Charles Babbage - The Difference Engine Limitations

The Difference Engine was impressive, but Babbage saw that it had real limitations in two respects:

1. Like most machines, the Difference Engine was engineered to mechanize a very specific kind of work. Washing machines mechanize one kind of human labor, whereas a steam shovel performs a very different kind of work, and the two machines are not interchangeable. Similarly, the Difference Engine was useful for performing only one kind of calculation at a time. When one wished to use the Difference Engine for one of the other kinds of calculation of which it was capable, this meant reconfiguring the structure of the machine itself.
   
2. There were, of course, many kinds of calculation that the Difference Engine was not even capable of at all: for such calculations, it would be necessary to build an entirely different machine.