Notes
1. High Bridge Level Co. Aluminum Line Level.
2. Millers Falls No.629 Line Level.
3. Frank B. Hall Geneva, OH., Octagon Line and Surface Level, Pat. Feb. 22, 1921, (1926)
4. Hall Level and Mfg. Works, Geneva, OH., Line & Surface Level
5. Empire Level Mfg. Co., Milwaukee, Wis. Empire Aluminum Line Leve No. 25E (1927)