Jim, Dr. Breckenridge's assistant and a watchmaker's apprentice, rents a room above Miss China's Tenkai restaurant and boarding house. He and Breckenridge constantly struggle financially, often delaying rent to fund their inventions. An unspoken romantic tension simmers between Jim and Miss China. While her infatuation is clear, his feelings remain less obvious. Misunderstandings arise, like his visits to florist Lily sparking Miss China's jealousy. His grandest gesture employs Breckenridge's Space Reflex Telescope to etch "Happy Birthday Miss China" onto the moon's surface, culminating in them sitting together on the projected miniature moon.

Jim collaborates with Breckenridge on other projects, including a functional matter teleporter. He pragmatically leverages Miss China's superhuman strength, provoking her to bend steel bars needed for their machines. As part of the Scientific Boys Club – Breckenridge, Cooper, Gordon, Shepard, and Jim – dedicated to space exploration, he participates in unconventional inventions. These often cause unpredictable problems for their landlady and lead to later adventures, like etheric current travel to Mars. Jim shares Breckenridge's frustration over their inventions' lack of recognition or financial reward despite achieving seemingly impossible technological feats.