and the face oi the stone masonry is provided. 

 This method of construction is open to some 

 question. Sometimes this air space is filled with 

 powdered asbestos in order to further protect 

 the stone masonry against intense heat. 



It is also advisable to construct the hearth, 

 or floor of the firebox, with fire-clay brick 

 unless, as in the fireplace shown on plate VII, 

 figure 6, the surface of the hearth is level with 

 the surrounding ground, in which case it may 

 be equally as well constructed of mineral earth 

 or natural porous soil. 



In the fireplace with closed back (pis. Ill, IV, 

 V, etc.), the only real draft control is in the 

 orientation with respect to the direction of the 

 prevaihng wind. A raised back somewhat im- 

 proves the draft, and a movable solid plate 

 may sometimes be used in connection with the 

 raised back to further control the draft. 



The chimney notch shown in plate VIII in- 

 creases the draft by restricting the gases to a 

 definite limited passage. The maximum con- 

 trol of draft is obtained where a chimney is 

 used. The draft is further controlled by damp- 

 ers in the doors at the front of the firebox and 

 also by dampers in the chimney. The chimney 

 may vary in height, as shown in plates X and 

 XII. 



The door on the front of the firebox may be 

 of cast iron or sheet iron, in conformity with 

 the materials used for the cooking top. Besides 

 being hinged so that it can be fully opened 

 there may be, as shown in plate XXII- A, figs. 3, 

 4, and 5, a small opening in the door to provide 

 draft. 



A draft control necessary to maintain the 

 desired fire may be provided in one of three 

 ways as foUows: 



A. By an ashpit under the firebox, on the front of which 

 is a door which may be opened or closed to produce 

 greater or less draft. 



B. By an opening in the door as shown in plate XXII A, 

 hgures 3, 4, and 5. 



C. By a damper constructed m the chimney (pi. XXII, 

 fig. 3), or by a damper constructed in the rear of the 

 firebox at the point where the flue enters the chimney. 



It is apparently necessary in some localities 

 of extreme moisture conditions, and especially 

 in high altitudes where much fog is prevalent, 

 to procure a maximum draft by providing an 

 ashpit under the firebox. The ashpit is not 

 generally recommended nor usually essential 



in the average camp stove. It ought not to be 

 constructed unless the requirements for max- 

 imum draft, to burn wood not thoroughly dry, 

 make such an ashpit indispensable. 



Under normal conditions, sufficient draft 

 control may be had through the adjustment of 

 the doors in the ftrebox. Sometimes the draft in 

 the chimney is controlled by a pivoted iron plate 

 on the top of the chimney. The value of this de- 

 vice is open to question. The built-in type of 

 damper with the revolving metal shield (pi. 

 XXII, fig. 3) is the most effective; but its opera- 

 tion is not fool-proof. No damper should be in- 

 stalled which does not leave a limited portion of 

 the flue (approximately 35 percent of its area) 

 free when the damper is practically closed. 



TOP GRATE OR TOP PLATE 



The top of the stove or fireplace may consist of 

 a grate (simple bars or a fabricated grate) or 

 a solid plate. In some instances, in place of a 

 definite grate a heavy electric welded wire 

 mesh is being used. This type of grate is less 

 expensive than the iron plate. The sohd plate 

 provides better draft and a better control over 

 the draft. Its use reduces the fire hazard and is 

 sometimes necessary in certain locations where 

 the fire hazard is great. In some States laws 

 have been enacted making it compulsory to use 

 on camp stoves a solid plate for the top of the 

 stove and a door on the front of the firebox 

 which at all times prevents any possibility for 

 sparks to escape and cause a forest fire. In 

 picnic fireplaces, except those used for warm- 

 ing purposes, the grate is generally adopted 

 but in a few instances a solid plate is used. 

 On camp stoves, where the camper desires to 

 keep the pots and pans from smudging, a solid 

 plate is generally used. In many instances, and 

 where the use justifies the expense, a combina- 

 tion grate and plate top is used (pis. X and 

 III A). 



In some fireplaces, a successful method of 

 cooking is that of using a reflector plate of 

 sheet iron or other metal, which can be stood 

 at an angle of approximately 60° immediately 

 in front of the opening of the fireplace, and sup- 

 ported by an arm which keeps the plate at the 

 proper position in relation to the fire. This 

 contrivance is often used in place of a grate or 

 plate over the top of the fire, and it may be 

 home-made or purchased from some supply 



15 



