thepobt I 0 o m6 C b /. £he TfVi eig ^ equal P Iane an 8’ les ai 
'^“£t irt bj the """ of fo " *- 
This form has 24 edges, each equal to the edo-e CU, 24 
each equal to the edge and 24 4 ea ch equal to o% ‘ " 
pn r 16 ^S 1 ® 8 of th . e triangular faces of this form differ for 
each particular species of the six-faced octahedron. 
. 7/ W mS - ttexalas-ctctaliedron, hexoctahedron . tetraJwntcc - 
sssajBr" *w **&£> 
, 19- i ? : '. liese 1 s ? ven forms, grouped together on Plate I 
eS’uKf ™'‘ oa i- ,r“?' ““ “* »«b,c. 
c ffXnT ", ° r the ° At ’ *“■ « p-JK e 
4 29^p£r,f , rir,“" bi r d “>■ «j*“. 
m riate iy.*, the forms to whicll tIie f 
parallel, except in the case of what are called twin crystals 
Therftm^hre^^l ^ regard to ea °h°tto! 
other but^Lv ! , ° nlj ! h - 13 natural relationship to each 
..«,Sr£r" rei * ii "> " , « i * 
to 2 each°othef t 4 f ° mS P resent no relationship 
li i C V ? 1 e * Plate sll ows them connected together 
by beautiful geometrical laws. together 
can eJ! PIatS lb W6 f ee . that . eacl1 of the six other forms 
the cube^ 0116 01 * 16m b ® lnscnbed > as geometers term it, in 
A*’. f lafc ® f/o sb ows the cube having each of its faces 
divided into eight equal triangles, by joining the oLosite 
angles of each square by two diagonals suclfas 0,0^0 0 
ZohZ&^D 6 T tre °\ the f 4 and b 7 *™ otto HnS; 
j) JD of VliP prl 5J 111 ® 1} an ^ j° inm g the centres 
“ a c - D - lhe “” te “ « f lhs 
cube lg and wf Four 'f aced ™be inscribed in the 
faced cube G G t r t “i B 2 ld a “ gIeS ° f tie ^enty-four 
of the C ircumscribing'cube.° UCb “ C6ntreS ° f the six faces 
of fff soM anrfS '*Po inscribed in the cube, six 
S i X faces of the g ciriSibfng^ube ^ ^ ° f the 
the c g ube, L six h o e f STc tlZtfc < T£"r* £ 
c trfj lh T S“r f * i | «—& iti Str*"* ke 
J.]g. 12. lhe Rhombic dodecahedron inscribed in the cube 
