Should one need a great many calculations to crunch many numbers, a full-sized Difference Engine is always useful. Should one need to crunch difficult-to-open nuts, this size Engine also comes in handy. Note the convenient dial on the front, to measure the steam pressure on the unit.
Of course, having the Engine is not always enough. Sometimes, one wants to communicate with other Engines out there in the world. For those occasions, one needs a connected telecommunications device: