STO 



562 



STO 



large tank, to 180°; and if this heat be I Now in the house, the dimensions of 

 imparted late in the evening, it will which are above given, if the lowest 

 retain its heat but little diminished until | temperature in the night be fixed at 50^, 

 the morning. The smoke, by means of and IC^ are allowed for winds, and the 

 a flue, may be made to impart heat to external air is supposed to be at zero or 

 the house, by passing through it, or of Fahrenheit, then 1175 multiplied 

 may at once enter the chimney or pipe I by 60*^, and the product divided by 2-1 , 

 attached to the summit of the boiler. ' the difference between 200 and CO, will 



Hot water in a tank is superior to the i give us the quotient 236 = to the sur- 

 same source of heat in pipes, because ' face of pipe required. Now the house 

 it is not liable to freeze ; and it is pre- ; being thirty feet long, five pipes of that 

 ferable to steam, because its heating length, and five inches in diameter, 

 power continues until the whole mass : will be about the proper quantity, 

 of water is cooled down to the tempe- | If hot water be employed instead of 

 rature of the hou&e, whereas steam . steam, the following proportions and 

 ceases to be generated as a source of, information, obtained from Mr. Rendle, 

 heat the moment the temperature falls j may be adopted confidently as guides, 

 below 212^. If steam be employed, J In a span roof propagating house, forty 

 Mr. Tredgold has given the following j feet long, thirteen feet broad, seven 

 rules for calculating the surface of I feet high in the centre, and four feet 

 pipe, the size of the boiler, the quan- high at the two fronts, having a super- 

 tity of fuel, and the quantity of ventila- ficial surface of glass amounting to 

 tion, required for a house thirty feet 538 square feet, Mr. Rendle has a tank 

 long, twelve feet wide, with the glass eighty-three feet long, running round 

 roof eight feet, length of the rafters three sides of the house, four feet wide 

 fourteen feet, height of the back wall i and about eight inches deep, and con- 

 fifieen feet. The surfiice of glass in ] sequently capable of containing nearly 

 this house will be seven hundred and j 300 cubic feet of hot water, though only 

 twenty feet superficial, viz., five hun-lhalf that quantity is used. This is 

 dred and forty feet in the front and roof, ' closely approaching to the size pointed 

 and one hundred and eighty feet in the i out, according to Mr. Tredgold's for- 

 ends. Now, half the vertical height, i mula. The mean temperature of a hot- 

 seven feet six inches, multiplied by the j water tank, will never be much above 

 length in feet, and added to one and a i 100^, so that for the sized house men- 

 half time the area of glass in feet, is tioned by that skillful engineer, the 

 equal to the cubic feet of air to be [ divisor must be 2- 1 times the difference 

 warmed in each minute when there are i between 100'^ and 60°, which gives as 

 no double doors. i the quotient 335 cubic feet. 



That is, 7.5 X 30+U X 720=1305 1 The tank in Mr. Rendle's propagating 

 cubic feet. But in a house with wooden house, is built lined with Roman ce- 

 bars and raflers, about one-tenth of this ment, and if the temperature at the 

 space will be occupied with woodwork, ! time of lighting the fire be 903,thetein- 

 which is so slow a conductor of heat, ; perature of the atmosphere of the house 

 that it will not suffer a sensible quan- 67^, and the temperature out of doors 

 tity to escape, therefore 130 feet may ' 50'^, the quantity of small coal or 

 be deducted, leaving the quantity to be I breeze required to raise the tempera- 

 warmed per minute = 1175 cubic feet, j ture of the water to 125^', is 28 pounds. 



To ascertain the surface of pipe re- : In twelve hours, the water cools after 

 quired to warm any given quantity of the fire has been extinguished, from 

 air, multiply the cubic feet of air to be i 125^ to 93°. 

 heated per minute, by the difference When steam is employed, tlie space 



between the temperature the house 

 to be kept at, and that of the external 

 air in degrees of Fahrenheit's thermo- 



for steam in the boiler is easily tbund 

 by multiplying the length of the pipe 

 feet, by the quantity of steam 



meter, and divide the product by 2-1, i foot in length of the pipe. 



the difference between 200, which is | Decimal parts of a 



the temperature of the steam pipes, and „" "J,""^;" '^!!!kL" cuIjic foot ot'sieara 



tlie temperature of the house: the quo- 

 tient will be the surface of cast iron 

 pipe required. 



in each footof pipe. 

 . 0.0545 

 . 0.1225 



