The professors engage to deliver, annually, not less than fifty lectures each, on natural philosophy and the mechanical arts; and on chemistry, and the chemical arts respectively; to direct and superintend, with the approbation of the managers, the construction of apparatus necessary for their lectures, and of other models and experimental machines proper to be placed in the repository; to collect such information as is requisite for these purposes; and to provide jointly sufficient matter for the publication of the Journals. The Superintendent of the House is charged with the regulation of its internal economy; and the Director of the Laboratory is empowered to make such experiments in it as he may judge likely to promote the views of the Institution. The clerk is required to attend in the house in general from nine to five, and on the evenings when lectures are delivered from seven to nine; but in particular to be never absent between twelve and four; to be ready every day at one o’clock, to show the various parts of the house to all persons who are entitled to admission; to inspect and arrange the library, to receive payment of subscriptions, to deliver tickets, and to keep all the accounts, under the direction of the managers and of the Superintendent of the House. The mathematical instrument maker, and other workmen in the immediate service of the Institution, are employed in the construction and repair of apparatus for the lectures and for the repository. The Superintendent of the Workshops assists also in the experiments exhibited by the professors in their lectures, and has the charge of the preparation of all necessary apparatus. Besides these officers, and the domestic servants of the house, six workmen are at present constantly employed in various departments of the Institution. Such persons as are desirous of becoming proprietors of the Royal Institution, or subscribers for life, or for any number of years, must be nominated by one of the managers, at a meeting prior to that in which they are elected; but in cases of emergency they may receive temporary tickets of admission as soon as they are nominated, paying their subscriptions, to be returned in case of non-election. A proprietor pays at present 80 guineas. He receives two transferable tickets of admission to the lectures and to the house in general; but such tickets do not admit the bearer to the reading rooms, unless they have been personally transferred to him, with the consent of the managers, for a time not less than a year. Subscribers for life pay 20 guineas, and annual subscribers 3 guineas a year. Their tickets admit the possessors to all parts of the house, but they are not transferable.