Presentation on the history of Lighthouses

1. L I G H T H O U S E S
Signaling, Aiding Navigation

2. C O N T E N T S :
• What are Lighthouses?
• How do they work?
• Lens / Light Type?
• Light Characteristics
• Lighthouses known as...
• What do they do?
• Early Light Materials
• Fresnel Lens
• How do you direct the light out to sea?
• Main Function?
• Main Use?
• What kind of Lighthouse is on shore?
• Lantern Room
• Aids to Navigation

3. W H AT A R E L I G H T H O U S E S ?
Lighthouses are:
• focused beacons of light
• NOT to illuminate,
• but to SIGNAL

4. H O W D O T H E Y
W O R K ?
• Lighthouses have a LIGHTSOURCE,
• That can be fixed with:
• a ROTATING lens
• Or
• A FLASHING Lens.
• Then the light beamed seawards.

5. L E N S / L I G H T
T Y P E ?
• Fresnel Lens
• 1800's

6. L I G H T
C H A R A C T E R I S T I C
• The beamed light creates something
known as a Light Characteristic.
• This identifies the light type to anyone out
at sea.
• It can be a communication code,
indicating the shore nearby, or rocks or
dangerous seabed areas to those at sea
coming inwards.

7. L I G H T H O U S E S A R E
A L S O K N O W N A S :
L I G H T S O N
S H O R E !
They help sailors navigate the ocean and
the surrounding areas, safely.

8. E A R LY L I G H T H O U S E S
M AT E R I A L S ?
• Early lighthouses used wood and real fires
as
beacon lights in the early 1800's.
• These were NOT ideal, as to transport the
fuel up the spire tower everyday cost a lot of
manpower and energy.

9. E A R LY
L I G H T H O U S E S
M AT E R I A L S ?
• Switched to:
• candles
• gas lamps
and
• oil lamps

10. E A R LY
L I G H T H O U S E S
M AT E R I A L S ?
• DISADVANTAGES?:
• Firelight doesn't burn that bright
&
• Safety Hazzard

11. S W I T C H E D T O ?
ELECTRICITY

12. S W I T C H E D T O ?
ELECTRICITY:
• Safer
• Brighter
• Popular Use
• (What most Lighthouses use today)

13. H O W D O Y O U
D I R E C T T H E
L I G H T O U T T O
S E A ?
• Up to the 1800's,
REFLECTORS were
used to direct light out
onto sea.

14. H O W D O Y O U
D I R E C T T H E
L I G H T O U T T O
S E A ?
• Up to the
1800's, REFLECTORS were
used to direct light out onto sea.
• Light could be further focused us
ing a lens in front of the light
source.

15. H O W D O Y O U
D I R E C T T H E
L I G H T O U T T O
S E A ?
Issue?
• Need a HUGE lense

16. H O W D O Y O U
D I R E C T T H E
L I G H T O U T T O
S E A ?
Elegant invention and solution?
• Fresnel lens

17. H O W D O Y O U
D I R E C T T H E
L I G H T O U T T O
S E A ?
• Solution?
• Fresnel lens

18. H O W D O Y O U
D I R E C T T H E
L I G H T O U T T O
S E A ?
• Solution?
• In 1820's, Augustin-Jean Fresnel
invented a revolutionary and elegant
solution

19. H O W D O Y O U
D I R E C T T H E
L I G H T O U T T O
S E A ?
• Solution?
• Light is refracted at the point at which
it passes, from 1 medium to another.
• Lamp Lens = air to glass, and back to
air
• Curve of the lens = desired direction
• Fresnel's Soultion? =
• cut away the rest of the lens

20. H O W D O Y O U
D I R E C T T H E
L I G H T O U T T O
S E A ?
• Result?
• Curve Surface
• Excess material discarded
• Allowed the light to be focused in a
particular direction
• Reduced absorption of the lens itself
• Lens = wasn't as thick
• PRISM

21. H O W D O Y O U
D I R E C T T H E L I G H T
O U T T O S E A ?
• Further Developments?
• PRISM
• Create extra prisms which are added to
the top and bottom of the lens
• Result = catch and redirect more light

22. F R E S N E L
L E N S
Come in all shapes and sizes

23. H O W D O Y O U
D I R E C T T H E
L I G H T O U T T O
S E A ?
Revolutionised Lighthouses and
made them better at their job!
Lighthouses could now redirect
more light and they could be
seen even further distance's
away.

24. L I G H T H O U S E S
M A I N
F U N C T I O N ?
Signaling

25. L I G H T H O U S E S
M A I N U S E ?
• Depends on the geography surrounding it

26. L I G H T H O U S E S M A I N
U S E ?
• Depends on the geography surrounding it:
• Dangerous rocks and shorelines
• Safe Harbours
• (Vessels can move from a better position with
this knowledge)

27. W H AT K I N D O F
L I G H T H O U S E I S
O N S H O R E ?
• Lighthouse
• &
• Light Station
• (base of operations mariners can use)

28. W H AT K I N D O F
L I G H T H O U S E I S
O N S H O R E ?
• Light Characteristic will indicate that
• L.C. = Flashing

29. W H AT K I N D O F
L I G H T H O U S E I S
O N S H O R E ?
• Light Characteristic:
• Lighthouses can use a series of flashes
and sometimes different colours to
identify themselves to mariners.
• Flashing Code to mariners at sea.
• Flashing Light = light is bright for a
short time
• Occult Light = light is dark for a short
time

30. W H AT K I N D O F
L I G H T H O U S E I S
O N S H O R E ?
• Light Characteristic:
• Uses a different combination of light
types with different timings and
different colours
• Infinite numbers of L.C

31. L A N T E R N
R O O M
• Place where flashes of light are generated

32. L A N T E R N
R O O M
Some Lighthouses have rotating lens
made up of several BULLSEYE Fresnel
lenses.

33. L A N T E R N
R O O M
As each lens rotates, the light is beamed
out from the bullseye in a single
direction.

34. L A N T E R N
R O O M
Ven though it looks like it is flashing, the light is ALWAYS
ON.
It's the rotation of the lens that gives the flashing effect.
There are flashing light's also too, depending on the
lighthouse.

35. L A N T E R N
R O O M
FLASHING FILTERS:
Same lighthouses have coloured filters,
indicating dangerous rocks or to communicate
with mariners of potential dangers ahead.
Same for the colours of different lighthouses and
their stripes. = DAYMARKS

36. A I D S T O
N AV I G AT I O N
• Lighthouses
• Life Buoys
• Light Stations
• Beacons
• Section Lights
• Coast Guard Personnel
• Lightships

37. L I G H T H O U S E S
Thanks!

38. - Y O U T U B E
H T T P S : / / Y O U T U . B E / 0 7 2 W P V M 7 A S 8 ? F E A T U R E = S H A R E D
- G O O G L E
- C H E C K O U T:
G R A C E O ' M A L L E Y
References