The first requirement for sketches insofar as they are there to serve as reminders is "to get it in the best point of view" (p. 62). The picturesque is in this sense perspectival: a little bit to the left or a little bit to the right can make a considerable difference as to how picturesque a scene is, by changing how it is framed, shifting symmetries and asymmetries, or even modifying the lighting and color.
The second requirement is to determine how to transfer the scene, which is on the massive scale of nature, to your paper, which requires a much smaller scale. You may need to divide the scene among more than one sketch, for instance. Gilpin recommends establishing reference points in the scene before. Once you've decided how much of the scene you wish to put to paper, pick a couple of the most important elements of the scene and lightly mark on your paper where they will go. This will allow you to build a framework in your sketch that gets the relative situation of different objects right.
The usual sketching instrument for a quick sketch would in Gilpin's day be a stick of black lead, which would rather easily make a light gray mark. At this level of sketching, your primary interest is to capture characteristic features of the landscape without worrying much about light and shade: "It is enough if you express general shapes; and the relations, which the several intersections of a country bear to each other" (p. 64). Since our primary concern here is memory, we want to get the "leading ideas" quickly; if we wait, the quality of the experience can evaporate, and as we are in the midst of traveling, we will likely forget many of the details that contributed to the picturesque beauty of the scene.
One difficulty with this quick-sketch method is that it flattens any complicated scene by making it difficult to remember relative distance. Thus Gilpin recommends that the picturesque traveler, when faced with a more complicated landscape, put down some notes characterizing, as accurately as possible, the various relations of distance in the sketch. This will allow you, when you have more leisure, to put in the right kind of shading or coloring, or the right kinds of additional lines, to convey the depth of the scene properly.
If our only interest in the sketch is to fix the idea in our memory, we do not have to do much with it. It does not have to be pretty or picturesque itself to do its work, although, of course, that would probably help. Communication of the picturesque scene to others is another matter entirely. A few choice marks on the paper are a good reminder to ourselves, but will hardly recall the scene, or even an approximation to it, to someone who never saw it. We need what Gilpin calls the "adorned sketch" (p. 66), something with composition, light effects, and simple pictorial ornamentation. If something were not at least in principle capable of a sketch of this sort, it would hardly have been suitable for a picturesque sketch in the first place; but it is only when you are trying to communicate the scene, however approximately, to others that you need to get this far.
He recommends that you keep your quick sketches and your adorned sketches distinct. Do not, for instance, try to turn your quick sketch into an adorned sketch. Your quick sketch preserves the idea of the scene for you; this is precisely what you do not want to lose, and if you try to adorn your quick sketch, you may end up muddling your own memory of the scene. Instead, you should start your adorned sketch from scratch, using your quick sketch as a guide.
Once you've started your adorned sketch, the first requirement is to capture the composition of the scene. You already will have done so in your quick sketch, but Gilpin suggests that you consider whether it can be improved in any way -- in other words, do you need to be more selective, or draw out something a little more fully than it was in the original scene? Gilpin has no problem with the sketch artist improving things a bit; as we've already seen, nature does things on a scale that simply will not completely transfer to the small frame of a piece of paper, no matter how detailed you are, and it will often be the case that parts of a scene are picturesque, while parts, even if they are beautiful parts, may not contribute in any unified way to the picturesque quality of the whole. It's interesting in this light to think of what Gilpin would think of the modern-day camera; one imagines he would not be impressed by it, thinking that, first, it gives an illusion of detail that does not, in fact, capture as much as one might think at first, and that, second, it commits you to what was there rather than letting you draw out the best features from a picturesque point of view. Gilpin doesn't think you should allow yourselve complete freedom, but he thinks that with objects you may need to emphasize things, while with scenes you may need to be subtle; and, moreover, he thinks that you can reorganize the foreground however you please along as you keep "the analogy of the country" (p. 68). If there are too many trees, thin them out; if a tree is in the wrong place, move it; do them both as you will, as long as you keep the general character of the scene that it made it worthy of a picturesque sketch in the first place. What you as a picturesque traveler are interested in is not the scene as such, but the picturesque itself; you therefore study nature to find its picturesque qualities and focus on drawing those out rather than being slave to the scene, which we might say is the aesthetic equivalent of being a pedant.
