4 BULLETIN 102, PABT 1, UNITED STATES NATIONAL MUSEUM. 
materials, and Europe would presumably become more and more the 
source for refinement of industrial procedure and the clearing house 
of world trade. 
For additional comparison, a cube showing the relative impor- 
tance of the coal resources of the United States is given place 
in the series. Noting the share of the world’s supply thus repre- 
sented, a conception of the industrial potentialities of this country 
opens up, reaching beyond the grasp of the imagination. Yet en- 
trusted with a great share of what the whole world has to rely upon 
for material support in the encompassing progress of civilization, 
the yield from this vast heritage has not been made to respond ade- 
quately even to current purely domestic needs. True, it is ener- 
gizing a vast industrial development, and thus far at least it has met 
the fuel requirements of the American home ; but these are only two 
of its three functions, and as a matter of fact their ends are attained 
through the actual normal employment of only about two-thirds of 
the mass representing coal. The other third embodies a veritable 
treasure house of products catering to needs of civilized man, and the 
spectacle of the United States, with its dominating bulk of poten- 
tiality, helplessly pleading with European countries to render coal- 
product assistance despite the overwhelming nature of their own trou- 
bles, is fresh in the minds of all. It is not a spectacle to be proud of, 
but it is one well worth contemplating in the light of an object 
lesson. 
Growing out of the composition inherent in the nature of coal, the 
subject may be approached to best advantage along the lines of 
origin. Taking the averages of composition representative of each 
coal type, it will be found that these are capable of an arrangement 
wherein the various familiar classes of coal such as lignite and 
anthracite appear as so many stages in a process of chemical evolu- 
tion. Such an arrangement is represented in graphic form on plate 
1 and points significantly to vegetal accumulations as being the 
source of coal. The further confirmation of the same, the actual 
fossil outlines of vegetal remains found in diminishing fullness of 
preservation from peat upward through the successive stages to 
anthracite, are conclusive. In fact, the fossil forms of vegetation 
are sufficient to enable the imagination to supply what is lacking 
and depict original conditions with reasonable assurance of accu- 
racy. This has been done by Unger, among others, and his resto- 
ration is reproduced on plate 2. 
It is to be observed to-day that the thickness of the vegetable 
mold blanket bears a direct relationship to the degree of moistness. 
This is partly owing to the increased luxuriance of growth under 
such conditions and partly due to the protective influence the water 
exercises against the oxidizing attack of the air; and the combined 
