Note 56 — PART SECOND. NOTES ON THE ILLUMINATION OF LIGHTHOUSES, WITH SHORT NOTICES OF THEIR EARLY HISTORY. (continued 2)
Reading edition
It may be proper to mention that, while the formulæ given in the text are those of M. Fresnel, I am responsible for the investigations in the Notes; I have, at the same time, much pleasure in acknowledging my obligations, at various times (about ten years ago), to Mr Edward Sang, and (more recently) to Mr William Swan, for their kind advice on this part of the subject.