Washington Septr. 14th. 1807
I much fear that in performing my duty, and endeavoring to give you all the information possible on the State of the public buildings, I claim an unreasonable portion of your time & attention.—My present letter is on a subject on which I see only one mode of proceeding, and that one, involves a mode of finishing the roof of the North wing on which I solicit your opinion and direction: especially as the present method of covering the South wing will not correspond with it, and I might appear to have chosen a termination for the North, which, is consonant to my ideas for the South roof, from predeliction rather than necessity.
Fig. 1. This fig. exhibits a plan of the central lobby at the level of the roof, with all the Chimnies in the proper places as they have been formerly carried up, and stand at present. They have been a good deal twisted about in order to get them to stand in the situations in which they are seen; situations which were judged the most convenient for the purpose of carrying all the water of the roof to one point, at which there is a Cistern of very Small dimensions, too small to be useful either for a Water–closet or in case of fire. From the position of the chimnies & their interference with the Gutters, the principal leaks arise, & if this were the only cause of changing their position it would be a sufficient one. The Walls have been so long & thoroughly soaked, that the bricks have lost all adhesion by the mortar, & may be taken up singly by the hand.
Besides their inconvenient situation relatively to the drainage of the roof,—they would, on covering the Wing with a roof similar to that of the South Wing, protrude themselves through the roof in the most irregular manner, as they differ materially in the size & position of the stacks: and as none of them are nearer than 13 feet to the Center of the dome, it would be requisite to carry them to some higth to prevent their being overblown.
Under these circumstances there appears to me to be no choice but between, the carrying them up thus irregularly,—and collecting them into some regular & if possible ornamental form, & conveying therein this manner above the center of the roof at least 10 feet above the highest bend,—otherwise they will inevitably smoke when the wind is in a direction opposite to that of the Slope of the Chimney, as experience daily proves.
Fig. 4. & 5. exhibit the manner in which I propose to accomplish this object. The roof itself assumes the exact form of that of the Southwing, with this only different that it is crowned with a cupola: The diameter of this cupola cannot, to admit the 16 Chimnies, and also eight windows for the purpose of lighting the Vestibule of the Senate Chamber be less than 20 feet in external diameter. It must be built of Freestone in order that it may bear this & Light in its parts as possible. Nothing will be more easy than its construction. The dome rises necessarily so high that the chimnies will every where have a very good ascent previously to their entering the perpendicular sides of the cupola as shown in Fig. 4.
I have in fig. 4 continued the section to the external Wall in order to give an idea of the elevation of the dome above the Ballustrade. This section also shows the roof now standing & which must remain for the present. It will not be seen from below.
The workmen are now engaged in turning the Dome of the Vestibule, being on the level of the frieze ornamented by a range of wreaths.
I have no doubt whatever of the house of Rep. in Congress being very satisfactorily accomodated this Session, in the Southwing. Tomorrow we strike the Scaffolding in the great room.
I am with the highest respect Yours faithfully
B Henry Latrobe
DLC: Papers of Thomas Jefferson.