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150: Roundel

A cache by Jekub (adopted by MikeRobinson) Send Message to Owner Message this owner
Hidden : 10/04/2013
4 out of 5
1.5 out of 5

Size: Size:   micro (micro)

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Geocache Description:

A Jekub Puzzle Cache to commemorate 150 Years of the Tube.
Needless to say, this cache is not at the published location.

The roundel is a globally recognised symbol for the London Underground, it has previously been known as the Bullseye, and the Bar and Circle.

Transport for London continue to use the roundel as the identification of both TfL and its services.

The Roundel consists of an annulus centrally bisected by a horizontal bar which protrudes an equal distance from each side.


Calculate to 3 decimal places

Midway between Points F and A, Point J is the centre point of the annulus and the horizontal bar

The radius of the inner circle = line BJ
The radius of the outer circle = line HJ
The length of the bar = 2 x line FD
The height of the bar = line FA

Calculate XXXXX = Area of one face of the Roundel
The Westing = W000° XX.XXX (use the integer value of X)

Depth of Roundel = Y where:
if the integer value of X is even: then Y= 7.1186
if the integer value of X is odd: then Y= 7.117

NB: This will hopefully catch any rounding differences,
I have tried manual calculation and Excel with precision to 3DP.

Calculate ZZZZZ = Volume of Roundel (X x Y)

The Northing = N51° ZZ.ZZZ (use the integer value of Z)

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Decryption Key


(letter above equals below, and vice versa)

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