And should a thief afterwards purloin the treasures—if the mute testimony of the picture were to be produced against him in court—it would certainly be evidence of a novel kind; but what the judge and jury might say to it, is a matter which I leave to the speculation of those who possess legal acumen.
The articles represented on this plate are numerous: but, however numerous the objects—however complicated the arrangement—the Camera depicts them all at once. It may be said to make a picture of whatever it sees. The object glass is the eye of the instrument—the sensitive paper may be compared to the retina. And, the eye should not have too large a pupil: that is to say, the glass should be diminished by placing a screen or diaphragm before it, having a small circular hole, through which alone the rays of light may pass. When the eye of the instrument is made to look at the objects through this contracted aperture, the resulting image is much more sharp and correct. But it takes a longer time to impress itself upon the paper, because, in proportion as the aperture is contracted, fewer rays enter the instrument from the surrounding objects, and consequently fewer fall upon each part of the paper.
PLATE IV. ARTICLES OF GLASS.
PLATE IV. ARTICLES OF GLASS.
The photogenic images of glass articles impress the sensitive paper with a very peculiar touch, which is quite different from that of the China in Plate III. And it may be remarked that white china and glass do not succeed well when represented together, because the picture of the china, from its superior brightness, is completed before that of the glass is well begun. But coloured china may be introduced along with glass in the same picture, provided the colour is not a pure blue: since blue objects affect the sensitive paper almost as rapidly as white ones do. On the contrary, green rays act very feebly—an inconvenient circumstance, whenever green trees are to be represented in the same picture with buildings of a light hue, or with any other light coloured objects.