272 



Temperature in middle of steam pipe 339.05° F 



Temperature in saddle 327.87° F 



Pressure in dry pipe by gauge 70 lbs 



Temperature of saturated steam at pressure in dry pipe .... 315.68° F 

 Approximate time occupied by the steam in passing the steam 



pipe 0.1 seconds 



It will be seen that the temperature of the steam was increased 4.4° F in 

 passing half the length of the branch pipe, which is equivalent to a gain 

 of 8.8° F in its passage through the whole length of the branch pipe. The 

 transfer of a quantity of heat represented by this increase of temperature 

 would affect moist steam by increasing its dryness about 0.5 of 1 per cent., 

 an amount too small to affect the efficiency of the whole machine to any 

 measureable extent. 



The thermometer in the saddle indicated a temperature of 9.4° F lower 

 than the temperature in the T-head, and 18.2° lower than the presumable 

 temperature at the end of the steam pipe, so that, from the T-head to the 

 cylinder, there is no gain, but an actual loss of heat by the steam. This 

 effect is to be accounted for in the fact that the mean temperature within 

 the cylinders is much lower than the temperature of the incoming steam, 

 which, combined with the effect of radiation from the saddle, operates to 

 lower the temperature of the iron which surrounds the steam in its pas- 

 sage through the saddle. It is certainly clear that the cooling effect of the 

 saddle more than offsets the gain in heating effect secured from the smoke 

 box. 



The conditions were varied and all of the work repeated several times 

 with the same general results. The figures given represent the test giving 

 the greatest heating effect. 



Enlarging the pipes within the smoke box would have a beneficial ef- 

 fect in increasing the action herein considered, since it would add to the 

 extent of heating surface and lengthen the time occupied by the steam in 

 passing the same, but, as a practical matter, a limit to such enlargement 

 is soon reached. 



As affecting the reliability of results, it may be said that the thermome- 

 ters used have a range of from 100 C to 200 C and read to i of a degree. 

 They were inserted in long tubes, and at the T-head and at the middle of 

 the steam pipe these tubes were protected by allowing steam to flow past 

 them under pressure into the atmosphere. Before being used the ther- 

 mometers were carefully compared when in the identical tubes used upon 



