principle of, [98]

resistance of, [100]

efficiency of, [101], [102]

overrunning, [101]

Nicol prism, [53]

Paper for electrolytic receiver, [56]

Parabolic reflector, [8]

Period of galvanometer, [43], [44], [46]

Photographic Daily Companion, [105]

Photographic films, [40], [43], [45], [53], [54], [62], [85], [86], [98]