Certain other inventors have applied the same principle in a different way.
Within a few years several methods had been proposed by different inventors, but none was at first very successful, not from any fault in the principle, but because the effect of electrostatic capacity of the line was left out of account in the early arrangements.
Utilizing this principle many inventors have devised forms of electrostatic voltmeter.
More modern inventors have therefore adopted the plan of drawing the glass direct from the furnace.
The mariner's compass during the early part of the 19th century was still a very imperfect instrument, although numerous inventors had tried to improve it.