Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. The excellence of the following Treatise is for well known to all in any tolerable degree conservant with the art of Painting, that it would be almost superfluous to say any thing respecting it, were it not that it here appears under the form of a new translation, of which some account may be expected.