Unpublished appendix, regarding 'An account of experiments made with the view of ascertaining the possibility of obtaining a spark before the current of the voltaic battery is completed' by J P [John Peter] Gassiot Gassiot outlines new research he has discovered on the topic of electricity by a Dr Henry. Annotations in pencil throughout. Subject: Physics / Electricity Written by Gassiot at Clapham Common [London]. 19 November 1839