30G WARMING AND VENTILATION. 



The air to be warmed by the heaters is taken from outside. A suflfi- 

 cient number of pipes in the aisles and passages admit the air through 

 numerous openings placed in the vertical faces of the walls, or in the 

 bases of the columns, a little above the floor, and not at the floor-level, 

 as is often wrongly done. 



During the summer season, the interior of churches, strongly heated 

 during the day by the action of the sun on the roof and through the 

 large windows, is often uncomfortable to stay in, especially in the morn- 

 ing. It would be easy to avoid this trouble by arranging a number of 

 windows to be opened at night, in .order to admit the fresh air, and 

 to be shut in the morning. The interior, thus cooled during the night, 

 would be less warmed during the day. 



These precautions, much neglected in France, where the heat of sum- 

 mer seldom proves unpleasant, are regularly carried out in Rome, where 

 it lasts a long time. A rule of the custodians of St. Peter's requires 

 that the windows of the upper galleries be opened every evening in 

 summer and closed every morning. 



What precedes only applies to ordinary churches ; but in the case of 

 chapels or subterranean churches, the interior height of which is very 

 limited and which are often occupied by a large number of worshippers 

 and fully lighted up, it becomes necessary to secure the renewal of air 

 and the removal of the hot gases arising from the lights. The plans 

 proposed in § 64 for night drawing-schools should then be adopted, 

 producing a renewal of air at least five or six times an hour. 



In churches where great ceremonies require the use of large canopies, 

 preventing the circulation of the air, and in which a great number of 

 candles occasion often an extraordinary elevation of temperature,* it is 

 very important that the construction should allow of forming, in the 

 upper or lateral portion, as many openings as possible in order to allow 

 the external air to flow in with a velocity which will be less the greater 

 the number of these openings and the more uniformly they are distrib- 

 uted. In tins way will be avoided the at times unendurable currents of 

 air produced by the doors and the elevation of temperature. 



In winter, at the time of thaws after great cold, especially in the 

 north, there is produced on the walls, and still more on the ceiling, a 

 condensation of vapor, which often produces a sort of rain that afl'ects 

 the paintings. In such cases, it would be well to carry the warm air 

 supplied' by the heaters at about from 140° to 115^ directly to the up- 

 per part of these edifices at the springing of the arches, in order to 

 keep the vapor arising from the people in the lower portions of the 

 church from condensing. 



RAILROAD-STATIONS. 



97. As an example of cases where it is proper to act contrary to the 

 general rules given before, we will specify the methods to be adopted for 



*In a great fnucral-ceremony at Notre-Dame, Paris, the heat was such that the wax- 

 tapers began to melt. 



