The Martian Technology Report states:
"Down on the left a busy little digging mechanism had come into view, emitting jets of green vapour and working its way round the pit, excavating and embanking in a methodical and discriminating manner. This it was which had caused the regular beating noise, and the rhythmic shocks that had kept our ruinous refuge quivering. It piped and whistled as it worked. So far as I could see, the thing was without a directing Martian at all."
It is worth noting that the Martians made extensive use of mechanisms whose actions were completely autonomous from direct control. The machines, of which the described Digging Machine is one example, are for the most part substantially smaller than the machines operated by Martian controllers, with few specimens exceeding ten feet in any dimension. These devices too moved about on articulated legs, normally five or more. Human scientists have managed to restore a couple of these devices to a functional state. However, attempts to actually control them have had less luck - one device had to be forcibly deactivated when it started excavating the workshop in which it was being tested.
For the most part the machines only perform a single task, like excavating a pit, or assembling some of the smaller machinery. However, they seem to possess a sort of rudimentary intelligence, unlike terrestrial automata like player pianos or other such devices. The machines do not merely perform the same action over and over again, but are able to vary their behaviour according to the situation - for example, the Assembling Machine is able to determine which components it requires to build the ordered machine, and to go looking for those components, despite the fact that they may be scattered in various parts of the Martians' pit, or concealed beneath a pile of other items. Similarly the Digging Machine is able to determine which sections of the pit to dig, which are unstable and need to be reinforced, and which areas are already in the desired state.
The actions of the machines seem to be controlled by a complex arrangement of crystalline wafers. These wafers have extremely detailed patterns etched into them, generally only visible with the aid of a powerful microscope. These patterns appear to be designed to channel electricity in a way which allows the machines to operate independently of outside direction. The patterns of these wafers, and their properties, are being vigourously investigated. It is believed that further development of this technology will be of immense aid in the future development of automated machines.