This section is from the book "The National Capitol. Its Architecture Art And History", by George C. Hazelton, Jr. Also available from Amazon: The National Capitol Its Architecture Art and History.
The Hall of Representatives is one hundred and ten feet long from east to west, and fifty-five feet high ; therefore, before the echo of a sound, issueing from the center of the floor, can return to its place, it must travel one hundred and ten feet, a distance very perceptible to the ear in the return of echo. The distance will be still greater if the speaker be placed at a distance from the hearer. And as the walls, in their various breaks, return each a separate echo, their confusion must necessarily render it almost impossible to understand what is spoken.
From these plain facts it is evident that the walls of every large hall of debate should be covered with tapestry, or other material which does not reverberate sound. On reference to the original drawing it will be seen that this was intended, but neither the time nor the extent of the appropriation for furniture, which proved sufficient for the indispensible articles of carpeting, tables, chairs, desks, and curtains, would admit.
. . . it was proposed to suspend curtains between the columns round the whole internal area of the House, and others behind the seats of the galleries, and to paint the ceiling in flock. The proposal was approved, and has been executed, as far as it could be done, by hanging all the curtains; the painting of the ceiling must be postponed until the House rises. The fullest success attended this measure ; and, although the echoes of the ceiling produce in the center of the House some confusion of sound, it is a small inconvenience, which will be removed. When the size of this room is considered, it may be safely asserted that it is now as little liable to objection as any other hall of debate in the United States ; that it is in all respects superior to most others, and that, when the proposed improvements, which are of comparatively small import, are made, it will be second to none in every legislative convenience.
On this occasion a plan was submitted to and approved by the President by which the inconveniences experienced in the former House were endeavored to be obviated, and the areas both of the House and gallery considerably enlarged.
Referred to the Committee on the Public Buildings, January 25, 1830.
Upon Congress being reinstated at the Capitol, in 1820, it was found that a difficulty existed both in speaking and hearing, in the Representatives' Hall ; this was at first imputed to the resonannces and echoes occasioned by the unfurnished state of the Hall, and to the freshness and dampness of the new work. To remedy this defect, draperies were ordered to be suspended in front of the galleries, and between the columns of the Prostyle of the Logia : and carpets were spread in the galleries. These measures produced some effect in lessening the reverberations, but did not entirely remedy the inconveniencies complained of. In the Session of 1821, a large Committee, of 24 Members, was raised, to " inquire into the practicability of making such alterations in the present structure of the Hall of the House of Representatives as shall better adapt it to the purposes of a deliberative assembly." This Committee attended to the subject fully, and consulted the Architect (and such scientific persons whose opinions could be readily obtained) when several very contradictory theories and projects were suggested. The Architect had the honor of presenting the following Report:
The plan of the Hall under consideration was chosen by the distinguished Artist who commenced the restoration of the Capitol, from the most approved remains of Antiquity ; it was taken, apparently, from the designs of the Grecian and Roman Theatres, traces of which are still extant; and no form could be devised better adapted to such buildings ; the whole audience being arranged in concentric semi-circular rows, and facing the Proscenium or place of exhibition, where ail that was spoken was delivered from the stage or space in front of the semi-circle. This form has also been adopted of late in the legislative halls at Paris ; but it is not found altogether convenient for a deliberative assembly, where the speakers are seated indiscriminately, and frequently with a large portion of the members in their rear ; in consequence of which, it has become necessary there, to select particular spots for desks or tribunes, as stations for those who wish to address the assembly. If such a measure could be adopted here, it would in a great degree remove the present complaint; as it is found, when religious services are performed, that the voice of the preacher is well heard in every part of the hall, assisted as he is by the silence which the solemnity of worship enjoins, but which is too much interrupted on other occasions.
Several suggestions have been made for the improvement of the Hall : 1st, To raise the floor. 2d, To contract the space by a partition of glass, in place of the present bar. 3d, To form a level ceiling at the foot of the dome, resting on the stone entablatures, over the columns.
I cannot think that any great advantage could be derived from raising the floor, because it could not be done, more than three feet, without disfiguring the columns and destroying all the beauty of their proportions ; and the chief difficulty of hearing is occasioned by the reverberation and confusion of sounds, from the lofty and smooth ceiling, which would not be affected by this mode of alteration.
The second proposal, to reduce the space by a glass partition, is also objectionable, as, in my opinion, it would produce no effect, unless carried very high to shut out the galleries ; which the habits of our country have made indispensable ; and this mode would not remove the difficulty of the dome.
The third proposal, of a flat ceiling, affords a prospect of greater advantage than any other. It would reduce the absolute height of the room in the centre, upwards of twenty feet, in which space much of the voice is lost ; and would check, in a great measure, and perhaps wholly, the reverberation and echo complained of. Although it would be a subject of much regret, that the beauty of the form and decoration of the dome should be obscured, yet these considerations must yield to the convenience of the Legislative body. To impair the appearance of the room as little as possible, I propose that this ceiling be made of glass, and present a drawing, in which its form and construction are shown ; the panes to be made as large as convenient, and the principal ribs to be gilded. This ceiling would be preferable to one of wood or plaster, because, in that case, it would hide entirely the present dome, excepting the opening of the sky-light, which must be retained, but which would lose much of its usefulness from the angle in which the light would be received, and which would hardly reach the outer rows of the circle.
 
Continue to: