Dr A. D. Morrison-Low is Principal Curator,
History of Science and Photography, at National Museums
Scotland, Edinburgh. Her Paper below on the development
of early lighthouse optics first appeared in: Bart Grob
and Hans Hooijmaijers (eds.), Who needs scientific instruments:
conference on Scientific Instruments and their users
(Leiden, 2006), pp89-97.
A. D. Morrison-Low, National Museums Scotland
Allen Simpson, a former colleague, published a paper in
1994 entitled 'François Soleil, Andrew Ross and
William Cookson: the Fresnel Lens Applied'. In it,
he showed how burning lenses evolved into the stepped echelon
optical configuration of the lighthouse lens, and commented
that, although the burning lens might be 'considered part
of the conventional field of scientific instruments, lighthouse
lenses probably would not, even though the only aspect that
differentiates them is the area of application.'
In the beginning, of course, there were no lights. Scotland‘s
coasts were dark and dangerous, especially on the sparsely
populated and windswept Atlantic western shores.
However, from early medieval times most external trade was
eastwards across the North Sea, and small craft made their
way across these relatively calm waters to the greater ports
of Europe, in the Low Countries and the Baltic. But there
were severe natural hazards to be found all the way up the
east coast of Scotland, particularly at the mouths of the
various estuaries around which most of the east coast royal
burghs were located. The royal burghs were the early settlements
that had been granted special privileges by the king, amongst
which was the ability to trade outside the kingdom.
Charting these dangerous coasts remained an inexact science
until the late 17th century. Scotland had of course appeared
in Ptolemy's Geographia, and appeared approximately
in various medieval portolan charts, and seamen's 'rutters','before
being reasonably well outlined by Gerard Mercator in 1564.
During the 16th century, cartographic knowledge was regarded
as the prerogative of princes, and it was not until about
1600, with the flowering of Renaissance thought in Northern
Europe, that this information came to be seen as publicly
available, and especially important for the ordinary navigator.
The first printed sea-atlas, printed in Leiden in 1584
by Lucas Jansz Waghenaer, the Spieghel der Zeevaerdt,
included a chart of the east coast from Bamburgh to Aberdeen.
But it was not until 1681 that a survey, undertaken by Captain
Greenvile Collins, sponsored by the Admiralty and Charles
II, that the British coasts – including the east coast
of Scotland, and Orkney and Shetland - were made available
in a publication entitled Great Britain's Coasting Pilot.
The Scotsman John Adair, who was surveying the east coast
at the same time, did not manage to publish his charts until
Both Collins's and Adair's charts show the dangers of the
eastern approaches, and also illustrate Scotland's earliest
lighthouses. Both Aberdeen and Leith (Edinburgh's port on
the Firth of Forth – 'firth' being the Scots word
for estuary) had beacons – braziers kept alight at
night - at their harbour entrances from at least the 15th
at Leith was illustrated by Greenvile Collins, and was a
welcoming sight to mariners who had navigated up the Forth.
But it was the unlit hazards that the increasing numbers
of seafarers wished to anticipate.
The first major obstacle in the Firth of Forth –
upon which Leith lies, gateway to the capital – is
a rocky island named the Isle of May. It is about five and
a half miles south-east of Anstruther, and about eleven
miles north-west of North Berwick: its long axis runs from
north-west to south-east, it is about a mile in length and
at its widest is about a third of a mile.
It is characterised in a recent architectural guide as a
'Bare island in the Firth of Forth, the home of monks in
the Middle Ages, of lighthouse keepers since the 17th century'.
Some local Fife landowners grouped together to petition
the Scots government for the provision of a light, and a
simple grate on a tower was set up in 1636. This was a two-storey
building, with the grate on the top; after 1786 there was
a rope and pulley windlass which was used to haul up the
pans of coal.
