DRAWING.

VII.

On the manner of representing portraits.

26. It would certainly be very curious and very useful to be able to represent the faces of men naturally by means of this machine. The task is particularly successful in small scale; and when among the objects thus depicted one finds a person of acquaintance, they are recognized very clearly, even when the full appearance of the person might not occupy half an inch on the paper. However, there are greater difficulties in succeeding on a large scale; because when a head is represented in its natural size, a glass is used, as previously mentioned for prints, and the face is placed at the location where plate F (same No. 25) should be. But the face that then appears quite distinctly enough to recognize the person and satisfy the view, does not have marked enough features to be followed exactly as necessary to maintain resemblance. The reason is that the traits appear vivid and distinct in the camera obscura, when the convergence of rays emanating from the same point of an object, is made exactly on the paper in a single point; but if one point is slightly farther than another from the convex glass (when the distance is as small as needed to represent the objects in their natural size) this so alters the place of this convergence that, for the different parts of the face, these locations differ by more than two and a half inches. Thus, it is not surprising that not all the features are as

Translation Notes

1. "La chambre obscure" refers to a camera obscura, an early device used to project images onto a surface, which may not be familiar to modern audiences.

2. "Verre" is translated as "glass," referring, in this context, to the lens used in the device.