272 MAN'S IMPROVEMENT OF HIS ENVIRONMENT 



Conclusion. — What is the annual cost of typhoid, tuberculosis, 

 and diarrheal diseases of children to the city of New York ? 



Problem 243 : What are the chief causes of death in a city ? 

 Method and Observations. — From the foregoing table deter- 

 mine : 



(1) The relation of the number of deaths from infectious dis- 

 eases to the total death rate. 



(2) The diseases which kill the most children. 



(3) The per cent who actually die of old age. 



Conclusion. — 1. What percentage of all people of the city die 

 from old age? 



2. What diseases kill most babies and children under five years 

 of age ? 



3. What diseases in the list might be influenced by alcohol? 



Problem 244 : To study the relation of the death rate to the 

 season. 



Method. — Study tables carefully in the following manner : 

 Note a given disease, as typhoid, and make a graph, using figures 

 given, to determine the number of cases reported and number of 

 deaths monthly in New York city. 



Conclusion. — Is typhoid equally prevalent all the year round ? 

 How do you account for its great prevalence in the fall? 



(The instructor should divide up the work so that each member 

 of the class will be responsible for a separate graph. A general 

 discussion may then be held on the relation of various diseases 

 to the city death rate. For example : What disease is responsible 

 for the greatest death rate ?) 



Problem 245 : To find a relation between flies and mortality. 



Method. — Refer to mortality tables published on pages 270, 

 271, and fill in the table on the opposite page. 



Observations. — With the aid of the given data, construct a 

 graph showing the prevalence of flies and number of deaths per 

 month for the dates given. (In making curves on cross section 

 paper let 1 cm. = 50 deaths, and 1 cm. = 200 flies.) 



Conclusion. — 1. Is there any relation between the prevalence 

 of flies and the number of deaths from diarrhea? 



