Page:Philosophical Transactions - Volume 054.pdf/280

 to run off in streams, a great portion of the electric matter runs off in, and is dissipated by, these streams; and buildings are thereby preserved from damage.

What happened to St. Bride's cannot but give us some apprehensions for that most noble edifice in its neighbourhood; I mean St. Paul's. This is above an hundred foot higher than St. Bride's, and therefore more in the way of accident from thunder storms. Upon its mangnificent lanthorn is placed a cross of metal, which is inserted into the stone of the lanthorn; and this is supported by a truncated cone of brickwork, which arises from the arches of stone below. The cupola is covered with lead, which is continued to the spouts of the same material. These bring down the water to the stone gallery under the cupola, and end within about a foot of the stone. From hence the water is conveyed a considerable distance, in a stone trough or channel, to the leaden spouts; and these are carried down the building, and terminate, as I was informed upon inquiry, in the common sewer. By this arrangement the metallic communication is interrupted. In thunder storms during rain, the water carries off in its streams the electricity, as perfectly, as the most compleat metallic communication would; but when there is no rain, it is otherwise; and these interruptions are the great cause of danger. To Iessen which, as far as we can conclude at present, it would be expedient to make, by the means of several copper wires, small rods, or pieces of lead, a metallic communication between the gilded cross, and the lead of the cupola: and again, from the leaden spouts of the stone