Pellet Tests 146 Pendulum Experiments 36 Persistency Curves 119 Primary Colours 25 Primary Pigment Colours 27 Progressive Atrophy of the Optic Nerve 153 Purkinje’s Figures 7 Purples 24 Red and Green matched 72 Red-Blind Person’s Description of the Spectrum, A 63 Retina, Structure of 6 Retinal Fatigue 6, 30 Rods and Cones 8 Seat of Visual Sensation 7 Sensation Curves in Terms of Luminosity 93 Sensitiveness of the Eye 121 Simple Colours 17 Simulation of Red and Green Blindness 175 Spectrum described by the Tobacco Blind, The 143 Spectrum Test for Colour Blindness 181 Table of Wave-Lengths 17 Tables 211 Tobacco Ambyopia 140 Tobacco Blindness, Examples of 148 Violet Blindness 73 Visibility of an Object in light of different Colours 123 Visual Purple 9 White Monochromatic Vision 158 Wool Test, The 170 Yellow Spot 4 Yellow Spot and Colour Mixtures, The 28 Young’s Theory, Modification of 196 WORKS ON PHOTOGRAPHY BY CAPT. W. DE W. ABNEY, C.B., D.C.L., F.R.S., _Late Royal Engineers_. INSTRUCTION IN PHOTOGRAPHY. Post 8vo., 3_s._ 6_d._ PHOTOGRAPHY WITH EMULSIONS. Post 8vo., 3_s._ NEGATIVE MAKING. Post 8vo., 1_s._ ART AND PRACTICE OF SILVER PRINTING. Written in conjunction with Mr. H. P. ROBINSON. Post 8vo., 2_s._ 6_d._ PLATINOTYPE. Written in conjunction with LYONEL CLARKE. Post 8vo., 2_s._ 6_d._ LONDON: SAMPSON LOW, MARSTON & COMPANY, LIMITED, ST. DUNSTAN’S HOUSE, FETTER LANE, FLEET STREET, E.C.