From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Table of leakage measurements in micro-mhos/mils for various materials at different angles.
| Identifier | ExFiles\Box 39\3\ Scan309 | |
| Date | 1st December 1924 | |
| RR 238 (100 BKS.) IDB 461-B. 12.24) MP 306975 ROLLS-ROYCE LTD. INSTRUCTIONS. To Order No. Customer's No. 19 Signed This Sheet must be filed on completion of the work. Leakage (micro-mhos / mils) Material | 20° | 40° | 60° | 80° | 100° | 80° | 60° | 40° | 20° Cont'l boke'ce .033 | 1.24 | 3.52 | 4.87 | 6.80 | 5.60 | 4.07 | 1.82 | .75 | .077 " .065 | .41 | 8.47 | - | 13.90 | 15.50 | 12.50 | 10.40 | 4.50 | .83 " .13 | | .55 | 2.97 | 4.15 | 4.33 | 3.47 | - | .27 | .07 Embelenque cloth .032" | 2.98 | 4.00 | 4.92 | 6.40 | 5.58 | 4.10 | 2.42 | 1.23 | .068 " paper .020" | .47 | 1.21 | 2.10 | 2.76 | 1.45 | - | - | - | - | ||