Tony,

 How about building a wheatstone bridge with two of the legs being
 thermistors.   One of the thermistors will be exposed to the open air.
 The other one will be exposed to ambient temperature, but would be
 shielded from the ambient air movements.   This way, the room temperature
 will not affect the measurement.  The way this would work is that at any
 given temperature the thermistors are exposed to the same temperature, so
 the bridge is balanced, and the wind velocity will be zero.  However,
 since one of the thermistors is exposed to air movements, it will be
 cooled by air moving across it, but the shielded one won't.   Therefore a
 difference will ensue and unbalance the bridge.  This unbalance will be
 dependent on the airflow.  ie more airflow, more cooling to the exposed
 thermistor, and a greater difference in the balance of the bridge. This
 unbalance can be calibrated to give a wind velocity proportionate to the
 unbalance.   Hope this helps you out.  Or at least gives you food for
 thought.

                                               Regards,

                                                 Jim

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