The Detective’s DeskGara Moss
Proposed deduction
“Use drawer 13.”
MEDIUM · CASE FILE
The switchboard number
Medium · NORTH SIGNAL MUSEUM
Four guides translated a three-switch display into a catalogue drawer. The switches encode a number before a separate offset is applied. Also reconstruct the review register: it records who examined which source, independently of whether their later proposed answer is correct. Review slots describe order, not travel or clock times.
Read the case file below, or open the interactive desk to examine records, keep notes and submit your reasoning. These are the case materials, without the solution.
Your assignment
Who names the correct drawer?
- The analytical records answer the analytical question; worksheet records establish the review reconstruction. Candidate proposals and supplementary recollections are claims to test.
- There are 3 ordered events. Use each listed person and item once in its column. “A immediately before B” means A is in the row directly above B, with no row between them.
- 4 verified records support the complete submission. Keep the separate context note out of the proof.
- No outside facts or unstated exceptions are required. The complete board and report are assessed together.
People and accounts
Davi Lane
Proposed deduction
“Use drawer 17.”
Elin Grove
Proposed deduction
“Use drawer 5.”
Fenn West
Proposed deduction
“Use drawer 19.”
Case records
Read each record on its own terms. A claim made by a person is different from a fact established by an independent record.
LINKED RECORD
Drawer convention
The catalogue drawer number is the encoded number plus 12. No other conversion is applied.
This supplies the final offset.
CONTEXT NOTE
Display history
The switchboard came from a closed railway office.
Its origin does not change the encoding rule.
PRIMARY RECORD
Switch photograph
From left to right, the switches show ON, OFF, ON. The left, middle and right positions have values 4, 2 and 1 respectively. Add values only for ON switches.
This supplies the encoded number and place values.
RECONSTRUCTION RECORD
Review register
This is the same investigation’s document review record. There are 3 ordered events, labelled Review 1, Review 2, Review 3. Each listed person and item occurs exactly once. These slots describe record order, not times from the analytical problem.
- The event reviewed by Fenn West occupies slot 1 (Review 1).
- The event reviewed by Fenn West occurs earlier than the event involving “Drawer convention”, without claiming they are consecutive.
Use each column’s choices exactly once. Verified relationships govern the board; proposed answers and later recollections do not override them.
RECONSTRUCTION RECORD
Review cross-check
The relationships below were verified independently. “A immediately before B” means A is in the row directly above B, with no row between them. Keep relationships from all worksheet sources together.
- The event involving “Display history” occupies slot 3 (Review 3).
- The event reviewed by Gara Moss occurs earlier than the event reviewed by Davi Lane, without claiming they are consecutive.
Use each column’s choices exactly once. Verified relationships govern the board; proposed answers and later recollections do not override them.
Questions to resolve
Reconstruct the file or item order through the verified register.
When was the primary analytical record reviewed?
Use the interactive case desk to select your finding and cite the records that support it. The answer is checked there, and your progress stays in your browser.
Build your finding
Compare the records with each account. Work out what the evidence establishes, then separate that finding from anything it does not prove.