512 Effects of Epidemics on Registers of Bk. ii. 



and then accidentally for one or two years a 

 small proportion, the effect would be a large pro- 

 portion of births to marriages in the registers 

 during these one or two years ; and on the con- 

 trary, if for four or five years few marriages com- 

 paratively were to take place, and then for one or 

 two years a great number, the effect would be a 

 small proportion of births to marriages in the 

 registers. This was strikingly illustrated in the 

 table for Prussia and Lithuania, and would be 

 confirmed by an inspection of all the other tables 

 collected by Sussmilch ; in which it appears that 

 the extreme proportions of births to marriages are 

 generally more affected by the number of mar- 

 riages than the number of births, and consequently 

 arise more from the variations in the disposition 

 or encouragement to matrimony, than from the 

 variations in the prolifickness of marriages. 



The common epidemical years which are inter- 

 spersed throughout these tables, will not of course 

 have the same effects on the marriages and births 

 as the great plague in the table for Prussia ; but 

 in proportion to their magnitude, their operation 

 will in general be found to be similar. From the 

 registers of many other countries, and particularly 

 of towns, it appears that the visitations of the 

 plague were frequent at the latter end of the 17th, 

 and the beginning of the 18th centuries. 



In contemplating the plagues and sickly seasons 

 which occur in these tables after a period of rapid 

 increase, it is impossible not to be impressed with 

 the idea, that the number of inhabitants had in 



