CONTENTS.

PART I.
ACCOUNT OF SKERRYVORE LIGHTHOUSE.
Page
Introduction — Constitution of the Lighthouse Board — Lights established since 1821 — Improvements in the mode of illumination — DioptricLights — Beacons and Buoys,[9]
CHAPTER I.
Topographic notice of the Skerryvore Rock,[19]
CHAPTER II.
Preliminary arrangements and works, including survey of the rocks, and opening of quarries from 1834 to 1837 — Survey of the Skerryvorerocks — Disadvantages of Tyree — Pier and workyard at Hynish, Tyree — Quarries at Hynish — Skerryvore Committee appointed,[37]
CHAPTER III.
On the construction of Lighthouse Towers,[45]
CHAPTER IV.
OPERATIONS OF 1838.
Temporary Barrack on Rock — Tools and machinery — Steam Tender for the works —Employment and wages of workmen — Progress of the outfit for theseason’s operations — Embark for Skerryvore — Lay down moorings, and try to land on the Rock —Driven to Mull — First day’s work on the Rock — Shipment of materialsat Glasgow and Greenock — Reach Tyree — Driven to Mull — Return to Tyree — First good day’s workon the Rock — Sudden gale and great peril to the vessels — Reach Hynishin safety — Detained by bad weather four days at Hynish — Return to the Rock and have six days ofgood weather — Erection of the pyramid of the wooden barrack — Modeof determining the length of the beams, and the sites for their fixtures — Pyramid completed — Modeof living while erecting the barrack — Shoals of Medusæseen — Driven by a gale to Mull — Return to Hynish and are driven to Coll — Return to the Rock —Driven to Tyree — Return to the Rock — Horizontal braces fixed — Drivento Mull — Heavy gale — Timber cast on Tyree —Return to Rock and further progress of barrack — Last day’s work onRock this season — Precaution for the benefit of shipwrecked seamen — View from top of pyramid —Destruction of the barrack during a gale — Letter from MrHogben — Proceed to Skerryvore — State in which the Rock was found — Cause of the destruction ofthe barrack — Preparations for a new barrack — Works at Hynish — Hynishquarries,[71]
CHAPTER V.
OPERATIONS OF 1839.
Shipping station and pier at Hynish — Granite quarries in Mull — Observations on the quarrying of granite — Dressing of the Lighthouseblocks — Excavation of foundation for the Lighthouse Tower on the Skerryvore Rock — Fitting up of the second barrack on the Rock — Sudden death of GeorgeMiddlemiss — Wharf and landing-place on the Rock — Ring-bolts, water-tanks, andrailways — Incidents of the season — Effects of a gale from the south-west — Mutiny ofthe crew — Near approach of the vessels to the Rock, and other circumstances shewing the importance of a Light on the Skerryvore,[107]
CHAPTER VI.
OPERATIONS OF 1840.
Hynish workyard — Hynish pier — The Rock — Life in the barrack —Foundation-pit — Landing of the materials on the Rock — Laying the first stone,[140]
CHAPTER VII.
OPERATIONS OF 1841.
Hynish workyard — The Rock — The waves — Colours of the breaking waves — The seals,[151]
CHAPTER VIII.
OPERATIONS OF 1842.
State of the Rock in Spring of 1842 — Commencement of Rock operations — Last stone — The Lantern,[163]
CHAPTER IX.
CONCLUDING OPERATIONS AND EXHIBITION OF THE LIGHT.
Harbour works — Bo Pheg beacon — Light-keepers’ and seamen’s houses — Concluding works on the Rock, such as pointing, &c. — Interiorfittings of the Tower — Light-room apparatus, and first exhibition of the Light — Removal of the barrack from the Rock — Expense,[169]
PART II.
NOTES ON THE ILLUMINATION OF LIGHTHOUSES, WITH SHORT NOTICES OF THEIR HISTORY, [181].
