Null type multirange measuring system which maintains constant sensitivity throughout the several ranges

Claim 1

A MEASURING SYSTEM COMPRISING A DETECTOR-AMPLIFIER, AN ATTENUATING SLIDEWIRE FOR SAID DETECTOR-AMPLIFIER INCLUDING A CONTACT, A RESISTOR IN SERIES WITH SAID CONTACT OF SAID ATTENUATING SLIDEWIRE, SAID ATTENUATING SLIDEWIRE HAVING TWO LEG CONNECTIONS EACH INCLUDING EQUAL-VALUED RESISTORS, ONE OF THEM BEING CONNECTED ACROSS AN INPUT CIRCUIT OF SAID DETECTOR-AMPLIFIER FOR APPLYING TO IT A SELECTED FRACTION OF AN ERROR SIGNAL, AN ADJUSTABLE CURRENT SHUNT COMPRISING A SHUNTING SLIDEWIRE HAVING TWO LEG CONNECTIONS, ONE INCLUDING A RESISTOR AND THE OTHER INCLUDING A MEASURING SLIDEWIRE, THE RESISTANCE OF SAID FIRST-MENTIONED LEG CONNECTION BEING EQUAL TO THE EQUIVALENT RESISTANCE OF THE OTHER SAID LEG CONNECTION FOR PROVIDING A MAXIMUM RATIO OF THE CHANGE IN VOLTAGE ACROSS SAID MEASURING SLIDEWIRE EQUAL TO THE SUM OF THE RESISTANCE OF SAID SHUNTING SLIDEWIRE PLUS THE EQUIVALENT RESISTANCE OF ONE OF SAID LEG CONNECTIONS DIVIDED BY SAID LAST-MENTIONED RESISTANCE, A SOURCE OF CURRENT, A RESISTOR IN SERIES THEREWITH, CONNECTIONS FOR CONNECTING SAID SOURCE OF CURRENT AND SAID SERIES RESISTOR IN SERIES-CIRCUIT RELATION WITH SAID ADJUSTABLE CONTACT OF SAID SHUNTING SLIDEWIRE AND THE JUNCTURE OF ITS LEG CONNECTIONS, ADJUSTMENT OF SAID SHUNTING SLIDEWIRE VARYING THE CURRENT THROUGH SAID MEASURING SLIDEWIRE, AN INPUT CIRCUIT FOR APPLICATION THERETO OF A VOLTAGE, THE MAGNITUDE OF WHICH IS TO BE MEASURED, INCLUDING A CONNECTION TO SAID MEASURING SLIDEWIRE AND TO SAID ATTENUATING SLIDEWIRE BY WAY OF SAID RESISTOR CONNECTED IN SERIES WITH THE CONTACT OF SAID ATTENUATING SLIDEWIRE, THE DIFFERENCE BETWEEN SAID VOLTAGE THE MAGNITUDE OF WHICH IS TO BE MEASURED AND THAT FROM SAID MEASURING SLIDEWIRE PRODUCING AN ERROR VOLTAGE, A FRACTIONAL PART OF WHICH IS APPLIED TO SAID DETECTOR-AMPLIFIER BY SAID EQUAL-VALUED RESISTOR CONNECTED ACROSS THE INPUT CIRCUIT OF SAID DETECTORAMPLIFIER, AND MECHANICAL MEANS FOR ADJUSTING SAID SHUNTING SLIDEWIRE TO VARY THE CURRENT THROUGH SAID MEASURING SLIDEWIRE AND CONCURRENTLY ADJUSTING SAID ATTENUATING SLIDEWIRE TO MAINTAIN SUBSTANTIALLY CONSTANT SAID FRACTION OF SAID ERROR SIGNAL APPLIED TO SAID DETECTOR-AMPLIFIER INDEPENDENTLY OF THE LEVEL OF CURRENT FLOWING THROUGH SAID MEASURING SLIDEWIRE.