The most important element of the composition is the foreground, and it is here you must most carefully exercise your discrimination. It will, of course, be on the bottom part of your paper, and it will serve as the natural guide for setting the rest of the sketch in right order. In your quick sketch you did not expend much effort on it. It is probably too high or too low, or not set out quite right. But here you will need to be much more careful about it. Nonetheless, while Gilpin thinks you should exert some care in it, he doesn't think you have to do much to fill it out. You may be doing an adorned sketch, but you aren't doing a full-scale painting; just focus on what is important for giving the general structure and character of the picture right. From the foreground you move out into the rest of your picture, correcting, refining, and improving upon your quicky sketch. And you should continue to exert some care:
No beauty of light, colouring, or execution can atone for the want of composition. It is the foundation of all picturesque beauty. No finery of dress can set off a person, whose figure is awkward and uncouth. (p. 70)
Up to this point, you should have a correct outline of the scene in pencil. Now you can begin inking with a pen or, if you have the skill, painting with a brush. Gilpin recommends the pen in general, with India ink; in an ideal sense painting, as in watercolors, is probably the best, but thinks that it requires considerably more skill to do well. You do not need to do the whole thing -- just do what's required to bring out the most important lines of the picture, add notable textures or shadings, and so forth. Again, it's important to keep in mind that an adorned sketch is not intended to be a landscape portrait, but merely a way of communicating the basic ideas of a picturesque scene to someone who hasn't seen the original. Your goal is not to paint but to finish a sketch with the right touches for conveying these ideas.
In touching up your sketch, expression is a key pont. Gilpin defines expression as "the art of giving each object, that particular touch, whether smooth or rough, which best expresses its form" (p. 72). Even the finest painter cannot really capture all the richness of nature. Some selection of what is most important is necessary even for someone who can make very lifelike paintings; and painters have to use all sorts of tricks of the eye even to get as lifelike as they do, whereas nature does not. In a sketch, it becomes even more important to select out just those features that are most important for contributing to the picturesque beauty of the whole. Excellent expression is really a mark of artistic genius; most people will not be able to achieve the best kinds of expression, at least not consistently. But, again, our primary interest is communication of the picturesque, not fine art. Even slight improvements can go a long way toward making an adorned sketch successful, regardless of your talent.
After the outline you need effects of light and shade, and here Gilpin recommends that even the tyro switch to a brush: a little wash of color with a brush will do much more than you can probably do with a pen. Just a little color to capture the differences in light will do. But we want not to capture just the illumination falling on objects but also the general effect, by drawing out contrasts and variations. You don't need to capture all the light in the scene: just the most important light from the picturesque point of view.
Gilpin suggests that you might consider adding a figure, like a wagon or a person or an animal, but that if you do, you do so sparingly, and only to bring out more clearly something in the sketch -- making it more obvious, for instance, that a set of lines is a road, or breaking an otherwise too monotonous line, or clarifying the distances in your picture. With the figures actually there, though, like trees, it is not necessary to get into details. Unless it is a very striking contributor to the picturesque quality of the scene, it does not matter what it looks like, oak or pine or elm, as long as it looks like a tree, and does not problematize the picture.
