230 
books and papers (indicating a wonderful progress in this 
beautiful and fascinating science), have assisted tbe mining 
engineer to an incalculable extent. 
As a basis upon which to build the argument of my paper, 
I have selected the Middleton Main Seam of Coal as being 
one of the most important and substantial seams in the whole 
series, considering the area it occupies and the average 
thickness it attains to (nearly 4 ft.), in the Yorkshire Coal 
Field. 
My illustrations represent the two generaUy-recognised 
systems of working the above seam; and the figures and 
deductions that I may hereafter make, are taken from 
personal knowledge of the results actually obtained from the 
working of the above seam under both systems in the same 
district. 
For simplicity in discussion, and as comprising all we 
require for the purpose of this paper, I shall condense 
the various modes of working Coal in Yorkshire into two 
systems, viz., " pillar and stall " and " longwall " with 
pack-gates, for all the recognised modes of getting Coal are 
but modifications of either one or the other of these two 
systems. 
I shall first refer to " pillar and stall," and, here in pas- 
sing, it may be interesting to mention that the most primitive 
mode of getting Coal seems to have been associated with this 
idea. Even so far back as the Eoman occupation in this 
country, at any rate, it is recorded on incontestable evidence, 
during the Anglo-Saxon period of about the 9th century,, 
where evidence has been collected of the Coal having been 
obtained in this rude form, better described as consisting 
of getting a piece of Coal and leaving a piece alternately. 
At the same time, in justice to the Eomans, who were an ex- 
ceedingly practical and skilful race, we must remember that 
they were limited to "basset" workings, and, consequently. 