By this time, the Northern Lighthouse Board had been formed,
and had placed its first four lights strategically on the
sea routes around Scotland's stormy and dangerous northern
and western coasts: at Kinnaird Head in 1787; at the Mull
of Kintyre, at North Ronaldsay in Orkney, and at Eilean
Glas on Scalpay on the Minch (the narrow sea passage between
the Hebridean islands and the mainland) in 1788. This government
board came into being after the Union of the Parliaments
in 1707, and had – and still has – responsibility
for the lighthouses of Scotland and the Isle of Man. In
England, the Brethren of Trinity House has had that responsibility
since at least the 13th century; and in Ireland, the Commissioners
of Irish Lights was formed from previous authorities in
And now to the influence of scientific instruments: clearly
these were not required when lighthouses used coal-fired
grates of the type encountered on the Isle of May. Neither
were instruments in any way influential in the lighting
of one of the more revolutionary design for lighthouses,
that of the fourth tower to stand on the dangerous Eddystone
reef in the English Channel, built by John Smeaton in 1756.
Despite Smeaton serving an apprenticeship as an instrument
maker in London, his form of lighting was no more dramatic
than a chandelier fitted with twenty-four candles –
which it has been calculated was visible at about five miles.
By the time the Northern Lighthouse Board had begun to
build their first four defining towers around the Scottish
coasts, they were employing Thomas Smith, a lighting engineer,
to assist them in their task. Smith, born into a seafaring
family across the Firth of Tay from the important port of
Dundee in 1752, had lost his father by shipwreck when merely
a child. He was then apprenticed to a Dundee metal-worker,
and emigrated to Edinburgh just as that city enlarged itself
in 1770. His oil lamp business expanded and by 1787 he had
the contract to provide street lighting for the Old and
subsequently the New Towns of Edinburgh. By 1807, he had
expanded this to light the streets of Perth, Stirling, Ayr,
Haddington and Aberdeen. The Northern Lighthouse Board appointed
Smith as their Engineer in January 1787, six months after
his proposal that reflector lamps be substituted for the
coal light on the Isle of May was rejected by Edinburgh's
Chamber of Commerce.
Smith was not the Northern Lighthouse Board's first choice:
they had first invited Ezekiel Walker of King's Lynn, the
designer of improved lighting at Hunstanton Lighthouse on
the Norfolk coast, to put up their first four lights. Instead,
after Walker had declined this invitation, Smith was sent
to Norfolk to learn about the particular problems involved
in lighthouse illumination.
For the next twenty years, starting with the conversion
of Kinnaird Castle at Fraserburgh into a lighthouse, Thomas
Smith was responsible for the illumination of thirteen lighthouses,
mostly at remote locations.
Smith improved the intensity of illumination by reflection
(or the 'catoptric' system). He developed and made arrays
of parabolic reflector oil lamps of his own design. These
had a light source at their focus, and a curved reflector
formed of small pieces of mirror set in plaster, which focused
the light into a parallel beam which could be rotated in
a horizontal plane.
Nonetheless, these proved to be much less efficient than
the silvered-copper reflectors already in use in France,
and which were soon installed elsewhere with Argand lamps
with glass chimneys.
After 1801, Smith and his son-in-law Robert Stevenson (who
was to succeed him in business and at the Northern Lighthouse
Board) began to make and install Argand lamps and silvered-copper
reflectors, starting at another lighthouse on an island
in the Firth of Forth, at Inchkeith in 1804. However, the
glass facet reflectors continued to be used by the Northern
Lighthouse Board in lights elsewhere until the 1820s.
The Argand lamp was the invention of Aimé Argand,
a Swiss in Geneva, who developed in the 1780s a relatively
smokeless oil lamp which gave a steady flame and a more
intense light than previously achieved. His lamp had two
vertical concentric tubes of thin brass, which held between
them a cylindrical wick. Air passed through the tube, ensuring
that both sides of the lighted wick had an even temperature
and good combustion. A glass chimney channeled the airflow
to give further brilliance, and the wick's height could
also be finely adjusted. By about 1815 this lamp could produce
the same amount of light as seven or eight candles. Initially,
this increased the demand for sperm oil – the oil
from the sperm whale – to such an extent that the
French resorted to colza oil, which uses the seed of a wild
cabbage. By 1845, the British had turned to this, too.
