468 SCIENCE OF HOME AND COMMUNITY 



8. Copy the following table and write in it the answers to 

 questions 9, 10, n. 



9. Which birds on the chart do very much more harm than 

 good, that is, have the debit column fifty per cent or more 

 greater than the credit column? Put these in the first column. 



10. With what birds are the good and harm done about the 

 same, that is, not more than ten per cent difference ? Put these 

 in the second column. 



11. What birds are decidedly beneficial, that is, have the 

 credit column fifty per cent or more greater than the debit 

 column ? Put these in the last column. 



12. Arrange the birds according to the ratio between the 

 good and harm done. Place the cuckoo and oriolo at the head 

 of the list. For the others divide the percentage of good done 

 by the percentage of harm done. For example, for the chipping 

 sparrow divide 81 by 3 (27). Do the same with the others and 

 arrange them in order, the bird with the largest number first. 

 Which five birds stand first in the list ? Which five last ? 



13. (Optional.) If you wish you may make a chart from 

 this table similar to the one in Figure 183. This chart is to repre- 

 sent the ratio between the good and harm done. Let one inch 

 represent 5. Then for the chipping sparrow draw a line 5$ (Y) 

 inches long. In a similar way draw lines for the other birds, 

 arranging them in the order of the length of the line, the longest 

 first. Make the lines for the cuckoo and oriole two inches and 

 one inch, respectively, longer than that for the chipping sparrow 



FIELD EXERCISE 10 



Purpose. To learn what beneficial birds are common in your 

 locality. 



Directions, i. In order to find what birds are common in 

 the locality, field trips may be taken with the purpose of identify- 



