WE learn from A.E.G. Progress for October that many hotel, boarding-house, and convalescent-home keepers now instal in their bedrooms a special slot meter to collect the cost of the electric energy consumed by the visitor. It is not uncommon for travellers to carry about with them all kinds of portable electrical appliances which are readily connected to the plugs in the bedroom, notwithstanding the printed regulations to the contrary. This sometimes leads to the blowing of fuses and is a source of fire risk to the building. It is therefore now not uncommon to put slot meters in the bedrooms, so that by the insertion of a coin the guest purchases a given amount of energy. Unlike an ordinary prepayment meter, the coin mechanism can be returned to the ‘off’ position by resetting a simple device. In this way the new visitor cannot consume at the expense of the previous one any energy that still may be available. The resetting device is actuated by a key, kept by the proprietor, who cancels for his own benefit the credit still due to the departing visitor. The company which makes this meter suggests that the constant source of revenue obtained in this way should be utilised to make the rooms more comfortable, and furnish them with plug points for all kinds of electric devices.