Meantime, Smith had retired from lighthouse illumination
and construction, handing over this side of the business
to his step-son and son-on-law Robert Stevenson in 1797,
when the younger man was aged twenty-five; Robert Stevenson
formally succeeded him as Engineer to the Northern Lighthouse
Board in July 1808. He had attended natural philosophy classes
of both Professor John Anderson at Glasgow University and
Professor John Robison at Edinburgh University, although
he did not take a degree. He had also served practical apprenticeships
in metalwork and lamp installation, and throughout his life
he maintained an acquaintance with Edinburgh's intelligentsia,
and belonged to many of the scientific societies which flourished
at that point.
In an attempt to increase the intensity of the beam, spherical
reflectors had been introduced in some French lighthouses
in the 1780s and 1790s, but these had proved problematic.
At Cordouan, near Bordeaux, the famous and ancient lighthouse
had been the scene of a series of practical investigations
and tests, involving French philosophers, clockmakers and
scientists. Both the scientist Jean-Charles Borda and the
instrument maker Etienne Lenoir were concerned, producing
a rotating apparatus with spherical reflectors; however,
mariners found these inadequate. When Léonor Fresnel
replaced them with a revolving dioptric apparatus in 1823
(using lenses instead of reflectors), he concluded that
the original reflectors had been inadequately set up.
Robert Stevenson developed his own metal parabolic reflector
in about 1810. To ensure accuracy, Stevenson had the reflector
curves drawn by Professor John Leslie and their moulds made
by the Edinburgh optician Alexander Adie. This type of optical
apparatus was supplied by various brass founders, including
James Milne of Edinburgh, to many British and colonial lighthouses
between 1810 and 1880.
One set of revolving parabolic reflectors was installed
in 1811 in Robert Stevenson's most important lighthouse,
the Bell Rock, and was removed in 1843 to Newfoundland,
where it continued in service until after 1872.
Apparently the Scottish reflectors were plated so thickly
that they could afford the loss of silver through cleaning,
and thus gave long service. The metallic silver was recovered
by collecting and burning the cleaning cloths.
They were also set up using a gauge, which ensured that
the lamp – and thus the beam - was always set up correctly
It is unclear whether gauges of this type have survived.
However, one survival (initially in the Stevenson family,
and now in the National Museums of Scotland) is a device
which can set a series of reflectors on a frame for a fixed
light (not a revolving light, such as was that at the Bell
Rock). "In fixed lights", wrote Alan
Stevenson, "it is necessary, in order to approach
as near as possible to an equal distribution of the light
over the horizon, to place the reflectors, with their axes
somewhat less than that of the divergence of the reflected
The instrument is signed by Adie & Son, and was made
for the Stevenson firm.
It is inappropriate to linger here over the building of
the Bell Rock lighthouse and the engineering problems that
were solved there by Robert Stevenson; instead, we shall
examine the next form of illumination: through prisms and
glass. Allen Simpson's paper, referred to earlier, discussed
in some detail the beginnings of this technology: how Robert
Stevenson acquired two square-framed panels from the Parisian
optician François Soleil of the type being used at
Cordouan at about the same time that a 'burning glass' was
ordered from the same maker by the University of Edinburgh.
A few years later, Fresnel developed a smaller cylindrical
lens, also constructed by Soleil, as a harbour light. Robert
Stevenson and the Northern Lighthouse Board were greatly
impressed by the results they obtained from these lenses;
however, the entire affair was muddied by a bitter argument
of priority of invention over the Fresnel lens, by Sir David
Brewster, a scientific figure who commanded respect across
Early in 1831 a committee of the Northern Lighthouse Board
was formed to compare the merits of lenses and reflectors,
following a report by Stevenson on the lenses. Two years
later, there were some practical experiments, which took
place on three consecutive nights in February 1833. Under
the direction of young Alan Stevenson and his father Robert,
light was shone through lenses and by reflectors from temporary
buildings put up near the coast on Gullane Hill, about twelve
miles from Edinburgh, and their effects were observed from
Calton Hill in central Edinburgh by some Fellows of the
Royal Society of Edinburgh, including Sir David Brewster,
as well as the lighthouse committee.
