Proportion to the revenue? This is most likely a flat consumption tax. Income taxes did not exist in 1776.

Adam Smith also outlined four canons of taxation, which serve as guiding principles for a fair and effective taxation system:

The Tax Should be Certain: Tax laws and rates should be clear and stable. The Tax Should be Convenient: Taxation should be easy and convenient for taxpayers. The Tax Should be Easy to Assess: Taxation should be straightforward and simple to calculate. The Tax Should be Light: Taxation should be minimal and not excessively burdensome.