The last hour of the loan

A target both instruments can follow

A tether-material bench needs extension readings that can be separated from motion elsewhere in the apparatus. The borrowed NQ-17 comparator gives Reed and Voss one more session before its January 8 return. The first paired hour showed mostly shared change; it did not establish that the local target was still.

They plan the final unloaded session on January 4 and perform it January 6. KIS-61 and NQ-17 retain their instrument mounts on the intake table. Initial displays are 4 and 130 micrometres. Neither display is tared during the session; the table below subtracts the retained starting readings. No strip, applied force or calibrated travel is introduced.

Agreement follows the target

At zero, ten, thirty and sixty minutes the displayed changes are 0/7/9/9 micrometres on KIS-61 and 0/6/8/8 on NQ-17. These are new performed observations, not revised numbers for December 30. After the stationary hour, Reed moves the common local target by hand while Voss records both readings. Each channel adds four micrometres. Attempted manual restoration leaves each two micrometres above its reading at minute sixty.

The arithmetic difference stays at one micrometre after minute ten, including while the shared target is deliberately moved. This is a concrete reason that agreement cannot establish target stationarity. The movement is uncalibrated, the absolute displacement remains unknown, and neither scale is thereby certified. The residual two micrometres is a local target offset after a hand adjustment, not a measured strip return or a passed six-micrometre return test.

The case leaves the table

On January 8 Voss and Reed return NQ-17, its stand and case to North Quay Instrument Cooperative. The handover closes the short loan on time. No renewal is sought for this session; subsequent Meridian work cannot assume the comparator remains available.

KIS-61 and KB-2 remain at Meridian. Loading and acceptance stay withheld. The 25-micrometre displacement budget, six-micrometre return allowance and 1000-micrometre bidirectional grid are unchanged. Before another loan, the team will specify which target and support motions a reference must separate, and the verified range and uncertainty it must cover. Nominal one-micrometre divisions supply none of those guarantees.

Results at a glance

Related records

• Two readings of the same stillness
• The zero after unloading