Everyone present was impressed by the results. Robert Stevenson
found that light from the lens was equal to seven to nine
reflectors; but Brewster went further and demanded that
all Scottish lighthouses should immediately be furnished
with lenses. Stevenson argued for caution, as many of Brewster's
proposals were extremely expensive – not least the
crippling Excise dues on the optical glass. But Brewster
reacted badly, publishing anonymously a savage article in
the Edinburgh Review (a widely-read political journal),
and this led almost immediately to a major public parliamentary
This enquiry resulted in a number of recommendations, mostly
to do with organisation and finance, which need not detain
us here. Of more significance to the technology, Robert
Stevenson's eldest son Alan was sent off immediately to
France by the Commissioners to inspect the French lights,
and to meet Léonor Fresnel, successor to his famous
brother as secretary of the Commission des Phares.
He also spent time in the workshops of the instrument-maker
François Soleil, the clockmaker Pierre Basile Lepaute,
and the lamp-maker Bordier Marcet, pupil and successor of
As Alan Stevenson was to write himself:"Although
many experiments were made with lenses during the winter
of every succeeding year [to 1825], it was not until the
spring of 1834 that the Commissioners took decisive steps
for deciding the question as to the comparative merits of
the catoptric and dioptric system, by sending me, in the
spring of 1834, on a mission to Paris, with full power to
take such steps for acquiring a perfect knowledge of the
dioptric system, and forming an opinion on its merits, as
I should find necessary. The singular liberality with which
I was received by M. Léonor Fresnel, brother of the
late illustrious inventor of the system, and his successor
as the Secretary of the Lighthouse Commission of France,
afforded me the means of making such a report on my return,
as induced the Commissioners to authorise me to remove the
reflecting apparatus of the revolving light at Inchkeith,
and substitute dioptric instruments in its place. This change
was completed, and the light exhibited on the evening of
1st October 1835; and so great was the satisfaction which
the change produced, that the Commissioners immediately
instructed me to make a similar change at the fixed light
of the Isle of May, where the new light was exhibited on
the 22nd September 1836."
And as R.W. Munro states: "The Commissioners now
became the pioneers of the dioptric system in the British
Both Inchkeith in 1835 and the Isle of May the following
year had improved refractors made by Messrs Cookson of Newcastle,
business associates of Robert Stevenson, with the effect
of tripling the brightness of the lights. Trinity House
(the English lighthouse board) soon employed Alan Stevenson
to direct the construction of their first revolving dioptric
light for Start Point in Devon in 1836.
But his greatest challenge was to be the building of a rock
lighthouse at Skerryvore, an Atlantic-lashed jagged rock
set among lesser reefs 12 miles west of Tiree. It lies between
the Hebrides and the north Irish coast, near a new shipping
highway opening westwards towards North America.
Alan Stevenson's account of Skerryvore, which is another
epic comparable with his father's at the Bell Rock, discusses
many of the problems he encountered and solved, but here
we will focus on one particular and crucial issue: the correct
setting of the Fresnel lenses and the accurate centring
of the lamp itself within the lenses. In his account he
gives full credit to the maker of the optics, which was
the Parisian workshop of François Soleil; and to
the maker of the machinery, including the lampwork, by the
Edinburgh brass founder, John Milne.
Having learned much from his French visit, the Oxford
Dictionary of National Biography states that:
"Skerryvore's revolving dioptric apparatus was
the most advanced in the world at that time, with prismatic
rings instead of mirrors below the central belt, thus extending
the improved dioptric effect. Stevenson further improved
its efficiency by introducing inclined astragals into the
lantern. His improvements to the dioptric system, which
included the conversion of Fresnel's narrow lenses in fixed
systems into a truly cylindrical drum, led to its wider
But the task of assembling the delicate but very heavy
component lens panels into a complete rotating optic was
complex. The site, high in the lighthouse lantern, was very
cramped and comparatively inaccessible; and not only did
the tall optic have to remain in balance during construction;
its shape also had to be adjusted within narrow margins
to ensure that the optimum optical performance was achieved.
Alan Stevenson's diagrams show how the problem was resolved
– using specially designed instruments, engineered
for Stevenson by John Adie, to align the panels as tension
was taken up at their boundaries.
Stevenson's diagrams demonstrate, as do the surviving instruments
which correspond to them, that his ideas have been elegantly
solved by John Adie. The first instrument (Figure 1) is
to ensure that the lenses meet at 'the proper horizontal
angle, so that their axes shall meet with the proper inclination
in the focus'.
