Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III CAMERAS, LENSES, AND SHUTTERS In a letter written to his brother, in 1816, Niepce describes how he secured what was probably the first picture ever made with a camera. He says: " My object glass being broken, and being no longer able to use my camera, I made an artificial eye with Isidore's ring box, a little thing from sixteen to eighteen lines square. ... I placed this little apparatus in my workroom, facing the open window, looking on to the pigeon house. I made the experiment in the way you are acquainted with, and I saw on the white paper the whole of the pigeon house seen from the window." This tells, in a few words, the basic principles of a camera; for it is, in fact, nothing but a light- tight box so arranged that, only when the image is to be projected, a few rays may be admitted through one end, and they form the image of whatever object or objects we may be photographing, on the ground glass at the other end. The very name "camera" means only a chamber or compartment. The principles of the projecting of images of objects by means of light rays were known, however, a long time before the camera was invented. About the middle of the sixteenth century an Italian by the name of Baptista Porta invented the " camera obscura," which, as its name implies, was nothing more or less than a darkened room to which light was admitted only through a single small hole in the window shutter. We can any one of us easily repeat his experiments by tightly closing the windows of a room with dark shades and through one shade cutting a small hole. On the wall opposite this window hang a sheet, and, when the sun is shining, we can see a faint, inverted image on the sheet of whatever the window may look out upon. It is inverted because the rays of light emanating from t...