[SYSTEM]
You are answering a single information-extraction question. Use ONLY the supplied source material. Do not use prior knowledge. Give a clear, concrete answer with the specific number, name, year, or value asked for.

[USER]
--- SOURCE ARTIFACT (M3-L4) ---
# Table 049 — TABLE II. TIDAL SCALES (Heights are given as feet above or below Chart datum)

PDF page: 200

```csv
Tidal level,Plymouth (ft.),Salcombe (ft.)
E.H.W.S.,Bg,B73
M.H.W.S.,15°7,16
M.H.W.N.,TEAS,I2°6
E.H.W.N.,10,10°3
M.T.L.,8-2,8-8
E.L.W.N.,57,6:6
M.L.W.N.,4:6,55
M.L.W.S.,0-2,I'l
E.L.W.S.,—1°6,—0°7
```

--- END ARTIFACT ---

Question:
A tidal observation table in Vol 27 lists water levels at Salcombe for Mean High Water Springs (M.H.W.S.) and Mean High Water Neaps (M.H.W.N.). No intermediate tidal state is listed between those two. Estimate the water level at the midpoint between M.H.W.S. and M.H.W.N. by linear interpolation between the two recorded values.

Answer concisely. Cite the row/cell/section you used. State your final numerical answer clearly.