A great deal more might usefully be said with reference to the composition of lines if space would permit, but this general reference may be given as a sort of summing up.
If the disposition of the lines constitutes such a perfectly symmetrical design that it is at once recognised as symmetrical, then it is wrong, because the artifice by which pleasing composition is attained is betrayed, and we feel the thing to be artificial. If, on the other hand, the lines fall so as to make the beholder conscious of their presence, as, for instance, cutting off a portion of the subject or presenting a one-sided appearance, again it is wrong. In neither case should the lines or the objects suggesting them be felt at all until sought for, neither as being very right or very wrong.
In art it is a maxim that the means by which the thing is done should not proclaim itself, and hence it must apply to pictorial photography, which is an effort after the artistic. A composition should please without our quite knowing why, and without our being able to see the machinery, as it were, by which our pleasurable sensations are set in motion.
But whilst it is convenient to speak of lines in the landscape, it is only a manner of speaking, for, as we know very well, photography, unlike pen drawing, has to do with "tones," that is, masses of light and shade. Now the general rules suggested as regards the arrangement of lines, apply in much the same way if we regard a picture (as we should do) as consisting of masses of light and shade.
If when standing before a picture we close the eyes and then suddenly open them, our attention is certain to be drawn to the highest light or the deepest shadow, and hence, as a general rule, whichever of these is the strongest to attract attention, that should be in or near the principal object (indeed it will make of itself the principal object), and should therefore be well removed from the margins of the picture.
Refer back to fig. 8, in which the light patch of sky, the light in the water and the two clusters of light rushes, all form competing points of attraction, and if these are too near the margins, they remind us of those margins, hence the improvement in effect when these are cut away or left out.
But disposing of the highest light and deepest dark does not finish the matter. There is a certain relative degree of lightness and darkness between everything in nature. Moreover, colours have to be interpreted by certain degrees of light and shade according to the distance objects are away from us, and according to the amount of light falling on them.
Such relative lightness and darkness is called "tone." The word used in this sense has nothing to do with "tone" as applied to the colour of a print, which colour we change by a process we call "toning," and upon the correct rendering of relative tones so much of the effect of a picture depends, and so much of its emotional qualities.
Generally speaking, although there are often exceptions, the further an object is from us the grayer it seems. White becomes less white, and dark objects grow less dark, until in the distance both, under ordinary circumstances, come almost to the same "tone," and we see the distance only as a gray hazy mass.
If for a subject we have a figure of a woman by a stream of water and we make an under-exposed negative of it, or develop the negative to too great a density, we shall very likely have a print in which the water and the woman's apron and cap come very much whiter with regard to the rest of the subject than ever they appear in nature, whilst the distance will very likely come too dark. Here we show a disregard for the correct rendering of relative tones and the effect is hard and harsh, unlike nature. We must therefore endeavour, both in exposure and development and printing, to preserve relative tones exactly as they are in nature, and constant study and observation of nature should be carried on in order that the eye may be trained to know how things come relatively in nature, and so be able to decide at a glance if the photograph is good.