Instrument for facilitating the calculation of equivalent values

A calculating instrument for converting a numeral representing a given quantity in one unit into a numeral representing the same quantity in a different unit, comprising plate means carrying at least one scale of graduations representing different units of a given quantity, with said graduations being situated at a given distance one from the next along said scale, so that the latter scale is stationary with respect to said plate means, movable scale means operatively connected with said plate means for movement with respect thereto in a direction parallel to said stationary scale, said movable scale means carrying a series of graduations situated one from the next at the same distance as said graduations of said stationary scale and said graduations of said movable scale means being indicative of different characteristics of a numeral, pointer means operatively connected with said movable scale means for movement therewith and extending between said movable scale means and said stationary scale, said pointer means being situated along the graduations of said movable scale means at a location where a part of a numeral situated on one side of said pointer means has a given relationship with respect to a part of the numeral situated on the other side of said pointer means, said plate means including a means for initially situating a given numeral indicating the magnitude of a quantity whose units are represented by said stationary scale at a position with respect to said stationary scale where said numeral will indicate said quantity in a given unit of said stationary scale, said pointer means being movable together with said movable scale means with respect to the numeral thus situated initially at a given position with respect to said stationary scale to a location where said numeral can be converted into another numeral indicating the same quantity in a different unit of said stationary scale.