Mr. P. Carr informed me two days ago that you wished for the dimensions of the Rumford fireplaces. I therefore avail myself of the first post to send them. I state them as I have used them myself, with great satisfaction, the back one half of the opening. Count Rumford makes the back but one third of the opening. this was to accomodate them to coal; but it renders them impracticable for wood. my larger fireplaces I make 2. f. in the back & 4. f. in front; those for bed-rooms 19½ I. in back & 3 f. 3. I. in front. the opening of the former 3. f 3. I. or 3. f. 6. I. high the latter 3. f. high. the figures below will shew every thing necessary. affectionate salutations.

		suppose an old fire place, to be newly arranged, that it’s depth is from a. to b. it’s breast c. d only 4 I. then the new back must be made of such thickness as to bring the depth to 13. I. from a. to g. it must run up perpendicular to about .e. the height of the old iron back, then gather forward to f. within 4. I. of the breast, then parallel to the inside of the breast 6. I. higher to h. and then go square off to the back of the old flue .i. as the plans & dimensions of old fireplaces vary, the new work must vary also to be adapted to them observing always, as fixed principles, that the fireplace must be 13. I. deep, the back worked up perpendicular some height (say ⅔) & then brought to within 4. I. of the breast, then to rise parallel with that 6. I. more, then to go off square to the back of the old flue.
this is the form where one has a new chimney to make and can arrange every thing to their will.