183

General Description.

It appears therefore, from these trials, that halfa bushel of coal, with lime, generates very nearlythe same quantity of steam as one bushel and ahalf without the lime. This however may bebetter illustrated by the following statement ofthe comparative expense.

s. d.

First experiment .—Half a bushel of coal. O 7

One bushel and a half of chalk .. 0 2

0 9

Second experiment .—One bushel and a half of coal.. 19

In the first experiment the lime produced bythis species of burning may fairly be averaged atnine pence, so that, compared with the presentmode, the saving on evaporating thirty gallons ofwater by means of the chalk, where a ready modeof disposing of the lime can be devised, is nearlyIs. 9 d. or the total expense of the fuel.

Mr. Parkes employs an air-valve, somewhat si-milar to that of Mr. Roberton, though placed in adifferent part of the furnace; and either of theseplans, if properly managed by the fire-man, wouldfully answer the end for which they were intended;but unfortunately this requires a degree of mecha-nical skill and attention seldom found in this class ofpersons; and though the nuisance may be abatedfor a short time, or while the engine is under theimmediate superintendance of the engineer, novery permanent benefit has yet been found to ac-crue. To remedy this, Mr. Brunton proposes toemploy a mechanical apparatus completely beyond