214 THE WONDERFUL CENTURY. CHAP. xvm. 



under the very worst sanitary conditions as regards ven- 

 tilation, water supply, and general cleanliness. Till 

 about 250 years ago it was as common in England as 

 small-pox has been during the present century, but a 

 very partial and limited advance in healthy conditions 

 of life entirely abolished it, its place being to some 

 extent taken by small-pox, cholera, and fevers. The 

 exact mode by which all these diseases spread is not 

 known; cholera, diphtheria, and enteric fever are be- 

 lieved to be communicated through the dejecta from 

 the patient contaminating drinking water. The other 

 diseases are spread either by bodily contact or by trans- 

 mission of germs through the air; but with all of them 

 there must be conditions favoring their reception and 

 increase. Not only are many persons apparently insus- 

 ceptible through life to some of these diseases, but all 

 the evidence goes to show that, if the whole population 

 of a country lived under thoroughly healthy conditions 

 as regards pure air, pure water, and wholesome food, 

 none of them could ever obtain a footing, and they would 

 die out as completely as the plague and leprosy have 

 died out, though both were once so prevalent in 

 England. 



But during the last century there was no such knowl- 

 edge, and no general belief in the efficacy of simple, 

 healthy conditions of life as the only effectual safeguard 

 against these diseases. Small-pox, although then, as 

 now, an epidemic disease and of very varying degrees 

 of virulence, was much dreaded, because, owing chiefly 

 to improper treatment, it was often fatal, and still more 

 often produced disfigurement or even blindness. When, 

 therefore, the method of inoculation was introduced 



