of Edinburgh , Session 1884-85. 
23 
but it specially requires the postulate (not, explicitly at least, alluded 
to in Maxwell’s paper), that every pair of particles , to whichever set 
or sets they may belong , shall be perfectly free to collide. It does 
not follow that the extension would hold in cases where there is 
any limitation to the freedom of collision, — such as is almost 
certainly the case when each particle of a gas is treated as a group 
of particles, or as a system with a considerably greater number of 
degrees of freedom than a free particle has. For some of the con- 
stituents of each particle may necessarily be so situated as never 
to encounter the corresponding constituents of another particle. 
In fact Boltzmann’s generalisation of Clerk-Maxwell’s Theorem, 
in which he asserts that ultimately the energy is equally shared 
among all the degrees of freedom, would seem to be at once confuted 
by the collisions of smooth spheres, where each has three degrees of 
(rotational) freedom to which no energy at all is communicated. 
6. Extraordinary Occurrence at House Ho. 7 York Place. 
( The following notice was sent to the General Secretary , from the 
Office of Messrs Hunter , Blair , and Coivan, IF.$.) 
An occurrence of an extraordinary nature took place in the 
kitchen of this house on Monday evening, the 8th inst. The 
kitchen is in the area, and whilst the office-keeper and his wife and 
servant girl were seated in front of the fire, suddenly, about twenty 
minutes past eight, a terrific rumbling sound was heard in the 
chimney. Fearing that something was about to topple about their 
ears, they all sprang aside, and no sooner had they done so than a 
large sheet of flame issued from the chimney, and without disturb- 
ing the ashes in the grate, or touching the grate itself, swept close 
past the office-keeper, who was standing nearest to the fire-place, 
and extinguished the gas. Upon the gas being relit, an extraordi- 
nary state of matters was revealed. The apartment was filled with 
smoke and dust, while the brick wall partition opposite the fire- 
place, and which would be 12 to 14 feet distant from it, was so 
greatly injured that had it not been for the shelving with which it 
was lined in front, and which held it together, it would have fallen 
right out. As it was it stood greatly off the perpendicular, and was 
