188 Agkicultural Experiment Station, Ithaca, N. Y. 



A corresponding rise in temperature with, increased pressure in 

 shown, but it is not altogether uniform. It appears That ^be &ame 

 temperature does not necessarily follow from the same pressure. 

 The following figures, deduced from the results, furnish a rough 

 estimate of the influence of pressure on the temperature inside 

 the risers at this distance, about twelve feet from rhe boiler : 



One pound of pressure increases the temperature one-third 

 degree. 



Two pounds of pressure increases the temperature three-fourths 

 degree. 



Three pounds of pressure increases the temperature flve-eiglitlis 



degree. 



Five pounds of pressure increases the temperature twelve-four- 

 teenths degree. 



It is to be noted that in general, pressure increases the tempera- 

 ture of the returns muck more than of the risers. The return 

 from A and B in nearly every case of pressure shows a tempera- 

 ture higlier than its general average at that point, wtdle the 

 exceptions are but few in the return from G and D. The return 

 from A and B is direct, uniting but two of the runs of these 

 houses, w hile that from houses C and D is from a slightly longer 

 circuit, and unites all the runs, so that doubtless more of the 

 steam is condensed in this latter case before reaching the point 

 where the thei-mometer is inserted. Its lower general average 

 indicates this. 



These figures give conclusive evidence of the utility of pressure 

 in forcing circulation through long cii'cuits. They also suggest 

 a question as to the economy of maintaining such a pressure as to 

 keep up a rapid circulation. It is evident that the condensation 

 of the steam in the returns liberates its latent heat where it must 

 be available in warming the houses. Whether this malies a 

 better use of the heat than to return the steam to the boiler uncon- 

 densed, allowing it to be again sent into the circuit without the 

 expenditure of fuel necessary to the production of this latent 

 heat, may be a question. The general observations show that 

 there is usually a higher house temperature w ith steam pressure, 

 when the outdoor temperature is above the same. It does not 



