Water Temperature Gauge Not Working

We finally got my car running and driveable but we have some kinks to work out. The water temperature gauge in the dash does not seem to be working. The car is not having any overheating problems but I don't want to drive it too much without that gauge working. Any ideas what might cause the gauge to not work? Is there a fuse in the fuse block that makes the gauge work or something at the thermostat? Any thoughts would be greatly appreciated.

I hope to get some video of the car running posted in the next few days. Boy does it sound and run good. And that is without the carb totally tuned in right.