Given the city’s myriad public institutions, it is surprising that New York lacks a museum devoted to the history and practice of watchmaking.

As of October, however, research lovers probably think that the city has something even better: the Jost Bürgi Research Library, housed at the Horological Society of New York’s headquarters on West 44th Street.

Comprising more than 25,000 items, including books, magazines, periodicals, pamphlets, postcards, advertisements and all manner of watchmaking ephemera, from horological-themed postage stamps to syllabuses for watchmaking courses, the collection fills nearly 800 linear feet of shelf space (which is longer than eight basketball courts laid end to end).

It was made possible thanks to a single donation by Fortunat Mueller-Maerki, a Swiss-born former recruiting executive who, over the course of 30 years, amassed at his home in Vernon Township, N.J., what the society has described as one of the largest horological libraries in private hands.

“It’s every collector’s dream that he finds an institution that is custom tailored to that subject and has nothing, basically, as far as a library,” Mr. Mueller-Maerki, 76, said in a recent phone interview.

Founded in 1866, the society had a small library of about 200 books before Mr. Mueller-Maerki donated his collection in 2019. The highlights of his collection include rare books from the 17th, 18th and 19th centuries (the oldest is a 1652 book in Latin that chronicles historical events), as well as an entire section dedicated to children’s books about timekeeping, some marked and doodled in by their previous owners.

Miranda Marraccini, the society’s librarian, said she was impressed by the variety of Mr. Mueller-Maerki’s holdings. “There are not that many libraries that have that kind of depth and breadth,” she said.

Mr. Mueller-Maerki came by his love of horological books serendipitously. When he was attending the University of Bern in Switzerland in the 1960s, he spent a semester living with his grandfather in Zurich.

“One day, he came home and told me that he was the legal heir to a tiny estate,” Mr. Mueller-Maerki recalled.

The estate’s furnishings included an Austrian table clock that was some 250 years old, and Mr. Mueller-Maerki ended up placing it on his night stand. “That was my introduction to the world of horology,” he said.

Instead of devoting his time and energy to collecting timekeeping objects, however, he turned to books about horology. “I am more an ideas person than a crafts person, so I started buying books on clocks and watches, and that’s how I got sucked in,” Mr. Mueller-Maerki said.

He moved to the United States in 1973 to attend Harvard Business School, and eventually settled in New York City as a representative of the Swiss executive search firm Egon Zehnder. In 1982, he joined the National Association of Watch and Clock Collectors, a nonprofit membership organization based in Pennsylvania, “and that became my horological anchor in the United States,” he said.

As chairman of the association’s library committee, Mr. Mueller-Maerki began acquiring books for the organization, and often bought two copies so he could keep one. “I started buying books in all languages, even those I don’t speak,” he said, and over the years he became what he described as “a hoarder of information.”

“If I got a letter from somebody abroad that had a horological theme on the stamp,” Mr. Mueller-Maerki said, “I’d keep that stamp and give it a catalog number.”

The bookcases at his home were stuffed with volumes on watches and timekeeping by the time a fortuitous series of events linked him and the horological society.

In 2018, the society leased a 500-square-foot room in the General Society of Mechanics & Tradesmen building on West 44th Street, intending to use it for watchmaking classes. (Previously, a member had been allowing the society to hold classes in a space at his funeral home on the Upper West Side of Manhattan.)

Afterward, Nicholas Manousos and Carolina Navarro, who were the society’s president and director of public relations at the time, were touring the classroom, and the landlord showed them a vacant 2,000-square-foot library space across the hall; the Holland Society of New York had occupied it before moving to a larger headquarters.

“The problem was, we would need thousands of books to fill the shelves,” Mr. Manousos, now the society’s executive director, said during a recent interview at the new library.

The society declined to lease the library space. But less than a month later, Mr. Mueller-Maerki, working through a friend from the National Association of Watch and Clock Collectors, approached the society with an offer to donate his collection.

“In 2019 we signed the lease on this room and got prepared to start moving the books in early 2020, and then Covid hit,” Mr. Manousos said. “That kind of slowed everything down, but we finally had five truckloads of books delivered here over two years.”

To honor Mr. Mueller-Maerki, the society named him the librarian emeritus — although Ms. Navarro, now the society’s deputy director, said that he still comes to the library several times a month and has helped the staff with a number of tasks. “The library would not have been possible without his contribution,” she said.

Mr. Manousos said the library, which is named for the 16th-century Swiss clockmaker Jost Bürgi, furthers the society’s mission “to advance the art and science of horology.

“We want to promote horological research and provide a place for people to come if they want to read or learn,” he added.

The library is open to the public on weekdays, although the society encourages researchers to make appointments through its website, hs-ny.org.

To simplify such research, the library is being reorganized. “Right now, the books are in alphabetical order, but I’m excited to have them officially cataloged according to Library of Congress specifications,” Ms. Marraccini, the society’s librarian, said. “Instead of being alphabetical, it’ll be by subject. And books that are on similar topics, like decorative arts or engineering, will be near each other.”

“We also have a lot of periodicals in matching bound volumes,” she said. So if, for example, someone wants to see an article from 1959 in the horological publication Deutsche Uhrmacher-Zeitung, she said, “we’ll have it. There’s a lot of stuff here that probably doesn’t exist anywhere else.”