The chief office in London is divided into six principal departments, each under the charge of a chief officer. These heads of departments are severally responsible to the Postmaster-General for the efficiency and discipline of their respective branches. Something like the same arrangement, though on a much smaller scale, is preserved in the less-important chief offices of Edinburgh and Dublin. The branches in question consist of--(1) The Secretary's Office; (2) The Solicitor's Office; (3) The Mail Office; (4) The Receiver and Accountant-General's Office; (5) The Money-order Office; and (6) The Circulation Office. 1. _The Secretary's Office_ exercises a general _surveillance_ over all the other departments of the Post-Office, including, of course, all provincial offices. It is the medium of communication with the Lords of the Treasury, and also with the public. All important matters originating in other branches, or in country offices, pass through this office to the Postmaster-General, returning through the same channel. In 1763, the secretaries of the Post-Office had one clerk and two supernumerary clerks assigned to them. Now, the three secretaries are assisted in their duties by one chief clerk, one principal clerk for foreign and colonial business, sixteen senior clerks, and thirty-eight clerks in other two classes. There is also a force of nineteen supplementary clerks, five official paper-keepers, and nineteen messengers.[145] 2. _The Solicitor's Office_, as its name implies, deals with the law business of the Post-Office. It gives employment to a solicitor, an assistant-solicitor, and four clerks. 3. _The Mail Office_ has to do with all matters connected with the transmission of mails, whether the conveyance be by railroad, water, or stage-coach. Attached to this office are the travelling post-offices of the country, which are under its exclusive management. The Mail Office arranges with the different railway companies for the conveyance of the mails, in the contracts for which are included provision for the employment of post-offices fitted up in railway-carriages; it also looks to the proper performance of each post-office contract embracing mail-conveyance. The staff of the Mail Office comprises an inspector-general of mails, a deputy inspector-general, two principal clerks, and twenty-one clerks in three classes. The connexion between the Mail Office in London and its important adjuncts, the travelling post-offices, is kept up by a staff of five inspectors of mails (three employed in England, one in Scotland, and one in Ireland), a supervisor of mail-bag apparatus, and several subordinate officers. The travelling offices employ a force of 54 clerks in three classes, and 139 sorters in four classes.