This volume, "La Photographie Animée," by Eug. Trutat, Director of the Natural History Museum in Toulouse, is introduced by M. Marey, a renowned chronophotographer. The book provides a comprehensive review of the history and development of animated photography, tracing the evolution of apparatus from early devices like the phenakistiscope and zoetrope to more advanced systems used by Marey, Edison, and others. It includes detailed descriptions of French machines and explains the processes of exposure, development, and printing of positive film. However, the book's value is somewhat limited as it focuses primarily on French apparatus and does not cover successful machines from other countries. In the "Letters to the Editor" section, the editor notes that he is not responsible for opinions expressed by correspondents and does not return rejected manuscripts. The article on the interferometer discusses the author's experience with Michelson's instrument, addressing concerns about diffraction and the estimation of visibility in spectral lines. The "Theory of Functions" section addresses specific inaccuracies in a review of a book on analytic functions by Prof. Burnside. The authors defend their work, clarifying points about convergent series, infinite products, and the use of the term "infini." The article on the tetravalency of oxygen discusses the discovery of pure oxygen phosphide and suggests that oxygen can be represented as tetravalent in certain compounds, supporting the idea of alternating valency in non-metallic atoms. The final section on the progress of wireless telegraphy highlights Marconi's successful messages transmitted across the English Channel, emphasizing the simplicity and practicality of his system. Prof. Fleming's letter underscores the importance of Marconi's achievement and the potential future applications of wireless communication.This volume, "La Photographie Animée," by Eug. Trutat, Director of the Natural History Museum in Toulouse, is introduced by M. Marey, a renowned chronophotographer. The book provides a comprehensive review of the history and development of animated photography, tracing the evolution of apparatus from early devices like the phenakistiscope and zoetrope to more advanced systems used by Marey, Edison, and others. It includes detailed descriptions of French machines and explains the processes of exposure, development, and printing of positive film. However, the book's value is somewhat limited as it focuses primarily on French apparatus and does not cover successful machines from other countries. In the "Letters to the Editor" section, the editor notes that he is not responsible for opinions expressed by correspondents and does not return rejected manuscripts. The article on the interferometer discusses the author's experience with Michelson's instrument, addressing concerns about diffraction and the estimation of visibility in spectral lines. The "Theory of Functions" section addresses specific inaccuracies in a review of a book on analytic functions by Prof. Burnside. The authors defend their work, clarifying points about convergent series, infinite products, and the use of the term "infini." The article on the tetravalency of oxygen discusses the discovery of pure oxygen phosphide and suggests that oxygen can be represented as tetravalent in certain compounds, supporting the idea of alternating valency in non-metallic atoms. The final section on the progress of wireless telegraphy highlights Marconi's successful messages transmitted across the English Channel, emphasizing the simplicity and practicality of his system. Prof. Fleming's letter underscores the importance of Marconi's achievement and the potential future applications of wireless communication.