Test No. 105 - "Comparison of Readings of Self-Potential at Constant Temperature"
(R-25 and EL-11)

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June 18 - 28, 1977
Stewart Ct. Laboratory
Sunnyvale, CA

Copyrighted © by The Townsend Brown family. All rights reserved.


To compare the self-potential readings of Catalina granite R-25 (same as used in the UC Berkeley mineshaft) with the electrolytic capacitor EL-11.


As tested in the mineshaft at Berkeley, Rock R-25 (without polyurethane coating) was placed in a cast aluminum box with flanged lid secured in place by 6 screws. Although the lid fitted tightly there could have been air seepage concurrent with changes in barometric pressure. The question as to a possible contribution by the high humidity deep within the mineshaft and moisture upon the surface of the rock remained unanswered.

In preparation of the present test, the aluminum box containing rock R-25 was filled with new oil (Quaker State No. 10) so as to completely immerse the rock. The lid was hermetically sealed in place with GE silicone. This was to insure against any leakage of air into the box and any possible effect of changes due to humidity and barometric pressure. The box was placed within constant temperature chamber No. 1 and held at 100oF +/- .2oF.

Capacitor EL-11 was also placed in the constant temperature chamber alongside the metal box containing the rock. The capacitor (G.E. 90,000 ufd 10 V DC) is sealed during manufacture so that no effects of humidity or pressure are expected. Both the capacitor case and the cast aluminum box containing the rock were electrically grounded.

This series of observations continued for 10 days. Results are shown on the attached chart.


The attached charts show pronounced diurnal variations for both the rock and the capacitor. They appear essentially in phase. No "glitches" were observed with either sensor during the period of this test.


Catalina granite R-25, under carefully controlled conditions at Sunnyvale, showed virtually the same diurnal pattern as in the mineshaft at Berkeley.

A chart is attached comparing the results.

Graphic - Figure 1

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