THATCHEE HEAT'"G CO. 17. SPEAR, 413 �encloses the ash pit b. * * ^ The fire-pot is placed at Bufficient distance from the furnace front e to allow the hot- air chamber enclosed in the inner surrounding walls to extend around the fire-pot, between it and the furnace front. * * • At the bottom of the fire-pot, in the front part thereof, is a clinker cleaning aperture i, which extends forward to and through the furnace front, the passage way being enclosed by the plate i, so that it shall not have any communication with the surrounding hot-air chamber e'. A stopper may be used to close this clinker cleaning passage, or that part of it which leads into the fire-pot, if desired, or it may be left open to supply air to the fuel in the fire-pot. The aperture should be of sufficient width and height to permit the introduction and use of a slicer, or a po.ker, or other suitable instrument, for the purpose of slicing the fire, cleaning the grate-bars from clinker. and removing the clinker, which may be drawn out through this passage into the room in front of the furnace front, if desired, when the downward passage j is not used, in which case there should be a plate across the space between the fire-pot and furnace front, on a levai with the top surface of the grate-bars, The downward passage j, between the furnace front and grate, is an opening leading from the clinker cleaning passage down to the ash pit, for the purpose of allowing the clinker and ashes to fall from the clinker cleaning opening into the ash pit." �The second and third claims are in these words: "2. The clinker cleaning passage from and through the furnace front to and into the fire-pot, enclosed by the plate connected with the fire-pot, furnace front and ash pit, so as to prevent com- munication with the hot-air chamber surrounding the fire-pot, Bubstantially so described. 3. In combination with the clinker cleaning passage, the downward passage leading therefiom to the ash pit, substantially as described." �Varions prier structures and patents are set up as antici- pating the second and third claims on the question of novelty. One is the furnace represented by the defendants' exhibit — "0 d Philadelphia Heater." It is adduced to defeat the sec- ond claim. On the whole evidence it d'.d not contain a prao- ��� �
