be added to one plane alone, 
that plane ever keeps the fame magni¬ 
tude, the neighbouring planes not chan¬ 
ging the figure. 
Many other things areobferv’d in the 
Cubes of Marcafitesj as. Cubes inclu¬ 
ded in Cubes, the Mavccof the Marca- 
^ . 
