Section 1. SALARIES IN CERTAIN COUNTIES. In counties having a population of not less than twenty-one thousand, eight hundred and sixteen (21,816) and not more than twenty-one thousand, eight hundred and twenty-six (21,826); in all counties having a population of not less than forty-one thousand (41,000) and not more than forty-two thousand (42,000); in counties having a population of not less than thirteen thousand, three hundred and eighty-five (13,385) and not more than thirteen thousand, three hundred and ninety-five (13,395); in counties having a population of not less than nineteen thousand, eight hundred and forty-three (19,843) and not more than nineteen thousand, eight hundred and fifty-three (19,853); in counties having a population of not less than thirty-six thousand (36,000) and not more than thirty-six thousand and fifty (36,050); and in counties having a population of not less than twenty-nine thousand, seven hundred (29,700) and not more than twenty-nine thousand, seven hundred and fifty (29,750) according to the last preceding Federal Census, the County Boards of Trustees may make such provisions as they deem necessary for office and traveling expenses of the County Superintendent of Public Instruction; providing that the amount of such expenditures for office and traveling expenses shall not exceed the sum of Six Hundred Dollars ($600) per annum.