584 



KNOWLEDGE ♦ 



[May IJ, 1862. 



M 



THE COMET. 



TE continue the patli of the comet Wells to the end 

 of next week. 



POPULATION OF THE EARTH. 



By the Editor. 



SEVERAL corresjiondents ask whether a computation, 

 such as that made in letter 391, p. 57.5 might not be 

 based on conditions more in accordance with known facts. 

 I suggest the following : — From the Registrar-General's 

 return just presented to Parliament, it appears that for 

 an estimated population of rather more than 26 millions 

 in England, the deaths were, 491,813 ; the births, 

 883,.508— an increase of 391,69.5,— say 390,000 for 

 26,000,000 (the real increase slightly greater). This is at 

 the rate of 39 for 2,600, or 3 for 200— that is U per cent. 

 Suppose now that ."),000 years ago the human popidation 

 of the globe were one million (which, considering that 

 according to every Egyptologist of standing, the Pyramids 

 were built long before that time, and that 30,000 lives were 

 expended in building them, must be considered a very 

 moderate allowance), then, what would be the present 

 population of the globe if there had been an increase of I5 

 per cent per annum during the last 5,000 years? 



The problem thus presented is very simple. The rate of 

 increase per annum is from 1,000 to 1,015, so that we have 

 merely to multiply one million (or whatever the population 



was 5,000 years ago) by — _ five thousand times. Without 



logarithms this would be rather a difficult task ; but with 

 the aid of logarithms (see our papers on that subject) it is 

 sufticiently easy : — 



^"^^ (i-ooo)"^°8-^'oi5)-i«g-aooo) 



= 3-0064660 - 3 

 = 0-0064660 



Multiplying by 5000 we get, 



log. (101^ 



BOOO 



= 32-330000 



Viooo/ 



log. 1,000 noo = 6 



log. (earth's population under the assumed 



conditions) = 38-33000OJ 



Whence the earth's present population would be 



2 1 3,800,000,000,000,000,000,000,000,000,000,000,000 



{t\ being only one million 5,000 years ago, it had increased 

 during the last 5,000 years at the same rate that the popu- 

 lation of England has increased during the last year. If, 

 5,000 years ago, the population of the earth had been but 

 10, we should have to strike five digits from the above. 



But, to show how very far the conditions attained in a 

 civilised country are from those under which life could 

 possibly exist for any length of time (as science measures 

 time) on the earth as a whole, let us suppose that only 

 4,000 years ago (and even the believers in the Great 

 Pyramid as a stone Bible will allow so much), the earth's 

 population did not exceed 10. Then we have, to determine 

 the earth's present population, this calculation : — 



1000 

 log. ( till ) = 25-864000 



/loisV 

 Viooo/ 



= 1 



log. 10 



log. (earth's population under the 



assumed conditions) ... ... = 26-864000 



whence the earth's present population would be 

 731,140,000,000,000,000,000,000,000. 

 Now we have seen that with ten persons to the square 

 yard (rather close crowding) there would be 30,000,000 to 

 the square mile, and to the entire surface of the_earth 

 (land, water, and ice) 200,000,000 times as many, or 



6,000,000,000,000,000. 

 Wherefore, even at the rate of increase which has taken 

 place in this much maligned old country during the past 

 year (of course the " good old times " were ever so much 

 better), the earth's population, beginning with only 10, 



