- 
Feb. 15, 1883]. 
which tend to increase, and others to decrease the corrosion, In 
a solution of potassic cyanide pure silver is always protected by 
being made a cathode. The influence of variations of strength 
of acid was tried in several cases. 
The results, which at first were apparently contradictory, were 
found to depend upon a number of conditions, and it would 
require an extensive research to determine the limits of those 
conditions; and what the proportions are, in which all those 
separate influences participate in producing the effect. Unequal 
capillary action is one of them, and its effect is described in a 
separate paper entitled, “ The Electrolytic Balance of Chemical 
Corrosion.” Another is unequal corrodibility of the metal it- 
self. This was investigated, but how it arose was not clearly 
ascertained, ‘Traces of certain kinds of soluble impurity in the 
liquid was also a disturbing circumstance. The altered chemical 
composition of the liquid around the cathode, caused by sub- 
stances set free or formed by electrolysis, was another influence ; 
this was investigated in the case of a silver cathode in a solution 
of potassic cyanide, and the protective influence of the current 
upon the cathode was found to be partly due to the formation of 
potassic hydrate; the current, however, operates also ia some 
other manner. The effect of temperature was also examined, 
and it was found that the current exercised a greater protective 
power when the liquid was hot than when it was cold ; the cor- 
rosive effect without a current was also greatest (as might have 
been anticipated) in the hottest liquid. The effects were further 
influenced by the degree of strength of the current ; the greatest 
strength of current exercised the most protective power, and a 
large number of experiments were made expressly to test the 
question whether difference of electro-motive force alone, inde- 
pendently of difference of strength of current, affected the rate 
of corrosion, but the difficulty of insuring perfect uniformity in 
all the other conditions which affected the corrosion was so 
great that sufficiently decisive results were not obtained. 
THE MOVEMENTS OF AIR IN FISSURES 
AND THE BAROMETER 
FROM time to time attention has been called to the property 
exhibited by certain wells in different parts of this country 
of maintaining an active and permanent circulation of air. It 
was observed that currents alternately entered or issued from 
fissures in the sides of the wells, and though in some cases the 
first emission on sinking the well consisted of choke-damp, the 
gas subsequently passing consisted of no more than atmospheric 
air. While it was clear that the currents were not due to the 
evolution of any gas by chemical action in the rock or the water, 
an explanation of the phenomenon was found inthe fact that the 
changes in the direction of the circulation coincided precisely 
with the changes of movement of the barometer, the current 
being outwards with a falling glass, inwards when the barometer 
was rising, and ceasing altogether when no change in the atmo- 
spheric pressure was taking place. The strength of the currents 
moreover was found to be proportionate to the rapidity of the 
barometric movements. 
The name of Blowing Wells has come to be applied to such 
wells in consequence of these properties. From their extreme 
sensitiveness to changes in the atmo-pheric pressure, they have 
been found to give useful indications of the approach of bad 
weather. Their warnings are rendered audible by fixing horns 
or whistles in an air-tight covering, in such a way as to sound 
readily to the outward current, or to give a different note for 
an outward or inward movement of the air. 
The first blowing well of which we have an account appears 
to have been of an entirely artificial origin. A well was sunk 
at Whittingham, near Preston, to a depth of eighty feet, and 
being afterwards abandoned, was covered with a large flagstone 
pierced by a small hole. Currents of air were observed to enter 
or issue from this hole, according as the barometer was rising or 
faJling, and a tin horn fixed in it became auiible at a consider- 
able distance. Similar phenomena were exhibited by a cess- 
pool, intended to receive offensive residue from some chemicai 
works. The pool was arched over, a small hole being left for 
the passage of the refuse; a fall in the barometer was made 
unpleasantly evident by the issue of offensive vapours. 
Subsequently it was noticed that three wells in the New Red 
Sandstone, in the neighbourhood of Northallerton exhibited the 
same peculiarity. The wells ‘‘blow” through fissures in the 
sandstone just above the water-level. The changes in the 
* J. Rofe, F.G.S., Geological Magazine, vol. iv. p. 106, 1367. 
NATURE 
375 
direction of the currents coincide precisely with the movements 
of the barometer, and the outward current is made to blow a 
“buzzer,” which is said to be audible at a mile distance.! In 
the years 1879-80 a series of interesting experiments on one of 
these wells, situated near Solberge, three and a half miles south of 
Northallerton, was made by Mr. Thomas Fairley, F.R.S.E.? 
