HOUSEHOLD. 



207 



bloTving into the room -nrill injuriously 

 affect the instrument — it will cause the 

 highly seasoned wood of ftib casing 

 and interior to swell, and the metal 

 parts to rust. The ivory on the keys 

 will keep whiter if the lid is kept open 

 permitting exposure to the light; but 

 in sweeping or dusting the lid should 

 'be closed and the piano covered with 

 a cloth, to exclude dust. TZ>on't load 

 the top of a piano with bric-a-fbrac, 

 some of which may rattle and give 

 the impression something Is loose in- 



side. Pins, coins and other articles 

 are sometimes unconsciously allowed 

 to drop into it; these eoo are sources 

 of trouble. A piano is kept in best 

 condition if a tuner is employed to 

 go over it in the fall after the furnace 

 fire is lighted, and again in the spring 

 when it is time to let the fires out and 

 open up the house. Entrust such 

 work only to a man you know to be 

 competent, but if you cannot find such, 

 it would be better to write the maker 

 of the instrument. 



Hot-air Heating 



Some of the best engineering skill 

 of modern days has been applied to 

 the problem of the application of the 

 second great principle of heating — 

 that of supplying heat to a number of 

 rooms from a centralized plant. The 

 first application of this principle was 

 probably the hot-air furnace. This 

 consists essentially of the furnace it- 

 self, which is inclosed almost entirely 

 in a sheet-iron case, with sheet-iron 

 ducts leading therefrom to the various 

 rooms to be heated; to fill the place 

 of the air that is forced through these 

 pipes !by convection currents, cold air 

 is brought into the case through a 

 large sheet-iron duct, called the cold- 

 air duct. 



Hot-air furnaces are all quite 

 similar. diiTering only in the design 

 and arrangement of the parts; they 

 are all the same in consiting of a steel 

 or cast-iron case, with firebox, grate, 

 and ashpit. Some are fed through a 

 door in the side, the fuel being thrown 

 directly Into the firebox; others have 

 special arrangements so that the fuel, 

 which is comparatively small in size, 

 is sunplied from below; those possess- 

 ing this feature are known as under- 

 feed furnaces. The fuel used in hot- 

 air furnaces is almost always coal, 

 either bituminous or anthracite. 



Two distinct types of pipes are used 

 for conducting the heated air to the 

 rooms: first, those which are nearly 

 horizontal and lead fr(ftn the top of 

 the furnace casing — these are usually 

 round and made of a sinsrle thickness 

 of bright tin wrapped with two or 

 more thicknesses of asbestos to pre- 

 vent loss of heat, and are called lead- 

 ers; they should, if possible, be erect- 

 ed with an ascending pitch of one 

 incfh to one foot; second, rectangular 



vertical pipes or raisers, termed 

 stacks, made in such sizes as will fit 

 in the partitions of buildings and to 

 which the leaders connect. At the 

 bottom of the stack is an enlarged 

 section called the boot, which is pro- 

 vided with a collar for connection to 

 the leader. At the top of the stack is 

 a rectangular chamber into which the 

 register box fitted. To lessen fire 

 risk, these boxes should be made with 

 double walls. Each leader should have 

 a damper near the furnace, so that 

 when necessary or desirable it may 

 be closed; the nearer the damper is 

 to the furnace end of the leader, the 

 less will be the danger of superheat- 

 ing. 



Provision should be made for eva- 

 porating water in the air chamber, to 

 moisten the air forced through the 

 house; most furnaces are equipped 

 with a pan for this very purpose, 

 which is an important one, since 

 warm air requires more moisture 

 Ihan cold to maintain a comfortable 

 degree of saturation. It is a generally 

 accepted but mistaken belief that heat 

 supplied by a hot-air furnace is neces< 

 sarily a dry heat; all that is neces- 

 sary is to pass the heated air over 

 water. 



The hot-air furnace system of heat- 

 ing possesses certain advantages, 

 principal among which is the readi- 

 ness with which the temperature can 

 be raised. In cost it is much below 

 that of steam or hot-water heating, 

 two systems with which it is compar- 

 able, and it requires no care to pre- 

 vent bursting of pipes or boiler from 

 freezing. Unless the construction is 

 is good, and the erection has been 

 carefully made, combustion gases are 

 likely to be delivered to the rooms, 



