next message in archive
next message in thread
previous message in archive
Index of Subjects
Sent by accident to DW hence forwarded. ----- Original Message ----- From: "David & Alison Webster" <dwebster@glinx.com> To: "David and Alison Webster" <dwebster@glinx.com> Sent: Saturday, August 23, 2014 4:31 PM Subject: 60 post Neolithic ring; very long > ----- Original Message ----- > From: "Stephen Shaw" <srshaw@Dal.Ca> > To: <naturens@chebucto.ns.ca> > Sent: Monday, August 18, 2014 2:25 AM > Subject: RE: [NatureNS] Neolithic stone rings etd. > > But subunits of 60 segments are not part of this series, so that remains > rawhide-unexplained too. >> Steve (Hfx) > > Hi Steve & All, Aug 23, 2014 > Before launching into the 60 post circle I wish to make clear that I am > in no position to say that these circles were installed as observatories > nor divine how they located the positions for these posts. > > But I think it is fair to say that such circles could have been used to > record the apparent motion of the sun back and forth along the horizon in > the course of the year and if they were astute enough to build this circle > around a NS baseline then their records would be symmetrical, easier > therefore to grasp and less vulnerable to recording errors (West & East > readings should agree within measurement error). > In addition, if your survival depends upon crops grown then a calendar > (or some persons dedicated to keeping track of the seasons) is vital. And > in case those persons forget to carve a notch for a given day or two then > the observatory plus records would jog their memory. In a crude way such > circles could also be used to tell time with reference to sunrise (after > sunrise) or sunset (before sunset). > But most of all, there was not much leisure time back then so why would > they have put so much time and effort into building these rings if they > were of no practical use ? If not for analog calendar and perhaps trying > to understand the pattern or sun movement (& perhaps moon movement) then > why do it ? > > Getting back to the 60 post circle one would as before lay out a NS > baseline and then, taking a new tack, install two posts at right angles to > this baseline. Each of these quarters would eventually have 15 spaces > between posts on the circumference. The distance between all four posts > (N-E-S-W-N) should be equal and the astute ring designer would check these > distances and make necessary adjustments before proceeding. > > The number 15 can not be divided by halving so, assuming that formal > math was unknown, other ways must be used that require only a crude > counting system and a bit of logic from first principles. I soon realized > that a stone age method to divide a hypothetical 6' diameter marble disk > into 360 degrees would be impractical for dividing a large ring into 60 > parts so took a different tack. This became too involved to follow without > a figure so I filed an image on Flickr at--- > https://www.flickr.com/photos/91817127@N08/15011112022/in/photostream/ > > First of all what is being divided ? Initially only the arc of the > radius running between two of the posts (e.g. North and East) is known so > that is the problem: how to divide this arc of unknown length into 15 > equal lengths. And to do this readily one must derive a unit of measure > that is equal to unit edge of a 60 sided regular polygon that just fits > within the circle (these terms are for communication by e-mail not for > doing the practical job). > > Materials for measuring the arc between two corner posts e.g. North and > East: > 1) Four boat shaped measuring sticks about a foot long with a pointed prow > and a notched stern to receive the point of boat behind it; call these > boatlets. The working length (prow tip to notch point) should be the same > for all four. > 2) The radius strand that was used to locate the North & South posts. > 3) A leather shoulder bag with pebbles for use as counting and recording > aids (pacing along the arc would indicate roughly the number required). > and an empty basket to record each time a boatlet is placed along the arc > by moving a pebble from the bag to the basket. > 4) a wedge shaped slab of wood or rock coming to a point at one end and > not less than a boatlet wide at the other end. > 5) Four staff: > one to walk from the East post to the North post, just ahead of the > other three, with the radius strand pulled tight, > one to place boatlets along the arc defined by the radius strand > (stern notch to prow), > one to move a pebble from the bag to the basket whenever a boatlet is > placed and > one to hold the string of three or four boatlets and pass the rear > one forward to the placer. > > Unless by some fluke the arc length were exactly equal to some whole > number of boatlets there will be gap between the prow of the last boatlet > and the near side of the North post. Insert the wedge into this gap so one > edge touches the prow and the other touches the post and mark these two > points on the wedge so this length can be measured. On a scrap of flat > stone record the approximate radius of the North and East posts (This is > needed because the arc has been measured between proximal sides of the > posts.) > > Now the full length of the arc is known as the recorded number of > boatlets (the number of pebbles in the basket) + the wedge line + the two > post radii. The next task is division of this total length into 15 equal > parts. > > Materials for division of arc: > 1) a straight edge about 5' long. > 2) a flat rock about 14" x 14" squared on one corner for drawing right > angles. > 3) a flat slab of rock not less than 3 boatlets long and one boatlet wide > on one end or both ends. > 4) a scrap of hard rock (flint or quartzite) that is flat near a sharp tip > for inscribing lines on #3. > 5) Fifteen isolated compartments (bowls, areas of hide segregated by flat > rocks, hollows in sandy soil etc.) into which pebbles from the basket can > be transferred after the full arc has been measured. > > Methods for division of arc: > Using the above straight edge, chose the longest side of large flat > slab (#3) that has a surface most free of humps and hollows, chose this to > be the lower edge of the slab and inscribe a straight line near this edge > (slab baseline). Using the square (#2), draw a line that is perpendicular > to the baseline, of length equal to or greater than a boatlet and near the > end of greatest slab width [for ease of description assume this to be near > the right end of the baseline]. Call this corner B and mark on the > perpendicular the exact working length of a boatlet measuring from corner > B to upper point A. > Take a linen thread that is slightly longer than the baseline and fold > it back on itself four times, mark this length (1/16 of the