This information is now part of the larger site dedicated to PHAROLOGY: www.pharology.eu
This is intended to be a detailed description of how lighthouses work. We hope you find these sections useful. We begin with a series of questions answered about Light: The level of difficulty here varies. Some of the material is suitable for junior school students. Other pieces are rather more technical. We leave it to tutors to judge the suitability for their students.
1. What is light?
2. Where does light come from?
3. What is brightness?
4. How is light and brightness measured?
5. How far away can I stand and still see the light?
6. How do we talk about the light used in lighthouses?
7. Why not go on using brighter and brighter lights?
8. How do we know what luminous intensity to use for lighthouses?
9. Photometric and optical
units and definitions
10 The interaction of light
and materials
11. Reflection
12. Refraction
Next a short set of texts about sources of light
1. Light Sources
2. Coal
3. Wood
4. Candles
5. Vapourised Paraffin
6. Acetylene
The most important light sources are obtained from electricity so the next topics are about this.
1. Carbon Arc
2. Incandescent Light Bulb
3. Are there any other types
of bulb?
4. Where does electricity in
lighthouses come from?
We now have some pieces to explain the principles in navigation.
1. Sea charts
2. Latitude and longitude
3. Navigating with latitude
and longitude
4. Lists of lights
5. Leading Lights
6. The Origin of Navigational Aids
The next set of topics discusses the functions of lighthouses, in particular, the way the lights work.
1. How can you identify lighthouses from the lights they show?
2. The lighthouse optic
3. Aren't these optics of
different sizes?
4. But
lighthouses flash, don't they? Why is that?
5. Tell me more about
characteristics
6. Reflecting (catoptric) systems
7. Occulting lights
8. How exactly are the optics
rotated?
9. How is light of a
different colour used?
10. How is magnification used
in lighthouses?
11. How do lenses and prisms
work?
12. How do you collect even
more light?
13. What are the names for all
these bits and pieces?
14. Where do you find the
brightest lights?
15. Is there a method of
classifying the different sizes?
16. How do you go about
designing these systems?
17. Where does the power come
from in a lighthouse?
18. The horizon and the
height of a light.
19. Pragmatism in light
intensities