HOUSEHOLD BACTERIOLOGY. 



Dust-proof 

 Boom or 



House 



Necessity 

 of Dust 



exclaimed, "Where does all the dust come from?" If 

 a house be thoroughly cleaned from cellar floor to attic 

 ridge, tightly closed for months or years, when re- 

 opened dust will be found in great quantities. 



This is true even in the country, where perhaps a 

 single house, removed from the highway, stands sur- 

 rounded by grass and trees. 



The "housekeeping" of ships includes dusting. 

 The officers' quarters of the government ships are 

 dusted regularly, although land may not be seen for 

 months at a time. 



Scientists have tried to get a dust-proof room or 

 house in which to carry on their experiments. This 

 has required attention to location and site, that there 

 should be no jar from traffic or vibration from winds ; 

 a careful preparation of the surrounding soil ; numer- 

 ous walls separated from each other and made largely 

 of glass, carefully joined and hermetically sealed. The 

 air admitted must be freed from its dust ; all clothes 

 ordinarily worn by the experimenter must be ex- 

 changed for garments especially prepared and cared 

 for, before he enters this to-be-dustless room. Even 

 then all surfaces need to be slightly moist, that any 

 stray speck of dust which has escaped all these guards 

 may be caught and held. 



Such conditions as these can never be secured in 

 ordinary life, so that dust will probably be present with 

 us always. Indeed, it is probable that were all dust 

 exterminated, life also would become extinct, for life 

 in its most efficient forms needs light, and Tyndall 



