272 CALCULATING PRODIGIES [CH. XIII 



His reputation increased and, before he was nine years old, 

 his father found it profitable to take him about the country 

 to exhibit his powers. A couple of distinguished Cambridge 

 graduates (Thomas Jephson, then tutor of St John's, and 

 John Herschel) saw him in 1817, and were so impressed by 

 his general intelligence that they raised a fund for his educa- 

 tion, and induced his father to give up the rdle of showman ; 

 but after a few months Bidder senior repented of his abandon- 

 ment of money so easily earned, insisted on his son's return, 

 and began again to make an exhibition of the boy's powers. 

 In 1818, in the course of a tour young Bidder was pitted 

 against Colburn and on the whole proved the abler calculator. 

 Finally the father and son came to Edinburgh, where some 

 members of that University intervened and persuaded his 

 father to leave the lad in their care to be educated. Bidder 

 remained with them, and in due course graduated at Edinburgh, 

 shortly afterwards entering the profession of civil engineering 

 in which he rose to high distinction. He died in 1878. 



With practice Bidder's powers steadily developed. His 

 earlier performances seem to have been of the same type as 

 those of Buxton and Colburn which have been already 

 described. In addition to answering questions on products of 

 numbers and the number of specified units in given quantities, 

 he was, after 1819, ready in finding square roots, cube roots, 

 &c. of high numbers, it being assumed that the root is an 

 integer, and later explained his method which is easy of appli- 

 cation: this method is the same as that used by Colburn. By 

 this time he was able also to give immediate solutions of easy 

 problems on compound interest and annuities which seemed to 

 his contemporaries the most astonishing of all his feats. In 

 factorizing numbers he was less successful than Colburn and 

 was generally unable to deal at sight with numbers higher than 

 10,000. As in the case of Colburn, attempts to be witty at 

 his expense were often made, but he could hold his own. Asked 

 at one of his performances in London in 1818, how many bulls' 

 tails were wanted to reach to the moon, he immediately 

 answered one, if it is long enough. 



