_The Art of making a room comfortably warm_, does not consist merely in making a very large Fire in it--but depends as much on the keeping of cold air out--this is best done by _Double Windows_, see page 91, and double Doors,--at least take care that your Sashes fit close,--that the beads of the window frames are tight--stop the aperture between the skirting boards and the floor with putty--and list the Doors. We suppose it almost needless to say that every room in the house should be thoroughly ventilated[47] by a current of fresh Air--at least once every day, when the weather is not very damp--or cold. By making a Fire accordingly--this may be done almost every Day in the Year. If You leave the Door open for _Five_ minutes--it will let in more cold air than your Fire can make warm in _Fifteen_--therefore, initiate your Domestics in these first principles of the _Economy of Caloric_,--and when the Weather is cold, caution them to keep Doors shut. A regular Temperature may be preserved by a simple contrivance attached to a Thermometer, which will open an aperture to admit the external air--when the apartment is heated above the degree desired (_i. e._ about 60 for common constitutions,) and exclude it when it falls below it. A Room, which is in constant occupation all day--may be occasionally _pumped_ by moving the door backward and forward for several minutes. We do not advise Invalids to indulge themselves in heating their rooms to a higher temperature[48] than from 60 to 65.--Those who have resided the best part of their Life in warm climates--will like the latter best. While we recommend the Aged and Infirm to be kept comfortably warm--they must at the same time cautiously avoid excess of heat. When the Thermometer tells them that the external air is under 60,--whether it be in July, or in January,--those who are susceptible of Cold, must tell their Servants to keep a small fire--especially if the Weather be at the same time damp. Those who, from caprice, or parsimony,--instead of obeying this comfortable and salutary precept, sit shivering and murmuring, and refuse to employ the Coal-merchant, as a substitute for the Sun--may soon spend in Physic, more than they have saved in Fuel. By raising the temperature of my Room to about 65, taking a full dose of Epsom Salts, and a Broth Diet, and retiring to rest an hour sooner than usual, I have often very speedily got rid of _Colds_, &c. The following _Plan of Lighting and managing a Fire_, has been attended with great comfort and convenience to myself, (particularly at the beginning and the end of winter, when a very small fire is sufficient), and I think considerable saving of coals.