EAT-PBOOF BUILDTNG. 37 



rapidly extending to all kinds of buildings. Dwellings, dairies, 

 barns, stables, chicken houses, ice houses, bridges, dams, silos, tanks, 

 cisterns, root cellars, hotbeds, sidewalks, and curbs are now often 

 made wholly of cement. The processes of mixing and laying this 

 material require little skill or special knowledge, and workmen of 

 ordinary intelligence can successfully follow the plain directions 

 contained in handbooks of cement construction. Illustrated hand- 

 books are often furnished free by cement manufacturers. 



Many modern public buildings are so constructed that rats can find 

 no lodgment in the walls or foundations, and- yet in a few years, 

 through negligence, such buildings often become infested with the 

 pests. Sometimes drain pipes are left uncovered for hours at a time. 

 Often outer doors, especially those opening on alleys, are left ajar. 

 A common mistake is failure to screen basement windows which 

 must be opened for ventilation. In whatever way the intruders 

 are admitted, when once inside they proceed to intrench themselves 

 behind furniture or stores, and it is difficult to dislodge them. The 

 addition of inner doors to vestibules is an important precaution 

 against rats. The lower part of outer doors to public buildings, 

 especially markets, should be reinforced with light metal plates to 

 prevent the animals from gnawing through. 



In constructing dwelling houses the additional cost of making the 

 foundations rat-proof is slight as compared with the advantages. 

 The cellar walls should have concrete footings, and the walls them- 

 selves be laid in cement mortar. The cellar floor should be of 

 "medium" rather than "lean" concrete, and all water and drainpipes 

 should be surrounded with concrete. Even old cellars may be made 

 rat-proof at comparatively small expense. Rat holes may be per- 

 manently closed with a mixture of cement, sand, and broken glass, 

 or sharp bits of crockery or stone. 



On a foundation like the one described above, the walls of a wooden 

 dwelling also may be made rat-proof. The space between the sheath- 

 ing and lath, to the height of about a foot, should be filled with 

 concrete. Rats can not then gain access to the walls, and can enter 

 the dwelling only through doors or windows. Screening all basement 

 and cellar windows with wire netting is a most necessary precaution 

 to exclude rats. 



Rats sometimes gain access to houses by way of vines growing on 

 the outer walls and reaching to open windows, and the means by 

 which the animals come and go is a mystery to the household. Old 

 growths of Virginia creeper or ivy often furnish such ladders for rats. 



Rats often enter houses from sewers by way of soil pipes leading 

 into water-closets. A number of instances of this kind were reported 

 to the writer as having occurred in the city of Washington during 

 the past year. The careful construction of drains and the use of 



