Another place that should receive attention is the city dumping ground, which frequently serves as an incubator for rats, and these soon overflow into near-by sections of the city. A study should be made of methods of disposing of waste materials and a system put into effect that will meet the requirements of the city and insure the destruction, removal, or adequate covering of all such food for rats. Any other conditions that may be found favorable for the breeding of rats, whether on public or on private property, should be declared a public nuisance and ordered corrected. MODEL RAT-PROOFING ORDINANCES The samples or models of rat-proofing and garbage-removal ordinances here given were prepared by the United States Public Health Service as a result of its experience in combating bubonic plague in several coastal cities. They have, in substance, been adopted and put into practice by a number of cities and have been found practicable. They should be applicable to any city after necessary allowance and possible changes have been made to conform to local conditions and constitutional considerations. AN ORDINANCE DEFINING RAT PROOFING OF ALL BUILDINGS[3] [3] U. S. Pub. Health Serv. Bul. 121, Preliminary Report on Proposed Antiplague Measures in Massachusetts. Section 1. _Be it ordained, etc._, That it shall be unlawful for any person, firm, or corporation hereafter to construct any building, outhouse, or other superstructure, stable, lot, open area, or other premise, sidewalk, street, or alley, or to repair or remodel the same to an extent of -------- per cent of cost of construction within the city of --------, unless the same shall be rat proofed in the manner hereinafter provided for. Sec. 2. _Be it further ordained, etc._, That for the purpose of rat proofing all buildings, outhouses, and other superstructures in the city of --------, except stables, shall be divided into two classes, to wit, class A and class B, and the same shall be rat proofed in the manner following, to wit: