EUCALYPTUS TREES. 49 
of charcoal: It may be made in mounds, caverns, or 
ovens. The method most frequently adopted is that 
in mounds or meilers, and to this I may devote a few 
explanatory words, as not every one in this hall may 
be conversant with the process; for, simple as the 
process does appear, it is, after all, not performable 
without some skill, if coal of a superior quality is to 
be the result. The wood is closely packed around a 
central post in regular form, the pieces either all hor- 
izontally, or, oftener, the lower vertically. Only such 
wood should be used as is unfit for timber; it must, 
however, be of one kind only, or of such various sorts 
as require the same degree of heat for being converted 
into a perfect coal. It must be sound and almost air- 
dry. A loamy sand-soil forms the best base for a 
mound ; and this soil requires to be broken up, lev- 
eled and pressed, also dried by branchlets being burnt 
on the ground. The form of the mound or meiler is 
usually hemispherical, and support is given to this 
mound in the manner indicated in the sketch here 
presented, the outer support consisting of short logs 
of wood. 
The inner part of the cover is formed of sods of 
grass, branchlets, rushes, and similar substances; over 
this is placed the outer portion of the cover, consist- 
ing of moist forest-soil, particularly fresh humus. 
The united covering must permit the vapors of the 
glowing meiler to escape. Shelter against wind is 
absolutely requisite ; the operation of burning coal can 
therefore be well performed only in still air. The 
ignition commences from an opening left purposely, 
either at the base or, less frequently, at the summit 
of the structure, but either opening is closed again 
ae 
