§ Sir I. Horobin
"Large" coal is coal which will not pass through a screen with round holes generally 2 in. in diameter, though they may vary in different screens.
"Small" coal is coal generally with a top size of ½ in. although this can vary in different places up to 1½ in.; it includes everything down to dust.
"Graded" or "Sized" coals lie between the other two categories. That is to say, generally speaking, they range from ½ in. to 2 in. There are however variations in both the lower and upper limits, the former in some cases being as low as ⅛ in. and the latter as high as 2¼ in. Doubles, singles, beans, peas and grains come within the category of "graded".64W
In 1957 total commercial disposals of home-produced coal—excluding coal used at collieries or supplied to miners—were:
(million tons) Small 97 Large 49 Graded 43 Unscreened (mostly gas and coking coals) 12 Anthracite 4 Total 205