Observations on some Experiments in Electricity. 57 
form have caused them to be mistaken for ancient tombs, by suppo- 
sing that they were formerly the center of a vortex of water? 
It may be inferred from the preceding experiments and observa- 
tions, that the cause of water spouts is purely mechanical, and that the 
movement of the air alone, is sufficient to produce them; but in dis- 
carding electricity, as the immediate cause of the phenomenon, it does 
not follow that it may not be a remote cause, since it is possible that 
this agent assists much in the formation of whirlwinds and of winds 
which produce them. 
Art. VI.—Observations on some Experiments in Electricity; by 
Watrer R. Jounson, Professor of Mechanics and Natural Phi- 
— in the Franklin Institute, Philadelphia. 
1. The electric spark. 
The appearance of the electrical spark, passing through air, has 
been observed with considerable attention by philosophers, and the 
various phenomena of its luminous track marked, with a reference 
to certain theories eee the nature of the principle by which 
they are occasioned. ush and the star, were formerly con- 
sidered almost aes in favor of Franklin’s hypothesis. The 
experiment of Cavallo and Singer, in which a pith ball laid in a non- 
conducting groove, is propelled towards the negative point of the 
discharger, has also been cited in favor of the same theory, as well 
as the direction of the flame of a taper placed between two balls 
oppositely charged, and that of the revolution of a light float wheel, 
‘acted upon by the electrical current. But since it has been discov- 
ered that some bodies have different conducting powers in reference 
to the two opposite electricities, or “ decivinal states,” it has been 
doubted whether the above cited experiments afford any decisive in- 
dications in regard to the point in question 
There is, however, one interesting phenomenon which is not recol- 
lected to have been fully described by any writer on the subject.* It 
ee) pont, t, has been taken by Berzelius, and a more distinct statement 
res ate it is ae homson in his treatise on heat and electrici rs The former in rd 
spect gt his C ry; ee edit. p. 106,) maintains that “the spark is not a mere transmissio 
of the chouiaioley “3 3 ‘= elect pay body, toa pipiens hich itapproaches. It is composed of the 
ositi tte pie tri of bagi é bodies, and the negative electrici ni fo of the nl which unite and 
toot ppb ian is nthe space which the spar Ss to traverse. ody 
which coeeehes the. conductor, be neat th rounded, tho sdet rappears in the middle of the 
‘space between the two bodies. At this — . { union, the spark snaps and all the elec- 
al nome’ i a e spar) non 
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of the neutral point,) I have seldom found an bag ewes beg was willing to believe in the exist. 
ence of the x int until I had shown him the experimen 
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