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danger to the human population. For this reason the sewer should 

 be the last structure in a municipality to be made rat proof. The 

 movements and migrations of rats should be controlled to the extent 

 of making corner catch basins their sole means of entrance and exit 

 to sewers. The small and large iron-pipe mains require no attention 

 in this respect, but where mains are constructed of brick, and espe- 

 cially where they are old and in bad repair, they should be repaired, 

 all rat runs leading from the sewer walls being stopped up and all 

 blind sewers being closed. By this means there will be prevented 

 the breeding of rats in these areas. 



The rat proofing of catch basins by any method that would not 

 also block the entrance to the basin seems hardly possible. Properly 

 trapped basins, however, will be found almost as effective and just 

 as desirable. 



To attain efficient rat proofing requires necessary laws or ordinances 

 and public sentiment favoring their enforcement. Dead-letter laws 

 that form no small part of many city statutes attest the fact that 

 favorable public opinion is almost indispensable to their enforcement. 

 However, well-drafted laws, clear and specific in requirement and 

 impartially and consistently enforced, inevitably lessen and destroy 

 opposition. 



In the foregoing are contained general principles necessary to rat 

 proofing in the case of an outbreak of plague. Due allowance will 

 have to be made, however, for local conditions, and special consid- 

 erations as they arise, as no unvarying plan will be practical of appli- 

 cation in every instance. 



CHOICE OF ARCHITECTURE AND BUILDING MATERIALS. 



Cities and countries have from time to time wholly revolutionized 

 their type of buildings and constructive materials for either commer- 

 cial or aesthetic reasons. It is suggested that ports having trade 

 relations with countries where plague prevails should bear in mind 

 the advisability of taking advantage of this fact and revise their 

 building laws with the view to rendering all new buildings rat proof. 



Concrete has been advocated for purposes of rat proofing because 

 of its durability and relative cheapness. Concrete flooring or side 

 walls can be made more durable, however, by embedding therein 

 steel netting of 1 or 2 inch mesh. By this method the cost of con- 

 struction will probably be reduced, as a thinner layer of concrete 

 would be sufficient, and the metal would be protected, thereby adding 

 stability. Such construction at the same time would be doubly rat 

 proof. 



