Sir Joseph Larmor

Sir Joseph Larmor was a mathematician and president of the Newtonian Mathematical Society whose role in Rong Youying’s story linked her ingenious bridge design to academic recognition in Cambridge and to the later reputation of University N. He set a formal reward for improving on the best existing design, then brought her model back to China and arranged for it to be built on the university grounds.

Mathematical Challenge and Recognition

At the time Larmor was president of the Newtonian Mathematical Society, students at Cambridge University had long tried to reproduce Newton’s Mathematical Bridge on paper. The bridge’s 7,177 timbers and 10,299 tangent planes made the problem exacting; designs requiring more than 1,000 nails had been found, but few came in below that mark. The closest prior result was an Icelander’s design using 561 nails.

Larmor promised a doctorate in mathematics from Cambridge University to anyone who could improve on that figure, even by a single nail. Rong Youying, known in the West as Rong ‘Abacus’ Lillie, surpassed the challenge decisively: her model required only 388 nails. She received a university certificate for a doctoral degree from Cambridge. After the award ceremony, she conversed in Italian with a don, a moment that also displayed her command of another language.

Bringing the Model to China

In the summer of 1913, Larmor visited China carrying a 1:250 model of Rong Youying’s bridge design. The model was constructed in the grounds of University N, which had previously been known as Lillie’s Academy of Mathematics. Its presence gave the university a visible link to a celebrated Cambridge mathematical challenge and further increased its fame.

The narrative calls Larmor the third person to bring University N to prominence. His contribution was distinct from Rong Youying’s: she had designed the low-nail model, while he carried it across continents and helped establish it at the institution where she had returned to serve as head of mathematics.

The Model’s Destruction and Larmor’s Legacy

Larmor’s gift did not survive the institution’s later destruction. In October 1943, Japanese bombing burned University N to the ground, and the 1:250 bridge model was lost in the fire. Rong Youying had died in childbirth the year after Larmor’s 1913 visit, before reaching forty; by the time of the bombing, she had been dead for twenty-nine years.

The model’s fate gives Larmor’s role a material afterlife: his gift briefly made the mathematical achievement present on the university grounds, but war destroyed the object that embodied it. What remains in the account is the chain of recognition he helped set in motion—from the Cambridge challenge and the 388-nail result to the model’s construction in China—and the contrast between that institutional fame and the loss of both its designer and her work.