Other works referred to include--Construction des Usines au Point de Vue de l’Hygiène, by Ingénieur-Architecte Maniguet. Ch. Béranger, Paris, 1906; Hygiène Industrielle, by MM. Leclerc de Pulligny, Boulin, and others. J. B. Baillière et Fils, Paris, 1908; and many excellently illustrated trade catalogues issued by ventilating engineering firms, such as the Sturtevant Engineering Company, Ltd., London; Henry Simon, Ltd., Manchester; Davidson and Company, Ltd., Belfast; John Gibbs and Son, Liverpool. CHAPTER XIII PREVENTIVE MEASURES AGAINST LEAD POISONING--_Continued_ =Periodical Examination.=--In various codes of regulations a surgeon is required to make periodical medical examination of the workers. The term “surgeon” is defined as the “Certifying Factory Surgeon of the district, or a duly qualified medical practitioner, appointed by written certificate of the Chief Inspector of Factories, which appointment shall be subject to such conditions as may be specified in that certificate.” The wording of the regulation varies somewhat in different codes, but the intention in all is the same, and the following example from the Tinning Regulations will indicate the purpose and scope: “Every person employed in tinning shall be examined by the surgeon once in every three months (or at such shorter or longer intervals as may be prescribed in writing by the Chief Inspector of Factories), on a day of which due notice shall be given to all concerned. The surgeon shall have the power of suspension as regards all persons employed in tinning, and no such person after suspension shall be employed in tinning without written sanction from the surgeon entered in the health register. “Every person employed in tinning shall present himself at the appointed time for examination by the surgeon. No person employed in tinning shall, after suspension, work at tinning without written sanction from the surgeon entered in the health register.” Under the Special Rules for white-lead works, examination is required at weekly intervals; under the Special Rules for Earthenware and China, Manufacture of Litho-Transfers and Red Lead, and under the Regulations for Electric Accumulators, and Paints and Colours, monthly; under the Regulations for Tinning, Yarn dyed with Chromate of Lead, and Enamelling, at quarterly intervals, subject to the limitation or extension specified in the regulation quoted.