Upon every person engaging or continuing within the Town in any service, business or calling not otherwise specifically taxed under this article therein is hereby levied and shall be collected a tax equal to seventy-five one-hundredths of one percent of the gross income of any such business, service or calling. It is specifically provided, however, that salaries, wages or other compensation received for personal services for the government of the United States and directly from the state shall not be included in calculating the gross income of any person under this section.