Concrete Matter from Atomic Origins. 399 
per second. The centreward acceleration of all the others 
will be in simple proportion to their distances from the centre 
of the assemblage. This is easily seen by remarking that, 
according to Newtonian principles, the resultant force on 
each cube is the same as if all the cubes at less distances than 
its own from the centre were condensed in a point there, and 
all the cubes at greater distances than its own were annulled 
Hence as long as the cubes all fall freely inwards their dis- 
tribution remains uniform, and their boundary spherical. 
§ 4. Hence the cubes, if all similarly oriented as in 
§ 2, will, at one instant of time, all come into contact, each 
with all its six nearest neighbours : and for an instant they 
will be fitted together making a great globe of the same size 
as the Earth, but with angular projections at the spherical 
boundary according to their cubic arrangement. All the 
parts of this composite globe are, at the instant of first contact, 
moving inwards at speeds simply proportional to their dis- 
tances from the centre. If the cubes were perfectly elastic, 
they would rebound outwards with velocities equal to those 
they had at the instant of first contact ; and a periodic 
falling inwards and rebounding outwards would follow ; 
which would continue for ever, if there were no ether to resist 
this gigantic oscillatory movement. But what would be done 
by cubes of real matter, with its true molecular constitution 
and imperfect elasticity, in and after such a prodigious, purely 
pressural, collision, is not a subject for profitable conjecture. 
§ 5. Let now the cubes be placed initially at rest, with 
their centres arranged as in § 2, but with orientations given 
at random, and let them fall freely. Contacts between some 
neighbours will begin to occur when the shortest distances 
between centres are equal to 3% or 1*732, metres, being the 
length of the body diagonal of each cube. At this instant 
the whole assemblage occupies 3% or 5*196, times the Earth's 
bulk : and the average density is somewhat greater than the 
density of water. 
§ 6. The velocity of the outermost cubes at the instant of 
impact, in the case of the similar orientations of § 2, is 11,175 
metres per second. If the cubes were reduced to infinitely 
small material points at their centres, and so could continue 
to fall freely to the centre of the sphere, they would all reach 
that point in *897 of a year from the time of our ideally 
assumed initial state of rest. As the material points fall 
towards the centre of the sphere, the mean density of the 
assemblage continuously increases. The following table 
shows the number of minutes during which the system must 
2E 2 
