Jupiter Jones’s Method
The Mystery of The Invisible DogJupiter Jones turns apparently supernatural events into testable questions, then uses physical clues and human routines to solve the case.
increasing
Bearing strength in each event
decreasing
The Formal Interview

The Formal Interview
Establishing the facts
Jupiter Jones asks Fenton Prentice what is happening before accepting the case. He also has Bob Andrews summarize what research has already uncovered about the client.
Confidence with limits
Jupiter is methodical rather than credulous, but he does not dismiss Prentice’s fear. His willingness to investigate makes room for evidence that may initially seem impossible.
The Ointment Experiment

The Ointment Experiment
A practical device
Jupiter Jones prepares Investigative ointment that leaves dark marks on anyone who touches treated surfaces. It gives the boys a way to test the apartment’s supposed invisible visitor.
A useful distinction
The experiment proves that someone has handled the desk, but it cannot identify every presence. Jupiter treats the result as progress, not a complete solution.
The Open Questions

The Open Questions
Sorting the strands
Jupiter Jones separates the apartment shadow, the burglary, and the phantom priest into three puzzles. He resists collapsing every strange event into one explanation.
Evidence and uncertainty
He recognizes that Sonny Elmquist may be a wanderer but cannot yet connect that ability to the theft. His disciplined doubt keeps the investigation from settling too soon.
The Water Insight

The Water Insight
A remembered story
Jupiter Jones recalls an invisible glass weapon hidden in water and applies the same principle to a transparent sculpture. The pool’s tile colors provide the missing camouflage.
From theory to test
Rather than merely announce a solution, he enters the pool and searches. The discovery confirms the idea and converts a clever inference into physical proof.
The Hospital Deduction

The Hospital Deduction
Following the alibi
When the apparent thief escapes with the bogus package, Jupiter Jones does not chase blindly. He reasons that the culprit has a reason to remain in the clinic.
The accusation tested
Jupiter finds John Murphy in his room with the ransom parcel. His confidence is supported by a coherent chain of clues, not by intuition alone.
Late afternoon during Christmas week
Early morning after the first interview
The morning after Jupiter is locked in the church
The afternoon before the ransom appointment
Late afternoon on the ransom day