I send you the two essays I mentioned. As the standing or not standing of such an Arch is not governed by opinions, therefore opinions one way or other will not alter the fact. The opinion of its standing will not make it stand, the opinion of its falling will not make it fall, but I shall be exceedingly obliged to you to bestow a few thoughts on the subject and to communicate to me any difficulties or doubtfulness that may occur to you because it will be of use to me to know them.

As you have not the Model to look at I enclose a sketch of a Rib, except that the blocks which separate the Bars are not represented. I am Dear Sir Your Obliged friend and Humble servant