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.

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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 306°; and by the map that this road made an angle whose circular measure was .29 north of west that is an angle of 17°

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

306 [-] 287 [=] 19

∴ to get true bearing subtract 19° 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