Electrical measuring instruments : grand prize Louisiana Purchase Exposition, St. Louis, 1904 (1904)
Leeds and Northrup Company · leaf 36
the potential differ-ence between P and Q is then the same as that between A and B. Thisis proportional to the distance PQ, and is positive on one side and nega-tive on the other side of Q. The distances PQ could, therefore, be usedas ordinates, and the corresponding positions of the contact brush… … to make up ihc curves of these quantities, the instrument is so arrangedthat as soon as any instantaneous value (tf the current or voltage hasbeen balanced against the potentiometer coil its value is immediatelyprinted on a sheet <>f cross-section paper mounted on a cylinder the axisof which…
![An illustration from [Graphophone patents] (1878)](https://img.insideoutlibrary.com/img/200/ia-graphophonepaten02unit-416-188.webp)
![An illustration from [Graphophone patents] (1878)](https://img.insideoutlibrary.com/img/200/ia-graphophonepaten10unit-289-213.webp)