The Old Farmer's 2012 Almanac has an article on Wilbur L. Scoville the founder of the Scoville Chile Heat Unit. He was a chemist for Parke Davis Pharmaceutical Company. He was tasked with developing a method to gauge the "heat" of variuos chile peppers. The results would aid the company in using capsaicin in salves for sore muscles. The rest of the article describes how he accomplished this.
Scoville Chile Heat Chart
TYPE OF PEPPER SCOVILLE HEAT UNITS
Pure Capsaicin 15,000,000
Pepper Spray 2,000,000-5,300,000
Naga Viper 1,359,000
Bhut Jolokia 1,000,000
Red Savina 577,000
Habanero 200,000-350,000
Chiltepin 100,000-250,000
The rest of the peppers are 50,000 or less Scoville Units.
Scoville Chile Heat Chart
TYPE OF PEPPER SCOVILLE HEAT UNITS
Pure Capsaicin 15,000,000
Pepper Spray 2,000,000-5,300,000
Naga Viper 1,359,000
Bhut Jolokia 1,000,000
Red Savina 577,000
Habanero 200,000-350,000
Chiltepin 100,000-250,000
The rest of the peppers are 50,000 or less Scoville Units.