A thermostat is NOT a thermometer. A thermostat controls the hearing pad based on a temperature sensor.
You also need better thermoneters. You need one that has a probe
This thermometer is good, costs $12 at Walmart and measures 2 temperatures (hit side and cool side) as well as humidity
Here are some good thermostats. (don't bother with the crap sold in pet stores, it isn't worth your money.
http://www.amazon.com/gp/aw/d/B000NZZG3S
You must have a thermostat to regulate a heat pad, otherwise they can and will get hot enough to kill your snake.
You should unplug the heat pad until you have a thermostat.