2.15 P.M. 3.15 P.M. 



No. 9. Variation in potential due to steam from passing trains. 



W^%#»jiw 



No. 10. Variation in positive potential due to "shunting" of trains. 



No. 11. Taken simultaneously with No. 10, but at a distance of more than a mile from 



the railway. 



