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We want no more than 1V across two-thermistor voltage divider. Mouser sells good part from Analog Devices: 
Instrumentation amplifier, AMP-04: Run at +-12V to get good SNR at other end. 
For thermistors that are 150K at room temp, expect about 10 mV of delta-V for 1 degree temp change. So we could run at a gain of around 1000, get 1V of signal per deg C and dynamic range of 10 C/m gradient.
Pins needed:
V+=+15V
V-=-15V
Power ground
dT signal +
signal -
T signal from TMP36
So we need 6 conductor shielded cable.
Can use same DB9 setup as wind sensor scheme.