It had a reputation for unreadability. As its author walked by, a student at the University of Cambridge in England was said to have remarked: “There goes the man that writt a book that neither he nor anybody else understands.” Its hundreds of equations, diagrams and obscure references didn’t help, nor that it was written in Latin, the scholarly language of the day.

Isaac Newton’s “Philosophiae Naturalis Principia Mathematica,” or Mathematical Principles of Natural Philosophy, published in London in 1687, nonetheless went on to become a scientific colossus. It unlocked the universe with its discovery of gravity and laws of planetary motion, and laid out a method of inquiry that became the gold standard. It was known as simply the Principia, the Principles.

Now, historians have discovered that the first, limited edition of the seemingly incomprehensible book in fact achieved a surprisingly wide distribution throughout the educated world.

An earlier census of the book, published in 1953, identified 189 copies worldwide. But a new survey by two scholars has found nearly 200 more — 386 copies in all, including ones far beyond England in Budapest; Oslo; Prague; Zagreb, Croatia; the Vatican; and Gdansk, Poland.

Mordechai Feingold and Andrej Svorencík, writing in the current issue of Annals of Science, a quarterly journal, said the unexpected total suggests the book had “a much larger print run than commonly assumed” as well as “a wider, and competent, readership.”

Dr. Feingold is a professor of the history of science and the humanities at the California Institute of Technology in Pasadena and Dr. Svorencík, his former student, is now a postdoctoral researcher at the University of Mannheim in Germany.

The two scholars, by analyzing ownership marks and notes scribbled in some of the books, as well as related letters and documents, found evidence contradicting the common idea that the first edition interested only a select group of expert mathematicians.

They said the finding also implies that current historians have underplayed the early impact of Newton’s ideas. It necessitates, they write, “a major refinement of our understanding of the contribution of Newtonianism to Enlightenment science.