After stating that the water has a composition similar to that 
coming from chalk or limestone, and that, though on the first 
opening of the fissure a violent outburst of choke-damp had 
taken place, the gas subsequently issuing did not differ appre- 
ciably from common air, Mr. Fairley gives a detailed account of 
observations made on the volume of air passing. The currents 
passed through fissures in the sandstone at a depth of forty-five 
feet from the surface of the ground, and just above the level of 
the water. The measurements were made firstly by a vane- 
anemometer, and subsequently by two large dry meters, con- 
structed to pass 3,000 cubic feet per hour; these had been 
substituted for two of the largest meters in the possession of 
the Leeds Corporation, which had been thrown out of gear by 
their incapacity to pass the air fast enough. As a result of 
these experiments it was found that a fall of the barometer of 
0°26 inch was accompanied by an outflow of 83,900 cubic feet of 
air, and by an application of Boyle’s law it was calculated the 
total capacity of the fissures must amount to nearly 10,000,000 
cubic feet. 
The existence of currents obeying the same laws is equally 
obvious in a well at Langton at a few miles distance. The well 
has been long disused, and the water is exceedingly foul, not- 
withstanding which a candle burns clearly at the bottom. A 
third instance occurs at Ornhams near Boroughbridge, where the 
roar of the air-currents passing into the crevices of the rock has 
been compared by a workman to that of the waterin a mill-race. 
No observations, further than those necessary to prove the exist- 
ence of the currents, have yet been made on these wells. 
At Hopwas a well has been sunk for the supply of Tamworth 
to a depth of 168 feet, the water standing naturally a depth of 
129 feet. The shaft passes through alternations of shale and 
sandstone, one of the beds of the latter, met with at a depth of 
ninety-six feet eight inches, b2ing described as ‘‘ light fissured 
sandstone thirty feet four inches.” * From a fissure in this bed, 
at 115 feet from the surface, there issued a violent rush of 
atmospheric air, which soon spent itself, and was succeeded by 
currents showing variations coincident with the barometic 
changes. The currents have been noticed in one fissure only, 
an irregular opening, of two and a half inches in height by one 
inch in width, in a nearly close-sided vertical joint. Experi- 
ments on the amount of air traversing this fissure are now in 
progress. 
The same properties are exhibited in an equally well-marked 
degree in a well belonging to Mr. A. Potts at Hoole Hall, near 
Chester. The well is eighty-one feet deep and contains ten feet 
nine inches of water; it is sunk through glacial deposits, con- 
sisting of a tough clay overlying a sand of variable thickness, 
into the New Red Sandstone, but, being an old well and lined 
with brick to the water-level, the exact nature of the strata and 
the position of the fissures is unknown. Communicating with 
the interior of the well by pipes, are two whistles of a different 
tone, and a pressure gauge; the deeper-toned whistle sounds to 
an inward, the shriller-toned to an outward current, and were 
they allowed to act freely during unsettled weather, these 
whistles would render sleep in the adjoining house impossible. 
It is stated by Mr. Potts that changes in the atmospheric 
pressure are shown more rapidly by the pressure gauge of the 
well than by a mercurial barometer, and that whenever there is 
a sudden change for rain, the water in the well becomes agitated 
and slightly discoloured. An appearance of ebullition was 
noticed also in the Solberge well, but has been attributed by 
Mr. Cameron to the falling of fragments of mortar. The 
movements of the watet in the Hoole well are being made the 
subject of experiment by Mr. Potts. Similar, though less 
powerful, currents have been observed in two other wells within 
a distance of 500 yards of Hoole Hall. The wells are in a 
situation where a similar sequence of glacial deposits probably 
exists, but further particulars are at present wanting. 
The fissures from which the currents in biowing wells issue 
occur usually near, but just above, the water-level. Above 
them there is provided an air-tight covering in the glacial clays, 
T A. G. Cameron, Geological Magazine, vol. vii. p. 95, 1880. 
2 Proc. York Geol. and Polyt. Soc., N.S., vol. vil. p. 409, 1881. 
3 Mr. H. J. Marten, Eighth Report on the Circulation of Underground 
Waters to the British Association, 1882. 