The second (Figure 2) ascertains the verticality of the
main lenses, or sets the subsidiary lenses or mirrors at
the required angle, with a spirit level; so this is in fact
a special clinometer.
The third, and final example (Figure 3), is a device which
tests the true position of the lamp itself in the context
of the lenses.
It acts as a radius, with F being the central burner, 'while
its point A touches the centres of the lenses. At B is a
graduated slide [now seized], which allows the radius arm
to be lengthened or shortened to suit various different
focal distances.' The dotted outline shows the device being
moved on to an adjacent lens.
Without these scientific instruments, constructed for just
this specific purpose, the complex lenses of Skerryvore
could not have shone out with clarity over the Atlantic
Instrument to ensure Fresnel lenses
are correctly focused, Adie & Son, Edinburgh, c.1840
(NMS T.1958.49). Designed by Alan Stevenson for use at Skerryvore,
Instrument for ensuring that the vertical
lenses or mirrors are set at the correct angle, by Adie
& Son, Edinburgh, c.1840 (NMS T.1958.48). Designed by
Alan Stevenson for use at Skerryvore, 1844.
Instrument to test the true position
of the lamp in the context of Fresnel lenses (NMS T.1958.56).Designed
by Alan Stevenson for use at Skerryvore, 1844.
As it says in a maddening piece of doggerel that all British
schoolchildren can recite: 'It was a dark and stormy
night, and the captain said to the mate, "Tell me a
story"; so the mate began. It was a dark and stormy
night . . .', and so on, ad infinitum.
In the paper mentioned at the beginning of this piece, Allen
"The fact that precision apparatus is an integral
part of many types of discipline emphasises the necessity
for instrument historians to justify the relevance of the
specialism to wider audiences. And it is often in the literature
and archives of other disciplines (in this case civil engineering)
that valuable evidence can be found that illuminates the
capabilities and limitations of the industrial concerns
that are central to the world of precision instruments."
The allotted time is over, and, as ever, the exercise has
raised more questions than it has answered. Although the
night was dark and stormy, the links between the instrument
maker and the Northern Lights was clearly a strong one,
and together they illuminated the seas. In due course, I
hope to find out more.
References and acknowledgments
My thanks to Chris Henry, Director of the
Museum of Scottish Lighthouses, Fraserburgh, for access
to trade literature obtained from the Northern Lighthouse
Board; to my former colleague, Dr Allen Simpson, for his
help and advice; and to the Library of the National Museums
of Scotland for their unfailing swiftness in supplying me
with books; and the photographers for their help in providing
me with suitable images.
 A.D.C. Simpson, 'François Soleil,
Andrew Ross and William Cookson: the Fresnel Lens Applied',
Bulletin of the Scientific Instrument Society, No. 41 (1994),
16-19; quotation on p.18.
 Much of the information given in the
next few paragraphs is based upon a paper written by A.D.
Morrison-Low and A.D.C. Simpson, ' “For Those in Peril
on the Sea”: Scottish Sea-Marking to 1787', in Jan
Parmentier (ed.), Navigating the Northern Seas (forthcoming).
 Derek Hall, Burgess, Merchant and Priest:
Burgh Life in the Scottish Medieval Town (Edinburgh, 2002),
 D.G. Moir (ed.), The Early Maps of
Scotland to 1850 third edition, 2 vols. (Edinburgh, 1983),
 P.D.A. Harvey, Maps in Tudor England
(London, 1993), 7; see also David Buisseret, The Mapmakers'
Quest: Depicting New Worlds in Renaissance Europe (Oxford,
 Moir, op. cit. (4), II, 1-2.
 Sir James Marwick (ed.), Extracts from
the Records of the Burgh of Edinburgh, 1528-1557 (Edinburgh,
1871), 275-6, 289, 295, quoted by R.W. Munro, Scottish Lighthouses
(Stornoway, 1979), 22-23; John Stuart (ed.), Extracts from
the Council Register of the Burgh of Aberdeen, 1398-1570
(Aberdeen, 1844), 361-2, also quoted by Munro, op. cit.
