The monument was constructed of rag stone, it has been repaired numerous times, the latter being after it suffered from a lightning strike. This lead to a repair project some 30 years later, funded mostly by the Lottery with the remaining donated by local craft fayre monies.
It has recently been given the go ahead for continued works by local steeple jacks to make further repairs to the failing stones
The monument was erected one year after Sir William Cosway was fatally injured in a horse drawn cart accident.
Kentish Ragstone.
Rag-stone is a dull grey stone, which is still quarried near Maidstone in Barming. It has been used as road stones and cobbles and wall blocks. Although difficult to ‘dress’ with a regular face, it has been used as square and rectangular blocks for construction of buildings.
Kentish ragstone is a limestone drawn from the Hythe Beds of the Lower Grensand. It has been quarried for centuries. There is currently a quarry in Barming, which is due to expand its operation which was confirmed in 2011 after an appeal to the Secretary of State. And a second quarry at Blaise Farm. Ragstone is now used for many different building requirements, from being used in ready mix concrete, road building, and large blocks are used for sea defences.
Another use for ragstone was to make cannon-balls. And in 1419 King Henry V ordered 7000 of these from Maidstone quarries. Most of Kent’s medieval parish churches were built of ragstone and although in Tudor times stone buildings went out of fashion in favour of brick.
Ragstone occurs in a geological formation known in the Hythe Beds of the Lower Greensand, a layer of limestones running from Kent into Surrey which was laid down in the Cretaceous period.
Ragstone occurs in bands between 15 cm and 60 cm thick, alternating with bands of a loose material called Hassock. These bands are of similar thickness and the difference in colour between them gives quarry faces a striped appearance.
We are now going to explore the Curvature of the Earth. Historically the distance of the visible horizon at sea has been extremely important as it was the maximum range of communication.
An unforeseen benefit of the monument was its use as a navigational landmark for shipping. This actually also put it in jeopardy, as during the Second World War, the monument was threatened by removal.
On a clear day you can see the coastline from here...
You will need to work in either metres and kilometres, or feet and miles. Or you could do both if you wish.
Curvature of the Earth
The curvature of the Earth determines how far an item can theorhetically be seen. We are going to omit factors that effect the actual true horizon like weather and obstructions. The Earth is roughly a sphere, and it is possible to theorhetically see an item which is high enough from a maximum half of the globe.
We are going to use basic calculations, for an estimate to the distance. There are many slight variations in these calculations online. This is for an approximate geometrical estimate only.
For metres and kilometres, where the Earth is 6371km radius
where d is km, and h is the height above ground or sea level in metres.
For feet and miles
where d is miles and h is height in feet.
And as this is also related to the sea, you may be interested to work out this in nautical miles,
where d is nautical miles and h is height in feet.
For this EarthCache you should do the following as a guide to the Qs...
A. Observe the monument and the construction materials.
B. Find out your elevation from sea level. You can use your own device or what you find at the coords.
C. Find out the height of the monument. This can be found at the above coords. You will need to work in the same units of measurement as you did for B
D. Add the two units to give you a value for your h
E. Work out the distance that the monument can be seen from one, two or all three of the above equations.
Please submit the following answers to log the EC by clicking the "Message the owner" link at the top of this EC page.
1. Give a brief description of the ragstone, and do you think the repairs were also done with ragstone? Why?
2. What is the total height of the monument with the ground height above sea level?
2b. For an optional Q, why do you think the height of the monument was specifically the height in FEET that it is?
3. How far away can the monument be seen, using one two or all three of the calculations above?
4. On the plaque are some Towns and Cities with their distances, can the monument be seen from any of these places? Which ones?
4b. You may like to play with calculations, for your own amusement and explore more heights to see how high the monument would need to be to be visible in Calais (43 miles / 69km)
5. Why do you think that if you double the height calculated, the distance of sight does not double? Is there any shape you think the world could be for the height and sight to increase at the same ratio?
6. Email me the answers you have found for Q1-4 and your thoughts on Q5, and then please log your visit.
I hope you enjoy your visit and the fantastic views, (if weather allows!)