We have seen how the rapidity of a lens is determined; beyond, then, the comparing the relative rapidities of lenses, all tables of exposures are fallacious and unscientific. Can absurdity go any further than some of the data of some of these so-called scientific tables: "Panoramic View," "Living objects out of doors," etc.? Briefly, what is the difference of exposure required on a living ass and on a dead donkey, both out of doors? But seriously, let the student be not led away by such chimeras, for there can be no tables of exposures until the science of meteorology is as fixed a science as mathematics; and any attempt to work by exposure tables will end in dismal failure. If our word is not sufficient to convince any reader, let him note what two eminent scientists think of these tables. Dr. Yogel says, in one of his works, "There is no rule which determines the length of time a photograph has to be exposed to the light;" and Captain Abney has told us he considers such tables absurd and unscientific. It is with his sanction that we quote him on the subject. Exposure must be judged by circumstances: no artificial aids will help. Fortunately for us, plates allow of considerable latitude of exposure.

But as in all good things, simplicity goes hand in hand with perfection. We have advocated quick exposures as absolutely essential to artistic work, and it follows, therefore, that in making quick exposures there is less liability of going wrong; so the two work hand in hand. He who exposes slowly misses the very essence of nature, and it is this very power of exposing so quickly that gives us a great advantage over all other arts. The painter has to resort to all sorts of devices to secure an effect, which perhaps only lasts for half an hour in the day. Not so with photographers, if we see and desire to perpetuate an effect, it is ours in the twinkling of an eye, and thus in a really first-rate photography there will always be a freshness and naturalism never attainable in any other art. And here we would state definitely that the impression of these quick exposures should be as seen by the eye, for nothing1 is more inartistic than some positions of a galloping horse, such as are never seen by the eye but yet exist in reality, and have been recorded by Mr. Muybridge. Here, then, comes in the artist, he knows what to record and what to pass over, while the craftsman, full of himself and his dexterity, tries to take a train going at sixty miles an hour, and lo! it is standing still, or he expends his energy in taking a yacht bowling along abeam because that result is more difficult to obtain than to take it going away from him, and he calls it natural and therefore artistic. Of course such performances are born of ignorance and vanity. Hundreds of such things have been done in the past, hundreds will be done in the future, and they will sell, but only to be finally destroyed. No photographer has yet done a series of marine pictures; here and there one sea-picture has been done which has oftener been the result of chance than of art. As for the ordinary photographs of yachts, they are mere statements of facts that merit no artistic consideration.

Here, then, we must leave the question of exposure. It is, perhaps, the most important and the most difficult of all photographic acts. In the studio the matter is simpler than out of doors, because the light is not so much affected by reflections and various meteorological conditions; in landscape work, on the other hand, exposure becomes a most difficult problem, yet long experience can bring an intelligent man to give comparatively correct exposures, so that the resulting picture may be developed to obtain the exact impression that he requires, still, even after years of experience, he will at times find himself baffled and humiliated by failure.

It is in exposures that intuition acts as it does in all intellectual matters, and he who can seize on the right exposure at once by instinct is the photographer born, and unless, after some practice, the student can do this, there is little hope that his work will ever rise above mediocrity.