 Greenvile Collins, Great Britain's
Coasting Pilot (London, 1776), 23. Collins's book was published
in eleven editions between 1693 and 1792.
 W.J. Eggeling, The Isle of May (Edinburgh
and London, 1960), 5.
 John Gifford, The Buildings of Scotland:
Fife (London, 1988), 320.
 Eggeling, op. cit. (9), 33-34.
 For general accounts of each of these
boards and their work, see D.B. Hague and R. Christie, Lighthouses:
their Architecture, History and Archaeology (Llandysul,
1975); K. Sutton-Jones, Pharos (Salisbury, 1985); D. Alan
Stevenson, The World's Lighthouses before 1820 (Oxford,
1959). The most authoritative account of the work of the
Northern Lighthouse Board is Munro, op. cit. (7). See also,
Martin Boyle, Lighthouses: Four Countries – One Aim
 John Smeaton, A Narrative of the Building
and Description of the Construction of the Edystone Lighthouse
with Stone … (London, 1791).
 Jean Leslie and Roland Paxton, Bright
Lights: The Stevenson Engineers 1752-1971(Edinburgh, 1999),
 Stevenson, op. cit. (12), 291-2.
 For the history of the lighthouse
at Kinnaird Head see Sarah Swallow, Lighthouses of Scotland:
Kinnaird Head (Southampton, 1998); Thomas Smith's 13 lights
(and those of the individual Stevensons) can be found listed
in Appendix 2 of Leslie and Paxton, op. cit. (14), 191-5.
 [Thomas Smith], 'Reflectors for light-houses',
Encyclopaedia Britannica, fifth edition (Edinburgh, 1817),
XVII, 671; however, for a discussion about the claim whether
this was invented by Smith, or by Walker, see Leslie and
Paxton, op. cit. (14), 23.
 Stevenson, op. cit. (12), 61-71; 288-90.
 Leslie and Paxton, op. cit. (14),
22-23; Robert Stevenson, 'Inchkeith', Edinburgh Encyclopaedia
22 vols. (Edinburgh, 1808-30), XII, 9-12; and 'Lighthouse',
ibid., XIII, 1-18.
 Stevenson, op. cit. (12), 61-62. For
a comprehensive history, see Michael Schrøder, The
Argand Burner: its origin and Development in France and
England 1780-1800 (Odense, 1969).
 Leslie and Paxton, op. cit. (14),
 Stevenson, op. cit. (12), 187-200.
 Stevenson, op. cit. (12), 294-5.
 Stevenson, op. cit. (12), 224.
 Stevenson, op. cit. (12), 284.
 Alan Stevenson, Account of the Skerryvore
Lighthouse, with Notes on the Illumination of Lighthouses
(Edinburgh, 1848), 226.
 Stevenson, op. cit. (26), 230.
 Simpson, op. cit. (1); for Brewster,
see A.D. Morrison-Low and J.R.R. Christie (eds.), 'Martyr
of Science': Sir David Brewster, 1781-1868 (Edinburgh, 1984).
 Munro, op. cit. (7), 99-101.
 Munro, op. cit. (7), 102-7; [David
Brewster], 'Parliamentary Report on Lighthouses', Edinburgh
Review, 61 (1835), 221-241; note, signed by Alan Stevenson,
ibid., 526-8; reply [Brewster?], ibid., 528-31.
 Munro, op. cit. (7), 107.
 Alan Stevenson, A Rudimentary Treatise
on the History, Construction, and Illumination of Lighthouses
(London, 1850), 6.
 Munro, op. cit. (7), 110.
 Munro, op. cit. (7), 109-111.
 Stevenson, op. cit. (26), 22.
 Stevenson, op. cit. (26), 177.
 Roland Paxton, 'Alan Stevenson', Oxford
Dictionary of National Biography (Oxford, 2004).
 T.1958.56. All of these instruments
now survive in the collections of the National Museums of
Scotland, where they were first adequately identified by
my colleague Allen Simpson some years ago.
 Stevenson, op. cit. (26), 295-6.
 Edward Bulwer Lytton, Paul Clifford
 Simpson, op. cit. (1), 18.