52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 52 



solution of sulphate of copper, five pounds to a barrel of fifty gallons 

 of water. This is also used in all running streams after the removal 

 of algas. 



Open ditches in which the water flows sluggishly have oil drip- 

 cans at their heads. These oil drip-cans are raised three feet above 

 the water to give a wide spread to each drop, and are arranged to 

 drop about twenty drops to the minute. The oil used is a rather 

 heavy dark grade, which costs the department $4.34 a barrel. x\bout 

 3,200 barrels of oil were used within the last year. 



All streams are kept free from alg?e and are kept within restricted 

 banks as far as possible ; this is done by blowing out the rapids or 

 falls to produce a uniform flow, and the edges are filled in by hand. 



All swamps, pools, or even temporary collections of water are oiled 

 at least weekly, and in the rainy season oftener ; this applies to the 

 smallest collection of water, even animal tracks, ruts from wagon 

 wheels, and crab-holes. It entails a great amount of work, which is 

 done by colored labor under continual supervision. 



All receptacles holding water must be screened or oiled. Water 

 barrels are screened by covering with a board with a small screened 

 opening in the center for the inflow. Below this board are two 

 screened holes for overflow, and the water is drawn from a faucet 

 at the bottom. Buckets and pails in daily use in a household are not 

 permitted to stand filled more than twenty-four hours. All tin cans, 

 bottles, etc., must be buried. No gutters are allowed on houses. 

 There is a daily inspection of all water receptacles, and weekly the 

 inspector at the head of the station must make a personal inspection 

 and report any receptacle found containing mosquito larvse. The 

 second offense, after a warning, means the arrest and fine of the 

 householder. 



All old machiner}', which is found in great quantity all over the 

 Canal Zone, left from the French occupation, is drained by punching 

 holes in any part that will hold water, or where this is not possible, 

 such places are filled with dirt. Even patent car couplings on the 

 trains in use nuist be inspected and oiled, as they are often found to 

 contain mosquito lam'.c. 



When an}' house or camp is found to contain any number of 

 mosquitoes, it is fumigated with sulphur by the dry method. All 

 cracks or openings are pasted over with paper ; enough pots, each 

 containing five pounds of sulphur, are placed at intervals on the 

 floors to make about one pot for each 1,000 cubic feet of space. 

 After fumigation, the house is left closed from three to four hours. 



All barracks, whether for white or black laborers, bachelor quar- 

 ters, married ([uarters, offices, churches, lodge-rooms, and other 



