It could therefore factorize numbers with less than 13 decimal figures in around 18 minutes, a task which would take several days by hand. D. H. Lehmer, generally recognized as the inventor of the first sieve, began building his automatic sieve in 1926 and only heard about the Carissan machine for the first time in 1989. Lehmer's sieve, which in many respects was less sophisticated than the Carissans' system, used bicycle chains driven by an electric motor. It was the first in a long line of prototypes. Although sieves seem to have gone out of fashion and have been outclassed by modern computers, the methods they used remained the most powerful available for factoring integers until 1970.
Electronic sieves are still faster than software programmes.
For example, a sieve can perform up to 2 x 1012 trials per second, compared to 2 x 106 on a workstation. In spite of this, modern sieves are no longer used for factoring integers. An approach based on more sophisticated mathematical tools and massive distribution of programmes on workstations is more powerful.