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| All Patents in class 148/640 | |||||
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| Picture | Number | Date | Patentee | Title | |
| 125,650 | Apr. 09, 1872 | J.A. Woodbury | Improvement in Tempering Steel Railrod Rails | ||
 | 157,566 | Dec. 08, 1874 | L. Bailey | Improvement in Hardening the Blades of Squares | |
 | 1,265,944 | May 14, 1918 | C. Napier | Process of and Apparatus for Heat Treatment of Metal Objects | |
| 2,312,839 | Mar. 02, 1943 | T.A. Waltz, A. Kullman | Flame Hardening Of Rack Bars | ||