The simplest application of this method is the printing of a cloud into a landscape from a different negative. Though it is far preferable to obtain the clouds on the same negative, and this is quite easy in ortho-chromatic photography, it is, if you use great judgment, admissible to print in clouds from a separate negative, but this requires an intimate knowledge of out-door effects, and the clouds must be taken in a particular way. Printing in clouds is admissible because, if well done, a truer impression of the scene is rendered. But the ordinary way of taking cloud negatives is much to be condemned. The practice is to point the camera to the zenith if need be, to focus sharply, to to use the smallest stop, develop and select for final use according to the lighting, indeed, not always being very particular on that point. But, by elevating the camera a point of sight is taken different from that employed in taking the landscape; by focussing sharply, often using a lens drawing falsely, the clouds are rendered false in tone and false in drawing. All this an artist detects in a moment, a craftsman, never. The first necessity, then, in taking cloud negatives is that the point of sight shall be the same as that chosen for the landscapes; the second that the clouds shall be so focussed and developed that their tonality shall remain true; and the third and most important point, that the cloud form shall be harmonious with the landscape. The very simplest truths of nature are daily ignored by photographers in the works they exhibit. There are often three, or even four suns in one landscape, or at least the evidence of them; mighty cumuli float over lakes where there is no ripple, and yet there is no reflection; or, as we have seen, reflections of clouds have been printed in where there are ripple marks; or heavy nimbi lighted from one direction are placed over cirro-cumuli lighted from another direction; or, again, a setting sun sinks to rest over wave-broken water that reflects glints of light from exactly the opposite direction.