Early history, [181] — Colossus of Rhodes, [182] — Pharos of Alexandria,[183] — Coruna Tower, [187] — Lighthouse at the mouth of the Quadalquivir, [188] — AncientPhari in Britain, [188] — Tour de Corduan, [189] — Eddystone, [189] — Bell Rock,[192] — Carlingford, [194] — Iron lighthouses, [194] — Early modes of illumination,[195] — Flame, [196] — Drummond and Voltaic Lights, [199] — Mr Gurney’s Lamp,[200] — Argand Burners, [200].
CATOPTRIC SYSTEM OF LIGHTS, [204].
Application of Paraboloidal Mirrors, [205] — Reflection, [207] — Paraboloidal Mirrors,[209] — Divergence of Paraboloidal Mirrors, [212] — Effect of Paraboloidal Mirrors, [217] — Power ofditto, [218] — Manufacture of reflectors, [218] — Testing of mirrors, [219] — Argand Lamps used inreflectors, [220] — Arrangements for raising or lowering the Argand wick, [222] — Flowing of the lamp,[223] — Placing the lamp in the focus, [226] — Distinctions of Catoptric Lights, [227] — Colouras a distinction for lights, [229] — Arrangement of reflectors on the frame, [230] — Bordier Marcet’s reflectors,[232] — Fanal sidéral, [232] — Fanal à double effet, [234] — Fanal à double face,[236] — Mr Barlow’s spherical mirrors, [237] — Captain Smith’s mirrors in the form of a parabolic spindle,[238].
DIOPTRIC SYSTEM OF LIGHTS, [239].
Early history of Lighthouse lenses, Condorcet, Buffon, Brewster, Fresnel, [239] — Refraction,[242] — Lenses, [245] — Spherical aberration, [248] — Fresnel’s formulæ for annular lenses,[249] — Testing lenses, [255] — Divergence of lenses, [256] — Illuminating power of lenses,[257] — Arrangement of lenses in a Lighthouse, [258] — Pyramidal lenses and mirrors, [259] — Curvedmirrors, [260] — Cylindric refractors of fixed Lights, [263] — Application of crossed prisms to cause flashes,[264] — True cylindric form given to refractors, and other improvements in their construction, [264] — Catadioptriczones, the mode of computing their elements, &c., [267] — Testing of zones, [282] — Framing of zones,[286] — Mechanical lamp, [286] — Height of flame of mechanical lamp, [289] — Position of flamein reference to focus, [290] — Working of the pumps, [291] — Choice of focal point for various parts of apparatus,[292] — Choice of a focal point for zones, [292] — Application of spherical mirrors to fixed Dioptric Lights,[293] — Arrangement of Dioptric apparatus, [293] — Arrangement of Dioptric apparatus in Lightroom,[294] — Power of Dioptric instruments, [298] — Orders of French Lights, [298] — Distinctions ofDioptric Lights, [299] — Comparison of Dioptric and Catoptric apparatus for revolving lights, [301] — Comparison forfixed lights, [303] — Summary of views as to two systems for revolving lights,[306] — Summary of views as to two systems for fixed lights, [306] — Advantages and disadvantages of both systems undercertain circumstances, [308] — Distinctions of the Dioptric Lights and the application of coloured media, [311] — CaptainBasil Hall’s proposal for fixed lights, [313] — Effects of rapid motion on the power of lights, [315] — Connection ofexperiments with irradiation, [320].
VARIOUS GENERAL CONSIDERATIONS CONNECTED WITH LIGHTHOUSES, [320].
Masking Lights, [320] — Double Lights, [322] — Leading Lights,[323] — Distribution of Lights on a coast, [325] — Height of Lighthouse Tower, and its relation to range of light,[328] — Diagonal Lantern, [330] — Glazing of Lantern, [331] — Ventilation of Lanterns,[331] — Arrangements and Management of a Lighthouse, [334] — Cleansing of apparatus, [335] — Modeof measuring relative power of lights, [336] — More accurate comparison of intensity of lights, [338] — Floating Lights,[346] — Beacons and Buoys, [347].

