1507.] THOMSON— PROGRESS OF THE ISTHMIAN CANAL. 133 



of construction and supply. Notwithstanding this fact, a large 

 part of the cast iron used in the foundries in the zone is taken from 

 the French scrap. It is possible that the light rails of the rail- 

 ways used by the French in construction, may become available as 

 reenforcing material for concrete to be used in locks, or the like. 

 Doubtless in time an opportunity may arise for collecting this valu- 

 able debris, consisting usually of high grade metal. 



The question of health on the Isthmus of Panama is of vital 

 importance in the prosecution of the work. In times past, the 

 experience of the French company in regard to the spread of disease, 

 and in the consequent mortality, was so bad that the region became 

 a by-word for unhealthfulness and danger to life. This was, how- 

 ever, before modern methods of sanitation were known or prac- 

 ticed ; and before the modes of transmission of the germs of malaria, 

 yellow fever and severe intestinal disorders had become known. As 

 soon as certain species of mosquito were known to be intermediate 

 hosts for the organisms to which malaria and yellow fever are due, 

 the problem of canal construction was seen to be in a large degree 

 dependent on getting rid of these culture-charged insect pests. 

 Throughout the Canal Zone the evidences of success in this direc- 

 tion are palpable. Under the direction of Colonel Gorgas, who has 

 charge of the sanitation of the zone, it has been rendered much 

 safer than many localities in our southern states. What menace 

 there is, is not within the zone, but arises from the possibility of 

 introduction from the outside. A most admirable system has been 

 put into practice, including medical inspection, distribution of medi- 

 cine, drainage, fumigation, mosquito brigades and general sanita- 

 tion, such as abatement of nuisances, removal of offal and garbage, 

 clearing of land, burning of rank vegetation, etc. The whole is a 

 splendid example of the application of scientfic principles which 

 might well be copied in many places. The first evidences were found 

 at Colon in the filling in of low ground, the paving of streets and 

 improved drainage. Again at Gatun, the tropical jungle had been 

 cleared away almost to bare ground, especially around the habita- 

 tions and where men were at work. Drainage channels had also 

 been dug. While a few tent houses were still in use there, these 

 were soon to be replaced by a type of dwelling now usual in the 



