On. the Galvanic Polarization of buried Metal Plates. 377 
_ A question of a more general kind, and embracing this last, ° 
would be the problem of dividing the whole of the same system 
of triads into 13 disynthemes, without annexing the further con- 
dition of monosynthematic divisibility. So there is the simpler 
question of constructing a single disyntheme to the base 15 
without any condition annexed as to its decomposability to 7 
synthemes. 
K, Woolwich Common, 
December 1860. 
LVII. On the Galvanic Polarization of buried Metal Plates. 
By Dr. Pu. Caru*. 
AST year, in consequence of the disturbances which were 
observed in the telegraphic wires during the appearance 
of the northern lights, Professor Lamont was induced to contrive 
an apparatus at the observatory of Munich in order to examine 
more closely into the occasional motion of the earth’s electricity, 
and to determine its magnitude and direction. For this purpose 
large zinc plates were buried on the north, south, east, and west 
sides of the observatory garden ; the north plate being connected 
with the south, and the east with the west, by means of copper 
wires, which were brought into the observatory and connected 
with galvanometers. As Professor Lamont, in testing this appa- 
ratus, remarked certain phenomena which he attributed to gal- 
vanic polarization, it appeared to me advisable to subject the 
matter to a more careful examination, and to obtain more accu- 
rate measurements. 
_ Through the wire that connects two of the above-mentioned 
zinc plates, a current, which I shall call the terrestrial current, 
is perpetually circulating, the intensity of which is indicated by 
a fixed deviation of the galvanometer. If a galvanic element be 
inserted in these conducting wires and again removed, then, pro- 
vided it has caused no modification in the conductor, the needle 
of the galvanometer will return to its former position. But if, 
on the other hand, a state of galvanic polarization has been pro- 
duced in the zinc plates, then the deviation of the needle of the 
galvanometer, after the removal of the element, will be greater 
or less than that exhibited by it originally, accordingly as the 
direction of the galvanic current has been opposite to, or the 
same as that of the terrestrial current. 
On trial, the latter result exhibited itself so unmistakeably that 
no further doubt could be entertained of the occurrence of galvanic 
polarization. In order to measure the magnitude of the effect 
produced, I made use of a weak Daniell’s cell, which I inserted 
* Translated by F, Guthrie from Poggendorft’s Annalen, No. 10, 1860, 
