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 comparing cooling matrix performance with varying heights and depths at a road speed of 30 mph.
| Identifier | ExFiles\Box 24\4\ Scan304 | |
| Date | 25th November 1924 guessed | |
| SHEET 1. VALUE OF INCREASING MATRIX HEIGHT ALSO REDUCING DEPTH. No ventilation. Matrix details. | Sθ | % difference from 'A'. | Critical atmospheric temperature. STANDARD. Matrix height 20¾" Depth 4.8". | 77°C | 'A' | 18°C LARGE STANDARD. Matrix height 21¾" Depth 4.8". | 74.5°C | 3.3% Improvement. | 20.5°C EAC. TUBES. Matrix height 21¾" Depth 4.4". | 77.5°C | .65% Improvement. | 17.5°C Matrix height 22¾". Depth 4.8". | 70°C | 9% Improvement. | 25°C Matrix height 23¾" Depth 4.8". | 68.5°C | 11% Improvement, | 26.5°C Figures for road speed of 30 m.p.h. | ||