The seller lodged this description. It throws a considerable spark from 2 dry cells, the gap being either heavy copper wire mounted in the binding posts atop the coil as shown, or running leads off to a separate spark gap. On the left side of the coil is the adjustable vibrator, and on the right side, a current-reversing switch and 2 binding posts. The glass end slabs are cemented to the coil with hard red sealing wax. With the possible exception of the two binding posts on the right, every part on this device appears to have been hand-machined specifically for it.
Nothing appears mass-produced.
There is a box inside the base with contacts on top that meet spring leaf contacts in the base itself. This is a glass plate condensor, It is not the original, but it is correct size and fully functional. Weight is 28 pounds. Nel 1851, H. D. Ruhmkorff , meccanico ed elettrotecnico tedesco, penso' di produrre correnti indotte in un rocchetto di grandi dimensioni dotato di due avvolgimenti separati Questa invenzione che porta il suo nome ebbe moltissime applicazioni pratiche in quanto rese disponibile una sorgente di alta tensione piu' comoda e potente delle macchine elettrostatiche in uso prima di allora.