No. 3.] ATOMS AND MOLECULES. 577 
where other atoms can join, in which case, if all were vibrating 
similarly, there might be a conjunction, as shown in Fig. 4, —an 
atom at each one of the nodes; but 
such an arrangement in one plane would 
not be a stable arrangement. The point | 
of attachment of any one might be con- 
sidered as a kind of hinge, allowing a 
swing to and fro. Imagine two oppo- 
site ones, as 2 and 4, to swing upwards , 
so as to touch each other. If these ‘ 
be vibrating, their points of contact 
will be nodes. They will, therefore, 
cohere by another bond, and such an atomic arrangement will 
be a stable one. If the rings have equal dimensions, an edge 
view would show them as an equilateral triangle with nodes at 
the apices, Fig. 5. We might call such a combination a mole- 
cule, and say it was held together by chemism. Each molecule 
thus constituted must have a mechanical fe/d, which will be the 
resultant of all the atomic fields that compose it ; and indeed this 
will be true for such molecules of every degree of complexity. 
Molecules having similar fields fit together for obvious mechani- 
cal reasons, and cohere because they are pressed together by 
the medium they vibrate in. If similar triangular forms to the 
one above unite, they may form hexagonal prisms, as Fig. 6 
shows, in cross-section, and such as is the crystalline forms 
assumed by water, silica, and some other minerals having three 
atoms in the molecule. 
Fic. 5 Fic. 6. 
Now let 2, 3, 4, and 5 of Fig. 4 swing upwards; they too will 
touch each other at their sides and at nodes, so as to form a 
stable figure held by eight bonds, —an atomic box without a 
lid, — yet having four nodes on the open end to which another 
