8 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 



results usually obtained by the use of the common tables have tended 

 to blind the users to this cause of occasional bad results. The use of 

 a better calculated table will in no way improve the results under these 

 normal conditions. 



Construction of the New Tables 



The following method was employed in the construction of the 

 tables given below. The dose column was made by using the num- 

 bers 5, 6, 7, 8, 9, and 10 oz, and halving and doubling the same so as to 

 maintain the same ratios through the whole length of the column. The 

 average difference is almost exactly 14% increase or 15% decrease. 



The next column gives the dimensions in feet for tents in which the 

 distance around equals the distance over the top and is so calculated 

 that there should be. a difference of 14% in the doses the adjacent 

 sizes should receive. The calculation 1 of this column is the most im- 

 portant element of the whole table. 



Three methods of calculation have been proposed, viz., volumne, 

 area and leakage. 



The volumne method was used in all the older tables and would 

 require a little less than 5% increase in size for each line on the table. 



The area method, requiring a little over 7% per line is that now 

 almost universally employed and is somewhat justified on the ground 

 that it approximately allows for the average leakage of fumigation 

 tent material. 



The leakage method used in this table allows accurately for leak- 

 age. The average increase in size between 22 and 44 feet is precisely 

 the same as by the area method, but the upper end of the table ap- 

 proaches nearer the 5% and the lower toward the 14%. This method 

 conforms with the actual practice of fumigators who find it necessary 

 to arbitrarily modify the two ends of the common table. 



The remainder of the table gives the dimensions of trees of diff- 

 erent shapes but approximately the same sizes and which should there- 

 fore receive the same doses. The distance over the top of the tent is 

 given in black type, the numbers simply being arranged consecutively 

 and beneath each the corresponding circumferences are written. These 

 differ by fours. 



Accuracy of the Tables 



All fractional parts have been omitted in these tables. The dose 

 series is actually 5, 5.7, 6.5, 7.5, 8.7, and 10 oz. A slightly more 

 accurate continuation would be 11, 13, 15, 18, 20, 22, 26, 30, 35, and 



