Народ.Ру: 1.2.5.1.11. By William Thomson. On the Reduction of Observations of Underground Temperature; with Application to Professor Forbes''s Edinburgh Observations, and the continued Galton Hill Series. Phil. Mag. 1861, V.XXII. (pdf, англ.).

1.2.5.1.11. By William Thomson.
On the Reduction of Observations
of Underground Temperature;
with Application to Professor Forbes''s
Edinburgh Observations,
and the continued Galton Hill Series.
Phil. Mag. 1861, V.XXII.
(pdf, англ.).