90 Progress of Population and Wealth 



From 1810 to 1820, the increase was . . 34.3 per cent- 

 Deduct the number immigrating, 132,400, .equal to 2.2 



32.1 " 



From 1820 to 1830, the increase was . . 33.8 

 Deduct the number immigrating, 231,000, equal to 2.9 



30.9 " 



From 1830 to 1840, the increase was . . 34.7 

 Deduct the number immigrating, 540,000, equal to 5.1 



29.6 " 



According to which computation the actual and natural increase, 

 in each decennial term, may be thus compared : 



Per cent. Per cent. Per cent. Per cent. Per cent. 



Actual increase, 35.7 36.2 34.3 33.8 34.7 



Natural increase, 33.9 33.1 32.1 30.9 29.6 



Thus showing, in the rate of decennial natural increase, a dimii 

 nution of 4.3 per cent during forty years, or an average of about 1 

 per cent for each term of ten years. 



It will be perceived that this diminution of ratio is not uniform, 

 but that it increases progressively, and with a regularity which is 

 remarkable, and which gives some assurance that the estimates 

 made of the numbers acquired by immigration are not wide of the 

 truth. The differences of ratio are in the following series : 8, 10, 

 12, 13. 



Let us now see how far this decline in the rate of natural in- 

 crease derives confirmation from the census itself. If there be 

 such a diminution of ratio, it will be manifested by the decreasing 

 proportion of children under ten years of age, since, at each census, 

 they constitute all of the population who have been born since the 

 preceding census. 



From 1800 to 1840, the number of white females and of children 

 under ten, and their proportions to each other, were as follows : 

 1800. 1810. 1820. 1830. 1840. 



No. of females, 2,100,068 2,874,433 3,871,647 5,171,115 6,939,842 



No. of children under 10, 1,489,315 2,016,479 2,625,790 3,427,730 4,485,130 



Prop, of children, per cent,. . . 70.92 70.15 67.82 66.20 64.63 



1810 is probably too low. Dr. Seybert, on whose authority I have stated the immigra- 

 tion from 1790 to 1810 at only 120,000, estimates the whole gain from immigrants and 

 their increase at 180,000 ; whereas, the estimate made in the preceding chapter would 

 not reckon it at more than 160,000, viz. : 58,000+82,000-}-the increase of 58,000 for 10 

 years, which could not exceed 20,000. He has thus, probably, more than corrected the 

 error of underrating the number of immigrants by too high an estimate of their increase. 



