from The Century Dictionary.
- noun In telegraphy, a box containing terminals to which telegraph-wires are connected for convenience of testing.
Sorry, no etymologies found.
Earlier on I had noted marked on a Corps signalling-map a test-box between the quarry and the canal and another one along the railway embankment, not far from the retiring positions assigned to the batteries.
I stood outside the test-box that had become a sort of Brigade H.Q. and listened to the waspish crack of our 18-pdrs. sending defiance to the enemy.
The six signallers -- plus a terrier -- had crowded into the tiny sandbag shelter that protected the test-box.
For my second test-box, I used a late beta of the outstanding Debian-based
10.30 P.M.: I had reeled out my lines alongside the railway from the test-box to D Battery and to C and A, who, because of the nine guns the brigade had lost in the morning, had become a composite battery.