Page:Micrographia - or some physiological descriptions of minute bodies made by magnifying glasses with observations and inquiries thereupon.djvu/57

Rh waves that appear the brighter, throw towards the eye a multitude of small reflections of light, whereas the darker scarce afford any. The reason of which reflection, the Microscope plainly discovers, as appears by the Figure. In which you may perceive, that the brighter parts of the surface consist of an abundance of large and strong reflections, denoted by a, a, a, a, a, &c. for the surfaces of those threads that run the long way, are by the Mechanical process of watering, creas'd or angled in another kind of posture then they were by the weaving: for by the weaving they are onely bent round the warping threads; but by the watering, they are bent with an angle, or elbow, that is in stead of lying, or being bent round the threads, as in the third Figure, a, a, a, a, a, are about b, b, b (b, b, b representing the ends, as 'twere, of the cross threads, they are bent about) they are creas'd on the top of those threads, with an angle, as in the fourth Figure, and that with all imaginable variety; so that, whereas before they reflected the light onely from one point of the round surface, as about c, c, c, they now when water'd, reflect the beams from more then half the whole surface, as d e, d e, d e, and in other postures they return no reflections at all from those surfaces. Hence in one posture they compose the brighter parts of the waves, in another the darker. And these reflections are also varied, according as the particular parts are variously bent. The reason of which creasing we shall next examine; and here we must fetch our information from the Mechanism or manner of proceeding in this operation; which, as I have been inform'd, is no other then this.

They double all the Stuff that is to be water'd, that is, they crease it just through the middle of it, the whole length of the piece, leaving the right side of the Stuff inward, and placing the two edges, or silvages just upon one another, and, as near as they can, place the wale so in the doubling of it, that the wale of the one side may lie very near parallel, or even with the wale of the other; for the nearer that posture they lie, the greater will the watering appear; and the more obliquely, or across to each other they lie, the smaller are the waves. Their way for folding it for a great wale is thus: they take a Pin, and begin at one side of the piece in any wale, and so moving it towards the other side, thereby direct their hands to the opposite ends of the wale, and then, as near as they can, place the two opposite ends of the same wale together, and so double, or fold the whole piece, repeating this enquiry with a Pin at every yard or two's distance through the whole length; then they sprinkle it with water, and fold it the longways, placing between every fold a piece of Pastboard, by which means all the wrong side of the water'd Stuff becomes flat, and with little wales, and the wales on the other side become the more protuberant; whence the creasings or angular bendings of the wales become the more perspicuous. Having folded it in this manner, they place it with an interjacent Pastboard into an hot Press, where it is kept very violently prest, till it be dry and stiff; by which means, the wales of either contiguous sides leave their own impressions upon each other, as is very manifest by the second Figure, where 'tis obvious enough, that the wale of the piece A B C D runs parallel between the pricked lines e f, e f, e f, and as Rh