36 



SCIENTIFIC NEW^S. 



[April 1st, 1887. 



Tabic I. showing the number of feet run of pipe, 4 inches diameter, 

 which each boiler is estimated to heat. 



According to IVIr. C. Hood, F.R.S.,* experiments have 

 shown that the water contained in an iron pipe of 4 inches 

 diameter internally, and 4^ inches externally, loses '851 of 

 a degree (F.) of heat per minute, when its temperature is 

 125° above that of the surrounding air. Therefore, one 

 foot in length of pipe 4 inches internal diameter will heat 

 222 cubic feet of air one degree per minute, when the 

 difference between the temperature of the pipe and the air 

 is 125°. Taking this as a basis, we then have the following 

 rule for determining the length in feet run of iron piping 

 required for heating a given volume of air. Rule : Multiply 

 the volume of air in cubic feet to be warmed per minute by 

 the difference between the maximum temperature required 



* "A Practical Treatise on Warming Buildings, etc.," by Charles 

 Hood. F.R.S. E. and F. N. Spon, London, 



in the room and the temperature of the external air ; then 

 divide this product by the difference between the proposed 

 temperature of the room and of the pipes ; and finally mul- 

 tiply this result by i'i2 for pipes 2 inches diameter, by "75 

 for pipes 3 inches diameter, and by '56 for pipes 4 inches 

 diameter. For example, if 200 cubic feet of air are to be 

 warmed per minute, if the difference between the internal 

 temperature required and the external temperature is 30° F., 

 and if the difference between the proposed temperature of 

 the room and of the pipes is 90°, we shall then have 

 200 c. ft. X 30° 



90 



= 66"6 to be multiplied 



by i'i2 for pipes 2 ins. diameter=74| feet run. 

 „ -75 „ 3 „ =50 ,, 



„ -56 „ 4 . „ =37i 



For ordinary purposes it will, however, be sufficiently 

 accurate to take the figures given in Table II., in which will 

 be found the approximate lengths of piping required for 

 every 1000 cubic feet of space to be heated. 



Fig. 17. 



Table II. showing the approximate lengths of ^piping 2, 3, and 

 4 inches diameter requij'edfor every 1000 cubic feet of space 

 to be heated. 



Description of Buildings. 



Churches and large pub- 

 He rooms 



Schools and lecture- 

 rooms 



Dwelling-rooms 



Halls, shops, waiting- 

 rooms, etc 



Workrooms, manufac- 

 tories, etc 



Dryirg-rooms for wet 

 linen (when empty) ... 



Drying-rooms for paper, 

 leather, etc 



Greenhouses and conser- 

 vatories 



Graperies and stove- 

 houses 



Pineries, hot-houses, etc. 



Dairies, etc 



Tempera- 

 quired!" 



55° F. 



14 ft. run 



Pipe 3 ins. 

 diameter. 



9 ft. run 

 9 =, 



7 ft. run 

 7 



It may be mentioned that pipes 4 inches diameter are 

 best for horticultural purposes, but that smaller pipes are 

 generally better for other work. 



{To be continued) 



