Introduction
This cache is a letterbox hybrid cache which will take in just a small number of the blue plaques which can be seen in the City of Leeds. These plaques offer an interesting insight into the building, people and institutions of the city, some lost, some still present to this day. This cache also makes a nod to the origins of letterboxing, where measuring distances and bearings were the most accurate method available to navigate from one location to the next. Most GPS units and apps available for smartphones these days are capable of projecting a waypoint using distance and bearings, so hopefully the map and compass can stay at home on this occasion.
The Task
At each location a blue plaque can be found (except at the posted coordinates where the plaque is green). In each case, the plaque is large, round, constructed of cast iron with a uniform coloured background and raised letters painted in white. All plaques are clearly visible from a distance and from a footway, there is no need to be standing in the middle of roads or the like to find them. All of the plaques have a number of digits on them. At each location, all digits should be written down and the first digit assigned the letter A, the second B, right up to the point that no more digits remain. The numbers from the current stage will not be needed at any later stage, so “A” at each of the 10 stages could be a different digit. At each location I will specify the range of letters which need to be used, which will help to confirm you are looking at the right plaque. These letters should then be substituted into the formulas for the number of meters (apologies to those who work in imperial) and the bearing to the next location. In each case both the distance and the bearing are expressed as 3 digit numbers, so potentially all 3 digits could equal 0 at some point during the task. I have tried to keep the maths simple where I can (i.e. by not mixing additions and subtractions). The information gathered at the first plaque will reveal the location of the second and so on and so forth until the 10th plaque will reveal the location of the cache container.
At each location I would recommend taking your next bearing from standing on the footway as close to the blue plaque as is reasonable rather than from the result of your previous bearing. Navigating on a bearing is not quite as accurate as navigating to a coordinate, so any minor errors could be compounded as you complete this task.
Times and Distances
I would expect this cache to take just over an hour to complete, however this may fluctuate massively depending on how distracted you may become by whatever else could be done in the city or whatever other caches you may be hoping to find en-route. All plaques can be navigated to along and viewed from a footway. In most cases the most efficient route should be obvious. There are many busy roads which may need to be crossed whilst completing this task, so be sure to make use of proper crossing places where they are available. The total distance covered along the trail will be over 2km with around half of this distance being covered between the 9th plaque and the cache. The final location is over 1km from the starting location so if you need to be back at the start location for a certain time (to for instance catch a train), don’t forget to factor in the (fairly direct) return walk.
The Plaques
Green Plaque 1 (letters A-Z):
(B)(F)(M+N+O)m (M+N+O)(M+N+O)(Z)°
Blue Plaque 2 (letters A-H):
(H)(C-A)(A+E)m (D-C)(F-C)(G-C)°
Blue Plaque 3 (letters A-L):
(A)(G)(D)m (E+I+L)(C)(J-K)°
Blue Plaque 4 (letters A-H):
(A)(D+G)(C)m (A-E)(H)(G)°
Blue Plaque 5 (letters A-J):
(J)(C-F-G)(D)m (J)(F+G)(A+G)°
Blue Plaque 6 (letters A-T):
(R)(O+P)(B)m (I)(A+L+M)(D+E+Q+T)°
Blue Plaque 7 (letters A-F):
(A)(A+B)(F-D)m (E)(B-F)(D-A)°
Blue Plaque 8 (letters A-H):
(A)(H)(B-A-E-G)m (E+G)(A+E+G)(F+G)°
Blue Plaque 9 (letters A-L):
(H-I)(H-E)(D)m (J-D)(L-D)(A)°
Blue Plaque 10 (letters A-H):
(C)(B)(A)m (A+E)(F)(G-E)°
The Cache
The hint for the cache should obviously and exclusively identify one location. The cache is a good sized plastic container inside a camouflaged bag which contains an ink pad, a stamp which is relevant to me (which must remain in the container), a log book and a pencil. There is no need to enter any dangerous areas to retrieve the cache. Happy hunting, and I look forward to reading your logs.