Gkeenhouse Notes. 



171 



ible effect, while if only the readings taken with no pressure are aver- 

 aged, as in the last part, the difference is very great. 



This shows that crooks and angles impede the circulation of steam 

 under pressure much less than of hot water, and emphasizes the utility 

 of pressure in forcing steam through long and crooked circuits; and 

 it also enforces the great value of steam over hot water in all places 

 where difficult runs are necessary, and where additions and alterations 

 are likely to be made to the house. 



When the long run was added, March 16th, it was necessary to 

 raise the expansion tank above the roof, which increased the water 

 pressure to an average of 3^ pounds. The average difference 

 between the temperature at the boiler and the east end of the middle 

 riser, was less in this test than in the previous one with hot water, 

 after the addition of the extra crook, but this may have been purely 

 accidental, rather than due to any beneficial effect of the greater pres- 

 sure afforded to the tank. 



Time required to heat up each system. — 



Hot Water. 



Time 



Boiler thermometer No. 1 . 

 Boiler thermometer No 2. 

 Boilor thermometer No 3 

 Boiler thermometer No. 4 

 Boiler thermometer No 5. 

 Boiler thermometer No. 6, 

 Boiler thermometer No. 7, 



00 



o ^ 



® 



.fcl 



b 



11.40 

 89° 



78° 

 61° 

 82° 

 68° 

 72° 

 59° 



CO 



u 

 3 

 o 



« 



.Sa 



1.10 

 204° 

 180° 

 155° 

 187° 

 154° 

 135° 

 147° 



Steam. 



* Low temperatures can not be accurately given in all cases, because the thermometers were 

 inserted into the tubes so far that they could not be read below about 50 degrees. 



