19191 RURAL ENGINEERING. 291 



coiisiderubly the size of the drops. The greater the number of supply hoh\s 

 iit the edge of the directing disli, the greater was the decrease in the angle 

 of discharge, the narrower the width of the ring, and the larger the drops. 

 One supply hole was not sufficient as a one-sided cone was produced. Two 

 supply holes if located properly and of the right dimensions produced a spray 

 that was perfectly distributed. The presence of a post on the directing disk 

 decreased the angle of discharge, narrowed the width of the ring, and pro- 

 duced a more evenly distributed spray. A thick disk was found to reduce 

 greatly the angle of discharge, narrow the width of the ring, and increase the 

 size of the spray particles. Burrs in the outlet orifice, orifices that were oblong 

 in shape or not properly centered, disks that fitted loosely in the caps, or 

 cracks near the holes in the directing disk were responsible for a great deal 

 of the imperfections found in this study since they produced an unevenly 

 distributed spray. 



With reference to factors influencing the rate of discharge, it was found that 

 an increase in the area of the outlet orifice gave a greater rate of discharge. 

 The increase per unit of area was found to vary inversely with the area of the 

 orifice. An increase in pressure resulted in a gi'eater rate of discharge. No 

 general rule can be given for the increase for all nozzles except that as the pres- 

 sure is doubled the discharge is greater by 1.4 times. In most cases a deeper 

 eddy chamber increased the rate of discharge, which varied with the size of 

 the outlet orifice. Exceptions were found where a deeper eddy chamber re- 

 duced the rate of discharge to a certain point, and tlien an increase began to 

 show. Widening the eddy chamber was found to increase only slightly the 

 rate of discharge, the rate of increase varying inversely with the size of the 

 outlet orifice. Within certain limits, the greater the area of the supply holes 

 in the directing disc the greater was the rate of discharge. A supply hole placed 

 in the center of the directing disc was found to have much more influence on 

 the rate of discharge than did a corresponding area located at the outer edge. 

 An increase in the angle of the supply holes in the directing disc gave a greater 

 rate of discharge, the increase varying with the size of the outlet orifice. 

 Placing a post on the center of the directing disc just under the outlet orifice 

 increased the rate of discharge. A thick discharge disc diminished the capacity 

 of the nozzle. An angle on the nozzle, or a strainer just behind the directing 

 disc, was found to reduce the rate of discharge by increasing friction. Burrs 

 in the outlet orifices, or orifices that were not perfectly smooth and round, 

 greatly influencetl the rate of dischai'ge, the amount depending on the imper- 

 fection. 



Influence of silo-wall construction on freezing of silag'e (Iowa Sta. Rpt. 

 1918, p. 9).- — Temperature readings have been taken for five winter seasons 

 in three silos on the college campus constructed of wood stave, monolithic con- 

 crete, and hollow tile. In each silo thermometers were placed at the inside of 

 the north wall and also in the central part of the silo. The purpose of the work 

 was to find out which type of silo wall afforded the greatest protection from 

 freezing. 



The results show that during cold weather the temperature at the inside of 

 the north wall of the silo is only a little warmer than the outside temperature 

 with any of the silo walls tested. The difference between mean temperatures 

 at the north wall in different silos was seldom as much as 2° F. and was not 

 always in favor of the same type of silo. It is concluded that there is no 

 practical difference between the insulating properties of these three types of 

 Bilo wall, and that under the same conditions the same amount of freezing may 

 be expected in them. 



