GIBB — A CHAPTEU ON FOSSIL LIOIITNINQ. HQS 
several distinct currents, which would enter the surface at the 
distance of many yards from each other. 
The greatest depth to which the electric fluid has penetrated verti- 
cally, as demonstrated at Drigg, is forty feet ; but I should be 
disposed to estimate the length of horizontal fusion at a much greater 
amount. 
The majority of the fulgurites which I have had the opportunity of 
examining, have entered the sand vertically ; but some, again, ran 
along the surface of the sand iu a horizontal direction. And it is 
this latter form only that we can expect to meet with in a fossil state. 
As examples of horizontal recent tubes, I may refer to specimens from 
Dresden, in the British Museum and in the Museum of the Geological 
Society. In the former collection the tube is very small, and runs in 
a somewhat tortuous manner, giving off a small branch five inches 
long, the entire length being sixteen feet and two-thirds ; but the 
original must have been very much longer, as this is but a portion of 
it. This example was presented by Dr. Fiedler, who has published 
a work on fulgurites in German, to which I have not had access ; 
but was obtained " on the confines of Holland, in a sandy country ; a 
shepherd, after having seen the lightning strike a hillock of sand, 
found, iu the very point where it struck, a fulgurite." The Geological 
Society's specimen is eighteen inches long, and as large as a lead- 
pencil. Both of these examples are solid, without any internal cavity, 
and it seems a question in my mind whether actual tubes are ever 
found in any other than a vertical position. The examples in a fossil 
state which have come across my notice, and which first di-ew my 
attention to the subject, appear to have been fouud only in the solid 
form,* and partaking of the horizontal position. There are three 
flagstones on the eastern side of Tottenham Court Road which con- 
tain fulgurites of a lightish colour, running in forked directions. 
There is one on the eastern side of Russell Square, close to Guildford 
Street, on the surface of which a dark ferruginous tube of •' fossil 
lightning " runs diagonally across the stone, its diameter being about 
two lines. I have noticed them in thi-oe or four other places in the 
* I state this with some reservation, because I have seen a section of wliat looks 
like a lightning-tube in a sandstone door-step. It has four irregiilarly compressed 
sides, and presents very mucli tlie appeanuice of one of these bodies/ 
