The General Post-office of the city is located on Nassau street, between Cedar and Liberty streets. It was formerly the Middle Dutch Church, and was built long before the Revolution. It was in the old wooden steeple of this building that Benjamin Franklin practiced those experiments in electricity, which have made his name immortal. When the British occupied the city, during the War for Independence, they occupied this church for military purposes. The building was very greatly injured by the rough usage to which it was put, by its sacrilegious occupants. The pews and pulpit were broken up for firewood, and the building was used first as a prison, and then as a riding school. It was repaired in 1790, and again used for religious services. Some years later, it was purchased by the Government, and fitted up as a post-office. The growing business of the office has made it necessary to make so many additions to the structure, that it is hard at present to distinguish the original plan of the edifice. The building is much too small to accommodate the business required to be transacted within its walls, and efforts are being made to secure the erection of a larger and handsomer building, at the lower end of the City Hall Park. It is supposed that the movement in this direction will be successful, though the Government would seem, by its delay in the matter, not to consider it a matter of much importance to accommodate the citizens of the metropolis in this respect.

The Post-office being situated so low down in the city, it has been found necessary to establish branches, called "Stations," in the upper part of the island. They are distinguished by the letters "A," "B," "C," etc. Many persons receive and mail their correspondence here. The drop letter system places an immense amount of business in the hands of these stations.

Street boxes, for letters, are scattered through the city. They are never more than a block or two apart, in any of the streets below Fifty-ninth street, and the distances are not very great in the other portions of the island. Letters dropped in these boxes are collected seven or eight times during the day, and there is a delivery of letters and papers by the postman every hour. These are left at the houses of the parties to whom they are addressed, without additional charge. The system is excellent, and is a great convenience to all classes of the population.