al other machines in the quantity of
product it will deliver for a given expenditure. The ground peat yielded
by it, must be moulded by hand, or by other machinery. This machine, we
understand, has been tried near Boston, and abandoned as uneconomical.

The machines we have described are by no means all that have been
proposed and patented. They include, however, so the author believes,
all that have been put into actual operation, at the date of this
writing, or that present important peculiarities of construction.

The account that has been given of them will serve to illustrate what
mechanism has accomplished hitherto in the manufacture of peat-fuel, and
may save the talent of the American inventor from wasting itself on what
is already in use, or having been tried, has been found wanting. At
present, very considerable attention is devoted to the subject.
Scarcely a week passes without placing one or more Peat-mill patents on
record. In this treatise our business is with what has been before the
public in a more or less practical way, and it would, therefore, be
useless to copy the specifications of new, and for the most part untried
patents, which can be found in the files of our mechanical Journals.

14. _Artificial Drying of Peat._

As we have seen, air-dry peat contains 20 to 30 and may easily contain
50 _per cent._ of water, and the best hot-made machine peat contains 15
_per cent._ When peat is used as fuel in ordinary furnaces, this water
must be evaporated, and in this process a large amount of heat is
consumed, as is well understood. It is calculated, that the temperature
which can be produced in perfectly burning full-dried peat, compares
with that developed in the combustion of peat containing water, as
follows:--

Pyrometric effect of perfectly dry peat 4000 deg. F.
" " peat with 30 _per cent._ of water 3240 deg. "
" " " 50 " " 2848 deg. "

But, furthermore, moist or air-dried peat does not burn in ordinary
furnaces, except with considerable waste, as is evident from the
smokiness of its flame. When air-dried peat is distilled in a retort, a
heavy yellow vapor escapes for some time after the distillation begins,
which, obviously, contains much inflammable matter, but which is so
mixed and diluted with steam that it will not burn at all, or but
imperfectly. It is obvious then, that when a high temperature is to be