Sunday 13th August 2017
|WHERE ? MAP HEIGHTS FIGURES TIMING TRACK EXTRA FINAL READ ME|
Our circular Essex walk, ably led by Paul took in the gently undulating countryside around Ingatestone. Paul reckoned it was about 9 miles in length, but we made some deviations and looked at some interesting churches. As a result, my GPS suggested a distance of about 10½ miles. I base what follows on the raw GPS readings, admitting up-front that I did not manage reprocess these GPS readings. Importantly, it was a comfortable, and "very doable" Sunday walk, at a steady pace, giving us time to look at "the sights" and enjoy tea at Ingatestone Hall. Walking and weather conditions were good. All excellent!
Now prepare ye for some plots and graphs. Not too overwhelming, but hopefully quite interesting! You will see here:
Our start and end points were both Ingatestone (INT) station, which lies within a radius of 25 miles, roughly east north east of the centre of London. The centre of London is officially taken as the intersection of The Strand, Whitehall and Cockspur Street. This intersection is often referred to as Charing Cross, not to be confused with the nearby Victorian Eleanor Cross itself, nor the station in front of which the cross stands. The detailed figures, for the fun of it, are as shown below.
Our "straight line" distances are actually "great circle" distances on the earth's surface. We assume the earth to be spherical, which is not far off the mark. Assuming the earth to be a sphere gives us an error of about 0.1% in our distance values. Not that much really! Can't complain! Indeed, we can speak of the distances as the "hypothetical crow" (cornix hypothetica) flies.
Our walk was circular, starting and finishing in Ingatestone. At about 10½ miles it was a relaxing Sunday walk with no really steep ascents. Being mid-August, we of course got back comfortably before nightfall, with time to spare for tea at Ingatestone Hall.
We were east of the Greenwich meridian. The map grid scales translate to about 1.112 Km per 0.01° latitude and a mean of 0.690 Km per 0.01° longitude (WGS standard), both when using 6371.0 Km as the volumetric mean radius of the earth. It is interesting to compare the present longitude distance-to-degree ratio with that for other walks. If you do this, you will see that the further north you go, the less Km per degree longitude you get. Once you get to the Lake District the reduction in this ratio compared to that for walks in the south-east is quite noticeable. In Scales, in the Lake District, we already have a slightly smaller value of 0.644 Km per 0.01° longitude - a difference of 54 metres per 0.01° longitude compared with our present Folkestone to Dover walk.
Because we don't live on a flat earth - unless you are a convinced "flat-earther" - maps are inevitably a distortion of what is. In other words, it's all a matter of mapping a curvaceous surface onto a flat surface. We don't want to carry curvaceous representations of the terrain on our walks, do we? In our case, the northern length of our map grid is stretched out by something like an extra 0.09 %, to make it the same on the page as the length of the southern part of our map grid. Not that much for hiking purposes really! Can't complain.
Our maximum and minimum heights were 105 and 38 metres respectively, with a total ascent of 116 metres - so not unduly taxing on the constitution, and certainly within the physical capabilities of most IVC members! Not only can you see this on the height profile below, but also in the "Facts and Figures" table in the next small section. Of course, it's our total ascent, and not the maximum height we reached, which is really an indication of our fitness.
Visual inspection of the height profile tells us that the gradients on our walk were really very modest and very doable!
Here are some "vital statistics" in metric and imperial units. The total length our walk is measured on the surface of the WSG84 spheroid. However, we can consider this, without undue loss of accuracy, as being on a conceptual "flat" plane at mean sea level, using the OS sea level reference as explained on OS "hiking" maps. There you are!
On any walk there are considerations which are very real but tantalizingly out of ready reach of those who wish to espouse a numerical approach to many of life's activities. Here are three considerations for starters.
It's one thing to discuss the terrain over which we walk. It's quite another to ask how we personally respond to walking over that terrain. There are a number of considerations, of which timing and speed can be taken as starting points, should you wish to wax enthusiastic in these areas!
If you are keen to see our walk superimposed on an Ordnance Survey® (OS) map or on another system such as Google Maps®, then you can use this file to do so. The data are based on WGS84. Of course, for copyright reasons, I do not show the OS-based or Google-based maps here.
Any map is an approximate representation of what is. Practicality and scale are relevant considerations. We are not dealing with a planning application calling for detailed spatial descriptions of intricate boundaries. For us in the hiking community, the degrees of accuracy and precision should be just enough to give us useable and helpful knowledge of the terrain about us and beneath our feet. I hope my humble endeavours on this page are in this respect interesting for, and useful to, you my reader!