CH. XIIl] CALCULATING PRODIGIES 273 



Here are some typical questions put to and answered by 

 him in his exhibitions during the years 1815 to 1819 — they are 

 taken from authenticated lists which comprise some hundreds 

 of such problems : few, if any, are inherently difficult. His 

 rapidity of work was remarkable, but the time limits given 

 were taken by unskilled observers and can be regarded as only 

 approximately correct. Of course all the calculations were 

 mental without the aid of books, pencil, or paper. In 1815, 

 being then nine years old, he was asked : — If the moon be distant 

 from the earth 123,256 miles, and sound travels at the rate of 



4 miles a minute, how long would it be before the inhabitants 

 of the moon could hear of the battle of Waterloo : answer, 

 21 days, 9 hours, 34 minutes, given in less than one minute. 

 In 1816, being then ten years old, just learning to write, but 

 unable to form figures, he answered questions such as the 

 following: — What is the interest on £11,111 for 11,111 days at 



5 per cent, a year: answer, £16,911. lis., given in one minute. 

 How many hogsheads of cider can be made from a million of 

 apples, if 30 apples make one quart : answer, 132 hogsheads, 

 17 gallons, 1 quart, and 10 apples over, given in 35 seconds. If 

 a coach-wheel is 5 feet 10 inches in circumference, how many 

 times will it revolve in running 800,000,000 miles: answer, 

 724,114,285,704 times and 20 inches remaining, given in 50 

 seconds. What is the square root of 119,550,669,121 : answer 

 345,761, given in 30 seconds. In 1817, being then eleven 

 years old, he was asked: — How long would it take to fill a 

 reservoir whose volume is one cubic mile if there flowed into 

 it from a river 120 gallons of water a minute : answered in 

 2 minutes. Assuming that light travels from the sun to the 

 earth in 8 minutes, and that the sun is 98,000,000 miles off, if 

 light takes 6 years 4 months travelling from the nearest fixed 

 star to the earth, what is the distance of that star, reckoning 

 365 days 6 hours to each year and 28 days to each month — 

 asked by Sir William Herschel: answer, 40,633,740,000,000 

 miles. In 1818, at one of his performances, he was asked: — If the 

 pendulum of a clock vibrates the distance of 9f inches in a second 

 of time, how many inches will it vibrate in 7 years 14 days 



b. e. 18 



