10 BULLETIN NO. 161 



According to Prof. W. J. Humphreys, (h) of the U. S. 

 Weather Bureau, soot of the proper degree of fineness is several 

 thousand times more effective than carbon dioxide in intercept- 

 ing earth radiation. With smudge pots and coal baskets, only 

 a small percent of soot is produced, most of the fuel being 

 burned to carbon dioxide. 



ELECTRIC HEATERS 



To test the relative merits of the heat and smudge we de- 

 cided to do some heating by means of electricity, where no 

 smudge is liberated and note the effect and then add to the air 

 about the electric heaters carbon dioxide, and thereby see if the 

 smudge caused the air about the heaters to be warmer than it 

 was before it was added. The results of the heating done by 

 other investigators have been given in terms of the number of 

 heaters to the acre and the resulting rise in temperature- The 

 rise in temperature of course would depend on the rapidity with 

 which oil is burned and on the calorific value of the fuel. By 

 heating electrically we can readily control the amount of heat 

 supplied, and can determine just how much is being delivered 

 by reading the electrical measuring instruments. It was dis- 

 tinctly understood from the beginning that the cost of electrical 

 power is such that it would be impractical for the farmers to 

 heat their orchards in times of frost by means of electricity. 



We made some electric heaters of about ten kilowatt (121/2 

 horse power) capacity, this being about the capacity of the 

 gallon size oil smudge pots, by making coils out of No. 14 gal- 

 vanized iron wire and fastening these coils on porcelain insul- 

 ators that had been bolted to small iron frames, These heaters 

 cost $1-35 a piece. 



EXPERIMENT ON HEATING, WITH AND WITHOUT 

 SMUDGE INSIDE A LARGE BOX 



We took two large wooden boxes that had been used for 

 shipping expensive art pictures and which had therefore been 

 specially lined, being almost air tight, knocked the bottom out 

 of one and placed it on top of the other, giving us an inclosure 

 2^ by 4^ and TVs feet deep, which was nearly air ti?ht. Th's 

 box was taken out in the open air in the court of the Mechanic 

 Arts building of the College and four electric heaters were 

 placed in the bottom of it, the heaters being connected in series 

 so that the power consumption was but % horse power. Nine 



/h). Bui. Mt. Weather Obsy., 6, 1913. 



