118

Stone Henge June 19th 1877

[William E. Darwin]

[in margin by Darwin:] Previous part about the Ring

3 We took the following measurements at two rings near Stone Henge thus.

The rings consisted of a small mound & ditch thus, and were about 50 yards in diameter from bottom of ditch to bottom of ditch.

[sketch] see larger diagram Point where depth of mould was found. Inside of ring

The depth of mould was found by thrashing a small spade into the ground until it was stopped by stones, and the measuring from the top of the blade of spade

Depth of blade of spade = 5 3/4" Width of blade = 3 3/8",

These measurements were made 5 yrds apart, and the bearing of the centre of the ring from every other of these points was taken with prismatic compass.

118v

[sketch and calculations]

119

4.

Stone Henge South Ring

Bearing of centre of ring from mount by prismatic compass

depth of spade = 5 3/4= 23 (1/4")

1. Depth as measure from top of the NW spade in inches

2. Do. in quarter inches

3. Thickness of mould in quarter inches

[annotation by Darwin:] (very average thickness is well over 1 3/4)

See larger curve

120

5)

Stone Henge North Ring

Bearing of centre of Ring from points of observation

Thickness of mould [annotation by Darwin:] is 1/4 inches near base of ditch — one inner side

[Table of measurements]

See larger curve

*Results doubtful from rabbit holes.

121

6)

South Ring

At about the points marked SW and N.E on the curve the following measurements were taken close together

[annotation by Darwin:] Does this relate to bottom of ditch? Where

S.W. Depth of mold

2 1/4

2 1/2

2 1/4

2 1/4

2 1/4

2 1/4

13 3/4 = 13.75 [÷] 6 [=] 2.29

Average 2.29

See curve *

NE. Depth of mold

1 1/4

1 1/2

1 1/4

1 1/2

1 1/4

2

8 3/4 = 8.75 [÷] 6 [=] 1.458

Average 1.458

See curve *

This side was far more stoney on the surface of the grass

About 60 yds

122

[graph] depth of mould

The [alescissa] represents the bearings of the centre from points of observation

123

[diagram] bottom of slop half way down half way down slope Top Depth of mold. Top Half way down slop Bottom of slope

P.P. points of observation

[by Darwin:] The mean of the measurements at each point

Rough outline of mound.

North Ring

123b

North Ring

[graph:] P. P. points of observation; Diagram: Rough outline of mound

124

7)

Deviation of compas

∠0 = circular measure 2.9/10

I found that prismatic compas gave the bearing of a road at Southern plain to be 306º; and by the map that this road made an angle whose circular measure was .29 north of west that is an angle of 17º

Or, 306º of prismatic compas corresponds to 270º + 17º = 287º

306 [-] 287 [=] 19

∴ to get true bearing subtract 19º from reading of compas.

125

8

The following measurements were taken with spade as before at North Ring

[sketch]

This sketch shows the position that the measurements were taken, 3 measurements were taken at each point near together.

[sketch]

[annotation by Darwin:] (Earth ought to be thicker in bottom of ditch than elsewhere.)

If wind has influence, mould at A ought o be thicker than at B — & slight at D than at E

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9)

North Ring

N. E side of Ring roughly

Depth from top of spade	Thickness of mould	Mean	N. E Thickness of mould	S W Thickness of mould
Top 4 1/4 4 3/4 4 3/4	1 1/2 1 1	3.5/3 = 1.166	Top of Bank	Top 1.75
1/2 way down 4 3 1/4 4 3/4	1 3/4 2 1/2 1	5.25/3 = 1.75	Halfway from Bank	3.25
Bottom 2 1/4 1 3/4	3 1/2 4	7.5/2 = 3.75	Bottom of Bank 3.75	3.66
10 yrds from Top 2 1/4 2 3/4 2 1/2	3 1/2 3 3 1/4	9.75/3 = 3.25	On plain 10 yard	3.5

See smaller curve

3.25 [+] 3.5 [=] 6.75 [÷] 2 [=] 3.37 thickness [illeg] , mould on plain 10 yards outside ditch of northern Ring

127

10)

North Ring

SW side of ring

	Depth of mould	Mean depth of mould
Top 4 3 3/4 4 1/4	1 3/4 2 1 1/2	5.25/3 = 1.75
1/2 way down 2 1/4 2 3/4 2 1/2	3 1/2 3 3 1/4	9.75/3 = 3.25
Bottom 2 1/4 1 1/2 2 1/2	3 1/2 4 1/4 3 1/4	11/3 = 3.66
10 yrds from top 2 1/4 2 1/4 2 1/4	3 1/2 3 1/2 3 1/2	3.5

See smaller curve