APPENDIX.

[1.]Table of Co-ordinates of Hyperbolic Column.
[2.]Notes on the Making of Paraboloïdal Mirrors.
[3.]Notes on the Grinding and Polishing of Dioptric Instruments for Lighthouses.
[4.]Table of the Elements of the Catadioptric Zones for Lights of the first order in the system of Augustin Fresnel.
[5.]Notice to Mariners of the Exhibition of the Skerryvore Light.
[6.]Detailed Account of the Expense of the Skerryvore Lighthouse.
[7.]Excerpts from Account of Experiments on the Force of the Waves of the Atlantic and German Oceans, by Thomas Stevenson, F.R.S.E., Civil Engineer.
[8.]Annual List for 1848 of Lighthouses, Beacons, and Buoys, in the District of the Northern Lights Board.
[9.]Annual Report by the Secretary as to the Income and Expenditure of the Northern Lights Board for 1846.
[10.]Instructions to the Light-keepers in the Service of the Commissioners of the Northern Lighthouses.

PLATES.

[I.]Chart shewing the situation of the Skerryvore Lighthouse.
[II.]Chart shewing the position of the Skerryvore Rocks and foul ground.
[III.]Plans of the Skerryvore Rock at high and low water of spring tides.
[IV.]Curves for Lighthouse Towers — Marine Dynamometer.
[V.]Barrack of timber on the Skerryvore Rock.
[VI.]Details of fixtures of timbers at the top of the Timber Barrack.
[VII.]Elevation of Skerryvore Lighthouse.
[VIII.]Section of Skerryvore Lighthouse.
[IX.]Balance Crane used at Skerryvore.
[X.]Plan shewing the Lighthouse Establishment of Barracks, Harbour, &c., at Hynish, in the Island of Tyree.
[XI.]Elevation and Section entrance to Dock at Hynish.
[XII.]Plan and Section of Annular Lens.
[XIII.]Perspective Elevation of Revolving Dioptric Apparatus of First Order.
[XIV.]Plan of Revolving Dioptric Light of First Order, with Mirrors.
[XV.]Vertical Section of fixed Dioptric Lights of First Order, with Mirrors.
[XVI.]Elements of Concave Mirrors for Dioptric Lights of First Order, and arrangement on the Frame.
[XVII.]Perspective View of Fixed Dioptric Light of First Order, with Catadioptric Zones.
[XVIII.]Vertical Section of Fixed Dioptric Light of First Order, with Catadioptric Zones.
[XIX.]Vertical Section of Catadioptric Light of Fourth Order, with Framing.
[XX.]Elevation of Mechanical Lamp for Dioptric Lights of First Order.
[XXI.]Enlarged Views of Oil-Pumps of Mechanical Lamp.
[XXII.]Enlarged Views of Oil-Pumps of Mechanical Lamp.
[XXIII.]Details of Clock-work of Mechanical Lamp.
[XXIV.]Details of Clock-work of Mechanical Lamp.
[XXV.]Flame of Mechanical Lamp of First Order at full size.
[XXVI.]Elevation of Diagonal Lantern, and details of Astragals.
[XXVII.]Elevation of Ardnamurchan Lighthouse.
[XXVIII.]Plan of Ardnamurchan Lighthouse.
[XXIX.]Lines of a Floating Light Vessel belonging to the Corporation of Trinity House of Deptford Strond.
[XXX.]Elevation of Covesea Skerries Beacon.
[XXXI.]Details of Covesea Skerries Beacon.
[XXXII.]Elevations and Sections of Stone and Iron Beacons.
[XXXIII.]Elevations of Buoys.

ERRATA.

Page52,line 8, for Redelet read Rondelet
...178,line 6, for L.93,306:8:10 read L.86,977:17:7
...292,line 30, for radius rector read radius vector
...294,line 13, for give read gives
...329,line 3, for earth read sea
...347,line 29, for Plate XXXII., read Plate XXX.,