| Number | Name | Date | Kind |
|---|---|---|---|
| 958578 | Ballard | May 1910 | |
| 1684253 | Whitaker | Sep 1928 | |
| 2695374 | Jeppson | Nov 1954 | |
| 3052783 | Buron | Sep 1962 |
| Entry |
|---|
| "Direct Current Transmission," vol. 1, by Edward Wilson Kimbark, published by Wiley-Interscience 1971 (pertinent pp. 3, 4, regarding the Thury System). |