Apparatus manufactured grew from telegraph apparatus to include : marine and mine signalling apparatus, measuring and scientific instruments, wireless telegraphy, telephone exchanges ( manual and automatic ) and apparatus, wet and dry batteries, landlines, ebonite, cable accessories and joint boxes
22.
As a result, many examples have been put on the air, although practical operation is hampered by the necessity of building new, custom power supplies ( the original dry batteries, which supplied + 1.5, + 4.5, + 45 and + 90 volt outputs, being unobtainable or display pieces only ) and the limited output power and range.
