James Copcutt¹ to Faraday   19 September 1861

The Fitzmaurice Oil Gas Light & Coal Gas Light Works, | Factory, St. John’s Square, Clerkenwell. E.C. | September 19 1861

To Professor Faraday

My Dr. Sir

Having worked with Major Fitzmaurice, will you allow me kindly to inform you of the power of light which I have obtained from Gas made by the Retort (represented in the enclosed prospectus which is yet unpublished²) from Rosin-Oil, and used with a Gas burner of precisely the same diameter and with the very same chimney & Iron Condensor as used for the 4-wick Fresnel Oil-Lamp. The Consumption of the so called Rosin-Oil gas was under 40 Cubic feet per hour, and regulated by properly arranged stopcocks, the flame being as long as 5 inches in the bulk or most dense part - the maximum height being 7 inches, all perfect combustion and smokeless. - The Candle power by Bunsen’s Photometer³ was 287 sperm candles burning 120 gramms per hour, the pressure 1 inch. The 4-wick oil Lamp, which stands by its side, and which I would have pleasure to show to you hereat privately at any hour you could come, both Oil lamp and gas Light, the comparison of the lights is thus:-

Dr. Sir, as these results are facts reproducible at any hour and in any place, to obtain which we have worked incessantly, and so as to dispense with the complications, and, certainly, the expense, of Lime Lights, or Fitzmaurice’[s] first Light, - powerful as they are, and easily managed by proper persons,- may I ask you privately and confidingly for the encouragement your opinion would give to me, if this power gas-Light is fit for Lighthouses?

Dr. Sir, | Truly yours: James Copcutt.