Today in Science History - Quickie Quiz

The Iron Dome of the Capitol

from The Science Record (1875)

[Science students usually learn that the result of thermal expansion requires architects designing long bridges to include expansion joints. A more interesting example of thermal expansion is the way the statue moves during throughout day on top of the iron dome of the Capitol building in Washington, D.C.]

U.S. Capitol Dome with Statue of Freedom

The 96-ft diameter cast iron U.S. Capitol Rotunda Dome, topped by the 19½-ft bronze Statue of Freedom (finished 1863).
Photo by Architect of the Capitol. (source)

[p.289] THE iron dome of the Capitol at Washington is 300 feet high, and is surmounted by a metallic statue. In reply to an inquiry as to whether there was a daily movement of the statue, due to the heat of the sun, the architect, Mr. Clark, gives the following particulars:

“The statue on the Capitol has a motion resulting from the unequal expansion of the opposite sides of the dome. The entire length of the line of oscillation of the plummet from the eastern limit to the western limit is only four and a half inches, which would make the inclination in the morning two and a quarter inches to the west, and in the afternoon the same distance to the east. This apportionment of the distance for morning and evening, however, is not strictly correct, and for this reason: that in the morning the east side of the dome is rapidly heated, while the west side is chilled by radiation through the night. Now, as the sun passes to the western side of the dome, this side is heated, but as the east side still retains a good portion of its heat, the expansion is more nearly [p.290] equalized on both sides, and the inclination of the statue to the earth to some extent counteracted, so that the inclination to the west is a little greater than that toward the east. The variation is probably about the same all the year round, the extra contracting by cold on one side of the dome during the winter producing the same effect as the extra degree of expansion by heat on the other side in the summer.”

From: Alfred Ely Beach (ed.), The Science Record: A Compendium of Scientific Progress and Discovery (1875), Vol. 4, 289-290. (source)

Nature bears long with those who wrong her. She is patient under abuse. But when abuse has gone too far, when the time of reckoning finally comes, she is equally slow to be appeased and to turn away her wrath. (1882) -- Nathaniel Egleston, who was writing then about deforestation, but speaks equally well about the danger of climate change today.

Carl Sagan: In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) ...(more by Sagan)

Albert Einstein: I used to wonder how it comes about that the electron is negative. Negative-positive—these are perfectly symmetric in physics. There is no reason whatever to prefer one to the other. Then why is the electron negative? I thought about this for a long time and at last all I could think was “It won the fight!” ...(more by Einstein)

Richard Feynman: It is the facts that matter, not the proofs. Physics can progress without the proofs, but we can't go on without the facts ... if the facts are right, then the proofs are a matter of playing around with the algebra correctly. ...(more by Feynman)