Figure 83 is a photograph of an antique piece of equipment. It is made of wood and has scroll decoration reminiscent of a mantelpiece clock. Its appearance is dominated by a central framed diamond-shaped sheet made of polished metal. There is a diamond shaped grid layout etched onto the sheet with letters etched at the intersections of the lines. Starting at the top, the top row comprises a single letter 'A'. The second row is 'B' and 'D'. The third row is 'E' and 'F' and 'G'. The fourth row is 'H', 'I', 'K' and 'L'. The fifth row is the central row and its five intersections do not have letter labels. The sixth row is 'M', 'N', 'O' and 'P'. The seventh row is 'R', 'S' and 'T'. The eighth row is 'V' and 'W'. The final ninth row at the bottom of the diamond grid is just 'Y'. Attached to the surface of the diamond sheet above the central row of intersections there is a horizontal brass bar with five pivoted double-ended metal pointers. These are arranged at intersections of scribed lines with the letters at their intersections. It can be deduced that any two pointers, when tilted to the left or right, can indicate a single letter at the intersection of the scribe lines along which they are pointing, thus allowing messages to be transmitted by the appropriate sequential energizing of telegraph wires connected to each pointer. A keyboard can be seen at the base of the machine.

 5.3 An inventive step – a 'battery' of cells