300 The Control of Mosquitoes 



and contend with leaks in the roofs also. At 

 times ten pottnds of sulphur per thousand cubic 

 feet of air space was used, to obtain a maximum 

 of fumes in a minimum of time, and allow for 

 leakage. 



Non-immunes stationed in the Canal Zone were 

 advised not to visit the terminal cities except 

 when absolutely necessary, because yellow fever 

 was more prevalent there than in the Zone. Even 

 the train schedule was changed on Sundays, to 

 make it inconvenient for American employees from 

 the Zone to remain long in the city of Panama. 

 The object was to keep non-immunes away from 

 the infected mosquitoes as much as possible. 



Two cases occurred in the Zone that were of 

 special interest. The first was at Paraiso ; the pa- 

 tient was a locomotive engineer, and he had not left 

 his home district except for about an hour and a 

 half during the period in which he could have 

 contracted yellow fever. On that occasion he had 

 traveled three nules from Paraiso to Culebra in his 

 engine cab, and arriving at Culebra, stepped out 

 of his machine and into the pay car, where he 

 remained only long enough to collect his pay. 

 He at once returned to Paraiso with his engine. 

 There was such a crowd moving about the pay car 

 and its vicinity, it was not probable that any 



