330 Review of Prof. Johnson’s Report on American Coals. 
the daily and other observations of facts as they occurred and 
were originally recorded, with the formule by which the deduc- 
tions obtained from these facts were worked out. He who has 
any doubt of the correctness of these, has thus before him all the 
materials necessary to make his own calculations and deductions. 
There is no begging of confidence, no dogmatic assumption of 
superior knowledge, no mere enunciation of ex cathedra opinions. 
Table CC, exhibiting a synoptical view of the character and 
efficiency of the several coals, and table CCI, showing the ranks 
of the various coals according to the several practical characters, 
may be considered as the summation of the relation and useful 
properties of these different kinds of fuel, exhibited in the most 
distinct practical point of view. We shall present the entire of 
the former table, because it contains valuable information, to 
which those may refer who have not the Report. 
Table CCI is so arranged as to show the rank of the coals, 
Ist, as to relative weight; 2d, rapidity of ignition; 3d, complete- 
ness of combustion; 4th, evaporative power under equal weights ; 
5th, evaporative power under equal bulks ; 6th, evaporative power 
of combustible matter; 7th, freedom from waste in burning; 
8th, freedom from tendency to clinker; 9th, maximum evapora- 
tive power under given bulks; 10th, maximum rapidity of 
evaporation. 
These tables show that no one coal presents all the qualities 
necessary to place it at the head of every rank, and that therefore 
a judicious selection is necessary to secure such as may be re- 
quired for peculiar application. 
