70 MB. WILLIAM STURGEON ON LIGHTNINO 



bronze, to be about 2 feet and a half diameter, which would 

 leave 7 feet for the height of the cross above the surface of 

 the cap. 



A more decisive indication of the precise spot where 

 the electric fluid first struck the cross, could not possibly 

 have been marked than by the well-defined boundary of 

 discoloration of the bronze. And, what was still more 

 satisfactory, the obliquity of the upper boundary line of 

 discoloration showed that the cloud from which the light- 

 ning proceeded was, at the time of the discharge, on the 

 north-west side of the church. For on that side of the 

 shank of the cross was the highest point of the margin of 

 discoloration, and on the opposite side was the lowest 

 point of that margin ; and the figure of this upper margin 

 or boundary line was that of an ellipse, embracing the 

 shank of the cross, and sloping downwards from the north- 

 west to the south-east side. 



The highest point of this margin was not quite a foot 

 and a half above the surface of the globular cap, leaving 

 more than 5 feet of the best conducting metal known, above 

 that point, untouched by the lightning. The gilt bronze, 

 from that boundary line down to the horizontal equator of 

 the globular cap, was converted into a leaden colour. At 

 the equator the discoloration became scattered and lost 

 in a multitude of ramifications on the lower hemisphere ; 

 these ramifications were, with the exception of colour, very 

 similar to those made on the surface of a glass jar by spon- 

 taneous discharges. Such were the external effects of the 

 lightning on this mass of hollow bronze metal, the conduc- 

 tion of which was assisted by an interior bar of copper, 

 which supported it on the apex of the spire of masonry. 

 The same copper bar reached downwards in the axis of the 

 spire nearly 40 feet, and rested on the intersection of two 

 horizontal bars of iron, placed at right angles to each other, 

 having their extremities fixed in the masonry. 



