SUGGESTIONS TO TEACHERS 199 



five feet higher. A mile farther are the Pedro Miguel 

 Locks, which consist of a single pair, with a Hft of 

 thirty feet. 



The Pacific half of the mid-section should be shown 

 as a narrow cut through hills, which extends nine miles 

 to Gatun Lake. The highest of these hills stand approx- 

 imately one thousand feet above sea level, although the 

 pass through which the Canal was dug was only three 

 hundred feet above sea level. The relation of the 

 Canal to Gatun Lake and to Barro Colorado (Jungle) 

 Island as well as to these other features may be seen 

 on the map on page 11. A generalized profile is given 

 as an aid in the supervision of such efforts (page 15). 



Insect-borne diseases. When the engineering diffi- 

 culties of digging the Panama Canal have been firmly 

 fixed, the teacher should make a point of the greater 

 obstacles involved in the insect-borne diseases as out- 

 lined in the last chapter. The story of Colonel Gorgas 

 himself (Sanitation in Panama, 19 15) may be read 

 and told in as much detail as time permits. • 



Study of climate. Almost all the differences between 

 tropical and temperate climates may be truthfully 

 brought out in such a story. Some of these differences 

 are illustrated in the table on page 200, taken from 

 a report by Mr. R. Z. Kirkpatrick, chief of the Division 

 of Hydrography and Meteorology of the Canal Zone. 



Rainy season. In parts of the rainy tropics there 

 is no cessation of the rainy season, but in much of 

 this region, the world over, the rains are interrupted 

 for a longer or shorter dry season. Thus in Panama 

 during January, February, or March there is about 

 the same quantity of rain that we have in Chicago in 