Gilpin recommends some light staining of the picture to reduce the glaring contrast between white of paper and black of ink. He also considers the addition of color (in addition to the staining), but recommends very conservative use of it, staring with a very light sense of the color of the horizon (whether it is light blue, rosy pink, etc.). He recommends a layering method: first, tint your entire sketch with the horizon-color you are using, then tint the horizon, and lightly wash the color up into the sky. This will prevent your colors from standing out too harshly, while giving a general sense of the color-difference between sky and scene. And as he puts it in a poem on landscape sketching, the sky gives a general coloring to the whole of a scene; just think of the difference in colors in the whole world between an overcast sky and a sunrise sky. You can then tint the middle ground umber, then go over the soil with a touch of red and vegetation with a touch of green; and then move from there to the foreground, in which you just heighten by a bit of burnt sienna for the soil, perhaps with a touch of blue in the shadows, and a bit of green and burnt sienna for the vegetation. He also gives some tips on clouds. You aren't trying to capture the full colors of the scene, which you cannot in any case do: you are trying to give a hint of how the colors contribute to the harmony and variety of the picturesque whole, and this does not even require getting the colors entirely right, as long as the colors of the sketch are reasonably harmonious among themselves. Harmony of color, not color itself, is the key thing.
You will notice that I keep harping on the point that this is just a sketch. It is an approximation for the purposes of memory and communication, and that is all. As Gilpin says, "General ideas only must be looked for: not the peculiarities of portrait" (p. 87). And this is actually important for Gilpin's notion of picturesque travel. Beautiful painting is something only a master can really attain with consistency. But beautiful sketching is something that can be done even by someone who does not have the time or the resources to put into the development of a full artistic mastery. Sketches are an everyman's sort of art. They do not have to be brilliant. In the case of quick sketches, they just have to be good enough to remind you; and in the case of adorned sketches, they just have to help you communicate the basic picturesque sense of the scene. And, again, as you will recall, one of Gilpin's recommendations for picturesque travel is that it is a rational amusement; it is very important to him that we understand that the kind of sketching required for it is something almost everyone can do. Some will do it much better than others; but everyone can do it well enough for quick sketches, with just a slight bit of practice, and almost everyone can do it well enough for adorned sketches, with just a bit more practice.
Thus sketching. It is notable, though, that Gilpin was most famous not for his sketches but for his descriptions or observations. These were published with sketches, and people did like the sketches, but it was the descriptions that caught imagination. Thus it is important to say something about the other element of communicating picturesque ideas, that found in his several published Observations, which he wrote out descriptions of his own picturesque travels. In the dedication to his Observations on the Scottish Highlands, he calls this picturesque description and notes that it was a relatively new kind of writing. Unfortunately that's about as much as we get from Gilpin on his method of verbal description. But in essence it is perhaps not such a difficult thing. Gilpin's Observations are all travelogues, and were used as travel guides; it's just that their focus is not generally on the history of the places Gilpin went, but on the various features of the scenery. And the vocabulary is that of an art critic, discussing where the picturesque landscapes are, the general way in which they are picturesque, and the way they might be sketched. Nothing beats a taste of Gilpin himself on this point. The following is from his Observations on the River Wye (the consistent use of it's where we would use its is Gilpin's own, as is the double-c for 'echo'):
The Wye takes it's rise near the summit of Plinlimmon; and dividing the counties of Radnor, and Brecknoc, passes through the middle of Herefordshire. From thence becoming a second boundary between Monmouth, and Glocestershire, it falls into the Severn, a little below Chepstow. To this place from Ross, which is a course of near forty miles, it flows in a gentle, uninterrupted stream; and adorns, through it's various reaches, a succession of the most picturesque scenes.
The beauty of these scenes arises chiefly from two circumstances—-the lofty banks of the river, and it's mazy course; both which are accurately observed by the poet, when he describes the Wye, as ecchoing through it's winding bounds. It could not well eccho, unless it's banks were both lofty and winding.
From these two circumstances the views it exhibits, are of the most beautiful kind of perspective; free from the formality of lines.
Every view on a river, thus circumstanced, is composed of four grand parts; the area, which is the river itself; the two side-screens, which are the opposite banks, and mark the perspective; and the front-screen, which points out the winding of the river. (p. 17)
And that's basically Gilpin on the picturesque. However, I think I might do one more post in this series to give some indication of the influence of Gilpin's account; probably focusing on Jane Austen's use of it.