70 ANNUAL OF SCIENTIFIC DISCOVERY. 



duced beneath the burning red hot coal, so that its pitch, in rising as vapor, 

 must pass among the parts of the burning mass, it will be partly resolved into 

 inflammable coal gas, and will itself burn, and inflame whatever else it touches. 

 Persons often amuse themselves by pushing a piece of fresh coal into the 

 center of the fire in this way, and then observing the blaze of the newly -formed 

 gas. 



Various attempts, beginning perhaps with Dr. Franklin, have been made 

 to get rid altogether of smoke : one of the most recent of which was made by 

 a London manufacturer, Mr. Cutler. He placed a box filled with coal under 

 the lire, with its open mouth occupying the place of the removed bottom bars 

 of the grate, and in the box was a movable bottom, supporting the coal, by 

 raising which it was lifted gradually into the grate to be consumed. The 

 apparatus for lifting, however, was complicated, and liable to get out of order, 

 which with other reasons, caused the stove to be little used. The movable 

 bottom rested on a cross-bar of iron, which in moving was guided by slits in 

 the side of the coal box, and was lifted by chains at each end, drawn up by 

 a windlass. Dr. Arnott then described a new fire grate somewhat on the 

 above-noticed principle but more simple. The charge of coal for the day is 

 placed in a box immediately beneath the grate, and is borne upward as 

 wanted, by a piston in the box, which is raised by the poker used as a lever, 

 and as readily as the wick of an argand lamp is raised by its screw ; the fire 

 is thus under command, as to its intensity, almost as completely as the flame 

 of a lamp. There are notches in the piston-rod for the point of the poker, and' 

 a ratchet catch to support the piston when the lever is withdrawn. The 

 coal-box of an ordinary fire may have a depth of seven or eight inches, which 

 will receive from twenty to thirty pounds of coal, according to the area. In 

 winter an inch or two more depth of coal may be placed over the mouth of 

 the box before the fire is lighted, and in warmer weather the box will not 

 require to be quite filled, that is to say, the piston, at the time of charging, 

 needs not to be lowered quite to the bottom. 



If it become desirable to replenish the coal-box it may be easily done, as 

 follows : when the piston has been fully raised so as to have its flat surface 

 flush with the bottom bar of the grate, a broad flat shovel is pushed in upon 

 the piston, and it becomes at once a temporary floor to the grate and a lid to 

 the coal-box. The piston being then allowed to sink, the lid is raised and the 

 box filled with a new charge of coal, when combustion goes on as in the 

 morning. This fire is lighted with great ease. The wood is laid on the upper 

 surface of the fresh coal filling the coal-box, and a thickness of three or four 

 niches of cinders or coked coal left from the fire of the preceding day is placed 

 over it. The wood being then lighted, instantly ignites the cinder above, and 

 at the same time the pitchy vapor from the fresh coal below rises through the 

 wood-flame and cinders, and becomes sufficiently heated to inflame itself, and 

 so to augment the blaze. When the cinder is once fairly ignited, all the bitu- 

 men rising through it afterward, becomes gas, and the fire remains quite 

 smokeless ever afterward. 



In the new grate, because no air is allowed to enter at the bottom of the 

 coal-box for the piston-rod fits ita opening pretty accurately there is no 



