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).
Comparison table of transformer quotations from various suppliers.
| Identifier | ExFiles\Box 32\4\ Scan031 | |
| Date | 26th November 1920 | |
| X.1581 - TRANSFORMER QUOTATIONS. 26.11.20. Firm. | Price. | Capacity. | Delivery. | Remarks. --- Met.Vickers Co.Ltd. | - | - | - | Cannot supply. B.T.H. Co. Ltd. | - | - | - | Cannot supply. Brit.Elec.Trans.Co. | £84.ea | 3 K.V.A. | 6 - 8 months. | Oil cooled. Quot. open 30 days (Oil included). Foster Eng. Co.Ltd. | £32.ea | 1 K.V.A. | 12- 14 weeks. | Oil extra £3. each. W. Mackie & Co. | -- | -- | -- | Cannot supply. Mitchells Elec. & Wlss. Ltd. | £35.ea | 1 K.V.A. | 12 - 14 weeks. | Oil extra £5-12-6. { Tappings at 5800-10000-15000 volts. Handwritten: +2.5% for delivery (oil) = £5.15.3 3/4. Tappings included. " " " | (£45 &) (£80) | 3 K.V.A. | 4 - 6 weeks. | Air-cooled. Auto & main Bowday & Co. | £40.ea | 1 K.V.A. | 8 -10 weeks. | Oil extra £5.5.0 { Handwritten: Tappings at 5000-10000-15000 volts at 15/- ea. H.W. Sullivan. | £48.ea | 1 K.V.A. | 8 - 9 weeks. | Oil included. Watson & Sons. | £45.ea | 1 K.V.A. | 3 weeks. | Oil cooled. RJA. Handwritten on right margin: X 1581 Faint text on right margin: R.R. 25M. 100/T 'C8. H.S. 11-8-20/1980 | ||