Classic arrangement for two pickups, with the pickup hot wire connected to the middle of the vol pot, for independent volume control. Vol pot is 1 Meg and tone pot 250 K.
Below a 1966 H17 "by Heath" pickguard wiring (Pickups are the "mustache" Golden tones). Note these are the small pots, scroll down to see the S1478 pickguard with standard sized pots. They all have same value and codes : R-15 / 1Mo for volume, R-20 / 250ko for tone.
You can see a ground wire going from the jack to the tailpiece, it looks original (the hole is painted..) but I'm not sure all models had this ground wire from origin.
The "big black box" switch is marked "CARLING made in usa / 25A-250VAC - 10A-125VAC". I guess earlier models used the usual Switchcraft model working with blades (see below the S1478 photos).
More Pictures : below are photos from a 1965 Silvertone 1478 "Silhouette", same as a Harmony H19 (but Pickups are the "Silver Diamonds"). These are the larger "standard sized" potentiometers. They all have same value and codes : R-15 / 1Mo for volume, R-20 / 250ko for tone.
