Transcriber’s Notes Text transcribed between _underscores_ represents text printed in italics in the source doument. Small capitals have been replaced with ALL CAPITALS. ^{text} and _{text} represent superscript and subscript text resepecively. Text between ~tildes~ represents marginalia. [Illustration: SKERRYVORE LIGHTHOUSE.] ACCOUNT OF THE SKERRYVORE LIGHTHOUSE, WITH NOTES ON THE ILLUMINATION OF LIGHTHOUSES; BY ALAN STEVENSON, LL.B., F.R.S.E., M.I.C.E., ENGINEER TO THE NORTHERN LIGHTHOUSE BOARD. [Illustration: ·NORTHERN LIGHTHOUSES· IN SALUTEM OMNIUM.] “ΥΠΕΡ · ΤΩΝ · ΠΛΩΙΖΟΜΕΝΩΝ” _Inscription on the Ancient Pharos of Alexandria._ BY ORDER OF THE COMMISSIONERS OF NORTHERN LIGHTHOUSES. ADAM AND CHARLES BLACK, NORTH BRIDGE, EDINBURGH. LONGMAN AND CO., LONDON. MDCCCXLVIII. PRINTED BY NEILL AND COMPANY, EDINBURGH. PREFACE. I am unwilling to dismiss the following pages from my hands without saying a few words in extenuation of the defects which they contain. My chief plea in defence is, that the preparation of this _Account of the Skerryvore Lighthouse_, and the _Notes on the Illumination of Lighthouses_ which follow it, was not chosen or assumed by me, but was a task imposed by the express desire of the Lighthouse Board, to whose enlightened and liberal views the Mariner owes the erection of the Lighthouse itself. My labours were also continually interrupted by the urgent calls of my official duties; and, on several occasions, I was forced to dismiss unfinished chapters from my mind for a period of several months--circumstances which, I hope, will in some measure account for the desultory character of the performance, the disproportion of some of its parts, and more especially for repetitions and perhaps omissions which would otherwise have been quite unpardonable. Having said thus much by way of apology for this Volume, I must acknowledge my many and great obligations to my Father who preceded me as Engineer to the Board of Northern Lighthouses, and of whose experience, as the Architect of no fewer than twenty-five Lighthouses, including that of the Bell Rock, I had the full benefit during the erection of the Skerryvore Lighthouse. To the generosity of my esteemed friend, M. LEONOR FRESNEL, I owe all that I know of the Dioptric System of Illumination, invented by his late illustrious Brother; but this general acknowledgment will not supersede the necessity of frequent repetitions of my obligations to him, as occasion offers, in the course of these pages. I have also derived much assistance, as a careful reader will easily trace, from the valuable little work of M. PECLET, entitled _Traité de l’Eclairage_. There are, besides, many other obligations, which I cannot attempt to acknowledge individually, but which those, who kindly conferred them, well know how much I value. * * * * *