I slightly soldered one of my fingers tonight in the pursuit of history, but the gyro flux gate compass is going to work. More accurately, it still works, it's just in pieces on the work bench of my father's laboratory and the amplifier will need substituting since even if we trusted its vacuum tubes not to blow out and fry everything else, it doesn't come from quite the same system as the other parts and we're not actually sure if it would work with them. The compass itself is composed of a gyro-stabilized transmitter which is placed out in the wing or the tail of the plane so as to receive as little magnetic interference as possible from the contents of the interior while it interacts with the magnetic meridian, an amplifier which band-pass filters the 400 Hz of alternating current it gets from the plane into the excitation voltages necessary to drive the other two parts of the compass as well as efficiently circulating the unequally induced voltages which serve as the transmitter's direction signals onward, and a master indicator which the navigator reads like a regular compass dial once it has translated the amplified direction signals through its cam mechanism into the placement of its pointer, with the auxiliary option of repeat indicators to be distributed throughout the rest of the plane as needed. We have two transmitters of slightly different vintages, so we checked both of them with an ohmmeter and then with an LCR meter in order to make sure that all the contacts and coils and wires were still resisting and reacting as intended after eight decades and then we hooked each in turn up to a signal generator since we don't have a B-17 and plugged it into an oscilloscope and beheld the asymmetrically green sine wave of the three coils of the flux gate mistaking my rotating a strong magnet near them for cardinal movement through the magnetic field of the earth; it also responded to spatial manipulation, i.e. me turning it back and forth in my hands in a room full of computer equipment. We may have overdriven the transmitters slightly since we were supplying their voltage peak-to-peak rather than root-mean-square. We did have to resort to the manual from 1945 in order to be sure of the survival of the master indicator since the wiring diagram was unexpectedly unhelpful as we tried to check out the magnesyn or the motor, but mostly what it turned out to need was some contact cleaner from my father. We have no repeat indicators to worry about and as mentioned previously the amplifier is attractive but irrelevant. The connectors and cables may or may not be a pain. The point is that I am delighted that this piece of one hundred percent analog instrumentation almost certainly older than my mother works. We could tell the gyro was still functional because it rolls like a magic eight-ball under the transmitter's round plate of a window, but it was much less clear until tonight if the ghost was still in the machine and there it was like some kind of slewing heartbeat on the screen. My soldering skills remain rudimentary, but three of the four wires employed in testing the transmitters were my handiwork and demonstrably did their job and I am taking even small achievements right now. Should we succeed in reconstructing the compass completely, I will be pretty thrilled.

