114 
tabulated statement of Mr. Spence’s experiments showed a 
maximum breaking weight of about ocwt. and a minimum 
of about 3cwt. The mininum breaking weight was there- 
fore 40 per cent less than the maximum. With experi- 
ments showing such an excessive range in the breaking 
weight of bars, which from the care taken in their produc- 
tion ought presumably to have been homogeneous in quality, 
it was very unsafe to rely upon a resulting difference of 
only 3 per cent derived from separately adding the breaking 
weights of each set together and comparing the gross results. 
The iron used was obviously of an inferior quality and quite 
unsuitable for the purpose of reliable experiments. 
MICROSCOPICAL AND NATURAL HISTORY SECTION. 
January 30th, 1871- 
Joseph Baxendell, F.R.A.S., President of the Section, in 
the Chair. 
Mr. Boyd Dawkins, F.R.S., exhibited sections of the 
calcareous nodules from the Gannister coals of lower coal 
measures of Oldham, in which the intimate structure of the 
various forms of carboniferous vegetation were admirably 
preserved. He also brought before the notice of the Society 
a series of microscopical sections of coal prepared by Mi\ 
Newton, in which the spores and sporangia present in all 
bituminous coals, and from which a large percentage of their 
