When a "sitter" is photographed standing in front of a pictorial background, the photograph will represent him either standing in a natural scene, or before a badly-painted picture. Nobody should wittingly punish his sitter by doing the latter when he could do the former, and the first step to form the desirable illusion is pictorial truth. There is no reason why the backgrounds should not be painted truthfully and according to correct principles, for the one is as easy as the other. I daresay the reason is that artists have not intentionally done wrong--it would be too bad to suppose that--but they have treated the backgrounds as independent pictures, and it is for photographers to make what use of them they think proper. The real principles are, however, now stated, by which they can be painted so as to be more photographically useful, and artists and photographers have alike the key to pictorial truth. In conclusion, I would suggest to photographers the necessity of studying nature more carefully--to observe her in their walks abroad, to notice the gradual decrease of objects both in size and distinctness, to remember that their lens is to their camera what their eye is to themselves, to give as faithful a transcript of nature as they possibly can, to watch the flow of nature's lines, as well as natural light and shade, and, by a constant study and exhibition of truth and beauty in their works, make photography eventually the teacher of art, instead of art, as is now the case, being the reviler of photography. PERSPECTIVE. _To the Editors._ Gentlemen,--At the end of Mr. Alfred H. Wall's reply to Mr. Carey Lea's letter on _Artists and Photographers_, I notice that he cautions your readers not to receive the very simple rules of perspective laid down in my paper, entitled _Errors in Pictorial Backgrounds_, until they have acquired more information on the subject. Allow me to state that all I said on perspective in that paper only went to show that there should be but one horizon in the same picture; that the lines of all objects _below_ that horizon should run up to it; that the lines of all objects _above_ should run down, no matter where that _one_ horizon was placed; and that the horizon of the landscape background should be in due relation to the sitter and on a level with the eye of the observer, the observer being either the lens or the painter. If your correspondent considers that I was in error by laying down such plain and common sense rules, which everyone can see and judge for himself by looking down a street, then I freely admit that your correspondent knows a great deal more about _false_ perspective than I do, or should like to do.