The dominant arena for the technology-based lessons learned is the human- machine interface. It is the most critical aspect of an interactive robot: all of the operator's actions and perceptions are channeled through this one gateway. The second area is the robot-environment interface, since all the robot's capabilities. 19 Apr Dewar developed structural formulas for benzene (), did research in spectroscopy for more than 25 years, and by had constructed a machine for producing liquid oxygen in quantity. About he conceived the idea of using vacuum-jacketed vessels for the storage of low-temperature liquid. Harry led them to an Avery weighing machine placed next to the station entrance. He asked Devar to stand on the weighing bench of the vending type weighing machine and inserted a one pice coin into its slot. The machine started to whirr, its coloured psychedelic lights came on, rotated and it soon vended out a ticket with.