with Reference to Sound. 349 
On re-visiting the College the present season, and repeating our — 
experiments in these rooms, we found the effect of the remedial 
measures adopted to be remarkably striking. In one room, which 
ad been treated simply by papering upon the solid walls and ex- 
tending festoons of cotton cloth from the apex of the dome to 
the corners and centre of the cornices in each side, the reverbe- 
ration was reduced to four and a half seconds; and in others, in 
Which a partition of cloth was stretched across the room horizon- 
tally, from the opposite cornices, thus completely shutting off the 
arched ceiling of stone, and substituting a level surface of yield- 
ing canvas, its duration was only half a second. By whose sug- 
gestion these simple contrivances were tried, we could not learn, 
pe retroe they originated with the skillful architect of the 
uilding. . 
Another argument that such is the nature of reverberation, is 
derived from the fact that those apartments found to possess the 
quality of a whispering gallery, (which is generally explained on 
the principle of the conduction of sound along the surface of the 
walls and ceiling,) are always domed or of ellipsoidal shape, and 
they are those in which the reverberation is also greatest. Among 
the most celebrated of these is that of St. Paul’s Cathedral, (a 
circular and domed apartment about one hundred and twenty feet 
i diameter,) in which a whisper is conveyed two or three hun- 
ted feet. The shutting of a door produces a rumbling like dis- 
fant thunder. The rotunda of the Capitol at Washington is 
hinety-six feet in diameter and ninety-six feet high, the dome of 
Which is a fine whispering gallery. The reverberation in this 
lege, Which extends upward the whole height of the building, 
“immer of 1843, are still fresh in memory. The principal 
apartment here (called Washington’s Hall) is two hundred and 
pee ny es 
mg in reference i tion of these rooms, he says: “ are, 
nated arate cotennien tinea and these results were an- 
Ucipated in the earliest stages of the work; but as Mr. Girard left no ona 
Per in’reference to this part of the design, we were compelled to take the letter 
‘the will as our guide, let the results be what they might. meen 
