120 Mr. C. Tomlinson on some Effects of Lightning. 



coals also were scattered. The theory of the return stroke 

 is that such effects as the above result from the discharges 

 of the remote clouds producing electrical disturbances in 

 distant bodies, even some miles from the spot over which the 

 thunder clouds appear. 



The case related by Mr. Brydone resembles in several par- 

 ticulars the recent case communicated to me by Mr. Dudgeon. 

 In the one the hair was singed on the legs, and under the 

 bellies of the horses ; in the other there were marks of singe- 

 ing in the regions of the kidneys of the sheep. In both 

 cases the animals were struck suddenly stone dead. Mr. 

 Brydone, who, as we have said, examined the spot soon after 

 the accident, says : — " Had there been any convulsive 

 struggle, the marks would have been visible in the dust of 

 the road where they fell." And, as a further analogy, " a 

 shepherd standing in an adjacent field stated, that he had his 

 eye on the waggon at the very instant of the explosion, and 

 saw a vortex of dust arise." In Mr. Douglas's narrative the 

 soil was hurled upwards so as to cover the leaves of the trees 

 to a considerable height. 



Arago is so sceptical as to the possibility of a lightning 

 discharge from the ground upwards (de has en limit) that he 

 is disposed to attribute the explosions above described, in- 

 cluding the turning up of the soil, and the barking of the 

 roots of the trees, to the conversion of the moisture of the soil 

 into high-pressure steam by the intense heat of the lightning ; 

 just as he accounts for a large tree being split up into 

 matches by the conversion of the sap into the same tremen- 

 dous elastic force. But in the case at Coldstream, Brydone 

 says nothing about rain, and the principal effects occurred in 

 a dusty road. He also describes a very curious case, which 

 supports the idea of a discharge from the ground upwards. 

 A woman who was cutting grass on the banks of the Tweed 

 was suddenly thrown down without any apparent cause. She 

 called her companions immediately to her aid, and told them 

 that she received a sudden and violent blow on the soles of 

 her feet, but whence it proceeded she could not tell. At 

 the moment this happened there was neither thunder nor 

 lightning. 



Arago admits that the facts as to ascending lightning are 

 against him, although they do not amount to demonstration. 

 He is also sceptical as to the phenomena of ball lightning 

 (eclairs en boule) or that which moves through the air at a 

 comparatively slow rate, appearing like a luminous ball or 

 a globe of fire. Arago terms this ball lightning a stumbling- 

 block (pierre d' achoppement) for meteorologists, due probably 



