Faded ink stamps of the Mechanics’ Institute Library dot the book’s pages, which are spotted with age and darkened by smoke.

The book, an 1875 first-edition collection of poetry, “Echoes of the Foot-Hills,” was thought to be lost forever but was returned in April to the private, nonprofit library at the edge of San Francisco’s Financial District.

On April 18, 1906, a catastrophic earthquake and ensuing fires destroyed nearly 500 city blocks and killed an estimated 3,000 people.

The San Francisco Public Library lost 138,000 volumes to the fires. About 15,000 books were checked out, and of those 1,500 were returned.

The original brick Mechanics’ Institute building collapsed, destroying about 200,000 volumes in its main collection.

Myles Cooper, the library’s manager and archivist, said the library had a few books that survived from 1906, some of which were most likely saved because they were checked out at the time.

Of “Echoes of the Foot-Hills,” Mr. Cooper said in an interview on Sunday: “It could have been in the rubble, and somebody took it. Or it could have been at somebody’s home that caught fire, and then was in the rubble.”

The name of a San Franciscan, Agnes Quigley, appears inside the book.

The library does not have records of the books that were checked out at the time of the earthquake and Ms. Quigley’s connection to the book is unknown, Mr. Cooper said.

The Mechanics’ Institute Library was founded in 1854 — more than two decades before the San Francisco Public Library opened — to serve a large population of out-of-work miners who needed vocational education.

Today the library has more than 110,000 volumes housed in a 1910 Beaux-Arts building, Mr. Cooper said. It has about 2,200 household memberships.

Mr. Cooper noted that “Echoes of the Foot-Hills” was certainly still part of the library’s collection because it did not have a stamp to indicate that it had been discarded or withdrawn.

“It’s obviously sustained damage from fire, but not so much that you would want to completely toss it out,” he said. “It doesn’t smell of smoke. It’s not charred in a way that is chalky and gets on your hands.”

The book is available for patrons to read only in the library.

“They don’t have to wear gloves or anything, just make sure their hands are clean,” Mr. Cooper said. “It’s really beautiful, it’s been read, it’s been loved, and there’s no indication of any repairs to the book.”

Randall Tarpey-Schwed, a book collector and library member, found the book on a website that deals in, among other things, rare books and collectibles. How it reached that previous owner is unknown.

Mr. Tarpey-Schwed said he was curious whether any books had survived the 1906 earthquake and fires, by virtue of having been checked out.

“There was no place to return the book, at least for a while, or to reapply Gertrude Stein’s famous quote, there was no ‘there there’ to return the book to,” he said.

“The book is not worth much monetarily,” Mr. Tarpey-Schwed said. “It is, after all, a soot-stained book with a lot of old library stamps. But as a survivor, it is priceless, and I knew immediately I wanted to return it to the library.”

The book’s author, Bret Harte, might have been a library member, Mr. Cooper said. Many writers and artists have been members, he said, but full membership records from before the earthquake are gone.

“He’s a well-known literary figure here in California and very celebrated,” he said.

Mr. Cooper described the book as “an actual piece of history, it’s of its time, and it’s about that sort of pioneer immigrant experience that so many people here in San Francisco still experience as newcomers” who came “for a better life, to escape something in their home country, or they come here because of the economy.”

“It’s just so much a part of San Francisco to have these economic cycles,” he added. “So it really speaks to that.”

That was true of Agnes Quigley, too.

Mr. Tarpey-Schwed found that she had posted an ad in 1898 in The San Francisco Call: “Young girl from East wishes situation as chambermaid and care of children.”