THRESHOLD LOG 05-B3

Designation: Stairwell S-17

Apparent timestamp: 09:41 / 22:08 / 00:00

Entry method: Unmarked fire door from corridor junction

Environmental Baseline

Incandescent bulbs, 2700K, output fluctuates between 40% and 90% without pattern.

Ambient temperature 16.2°C at base. Temperature rises 0.3°C per landing. Humidity 61%.

No air movement. Pressure increases with ascent.

Background sound is a soft metallic click every 4.7 seconds. Source undetermined. Volume remains constant at all heights.

Concrete stairwell, estimated 12 landings. Counted landings after full ascent: 9.

Steps: painted gray concrete, 18 cm risers, 28 cm treads. Wear marks appear only on the left side of each flight.

Handrails: painted metal, cold to the touch. Temperature of rail does not match ambient air.

Landings measure 2.1 m by 1.8 m. Wall color shifts from institutional green to beige between landings 4 and 5. No transition zone visible.

Doors present on every landing. All locked from the stair side. Labels read "FLOOR 3" on every door.

Ascent of three flights returns explorer to the entry landing.

Descent of the same number of flights places explorer on a landing with different wall color.

Footfalls produce delayed echoes. The delay increases by 0.2 seconds per flight ascended.

A single light fixture on the fifth landing emits no visible light yet registers 180 lux on meter.

Wristwatch loses 11 minutes during a 4-minute climb.

None recorded.

Exit not achieved.

Explorer remains on the circulating landings.

Recording device battery shows 47% remaining after 90 minutes of continuous operation. Expected drain is 12%.

No residual effects noted on personal equipment after temporary return to entry point.