This extraordinary man was born in 1705, at Elmeton, in Derbyshire. His father was a schoolmaster; and yet, from some strange neglect, Jedediah was never taught either to read or write. So great, however, were his natural talents for calculation, that he became remarkable for his knowledge of the relative proportions of numbers, their powers and progressive denominations. To these objects he applied all the powers of his mind, and his attention was so constantly rivetted upon them, that he was often totally abstracted from external objects. Even when he did notice them, it was only with respect to their numbers. If any space of time happened to be mentioned before him, he would presently inform the company[Pg 68] that it contained so many minutes; and if any distance, he would assign the number of hair-breadths in it, even though no question were asked him.

Being, on one occasion, required to multiply 456 by 378, he gave the product by mental arithmetic, as soon as a person in company had completed it in the common way. Being requested to work it audibly, that his method might be known, he first multiplied 456 by 5, which produced 2,280; this he again multiplied by 20, and found the product 45,600, which was the multiplicand, multiplied by 100. This product he again multiplied by 3, which gave 136,800, the product of the multiplicand by 300. It remained, therefore, to multiply this by 78, which he effected by multiplying 2,280, or the product of the multiplicand, multiplied by 5, by 15, as 5 times 15 is 75. This product being 34,200, he added to 136,800, which gave 171,000, being the amount of 375 times 456. To complete his operation, therefore, he multiplied 456 by 3, which produced 1,368, and this being added to 171,000, yielded 172,368, as the product of 456 multiplied by 378.

From these particulars, it appears that Jedediah\'s method of calculation was entirely his own, and that he was so little acquainted with the common rules of arithmetic, as to multiply first by 5, and the product by 20, to find the amount when multiplied by 100, which the addition of two ciphers to the multiplicand would have given at once.

A person who had heard of these efforts of memory, once meeting with him accidentally, proposed the following question, in order to try his calculating[Pg 69] powers. If a field be 423 yards long, and 383 broad, what is the area? After the figures were read to him distinctly, he gave the true product, 162,009 yards, in the space of two minutes; for the proposer observed by the watch, how long it took him. The same person asked how many acres the said field measured; and in eleven minutes, he replied, 33 acres, 1 rood, 35 perches, 20 yards and a quarter. He was then asked how many barley-corns would reach eight miles. In a minute and a half, he answered 1,520,640. The next question was: supposing the distance ............