Folder 15 May - July 1875. Funck's project to substitute lens apparatus for reflectors on light ships by Henry, May 6; Report on investigation relative to the use of mineral oil for Light-House purpose by Henry, May 26; Comparative Table of Mineral Oils, May 28; Letter to Henry from the Manager of Elain Oil, May 31; Lighthouse apparatus diagrams, May; Extract from Light House Board Minutes, June 2; Lard Oil consumption per hour, June 2; Letter to Henry from J. C. Woodruff, June 4; Letter to Henry from R. Allen, June 25; Information sheet, July 5; "Meyer's Electrical Fog-Signal" by Henry, July 9; Letter to Henry from Orrin Dinsmore L.H., July 9; Lamp experiment data tables, July 29; Notes from Light-House Depot, Staten Island, New York July 31.