Micrographia Restaurata, & c

An EXPLANATION of the SECOND PLATE

A Piece of fine wheal'd Taffety Ribbon

THIS Object was Sixpenny broad Ribbon, whose Substance viewed through the larger Magnifying-Glass,

A Piece of Ribbon.

appeared like Matting for Doors, or such Basket-Work as they make in some Parts of England, for Bee-Hives, &c. with Straws a little wreathed or twisted : for every Filament of the Silk (several whereof go to the forming one Thread) seemed about the Size of a common Straw, as the little irregular Pieces a b, c d, e f, shew.

Each Inch of this Ribbon appeared no less than twelve Foot square, and an Inch and an half in Thickness. The Warp or cross Threads seemed like Ropes of an Inch Dia- meter ; but the longitudinal Threads or Woof had scarce half that Thickness. If the Silk be white, it resembles Bundles or Wreaths of very clear and transparent Cylinders : if co- lour'd, cach Cylinder, in some Place or other, affords as lively a Reflection as is it were made of Glass ; insomuch that a Piece of red Ribbon exhibited as bright a Lustre as if coming from many Rubies. But such vivid Reflections are not found in hairy Stuffs or Linens.

PLATE II. FIG. 2, 3, 4. A Piece of Watered Silk

THIS Figure represents a Piece of Watered Silk, as seen through a Glass that magnified but little.

A Piece of Watered Silk.

A B signisies the long Way, C D the broad Way thereof.

This Silk appeared to the naked Eye, waved, undulated, or grain'd all over, with so curious though irregular a Variety of brighter and darker Parts as much increased its Beauty. So well known a Case seems to need very little Explication : But few perhaps have considered, that those which in one Position appear to the Light the darker Parts of the Wave, in another appear the lighter, and vice versa ; by which means the Undula- tions are continually shifting, as the Position of the Parts to the incident Beams of Light is varied. The Microscope discovers this Effect to proceed entirely from the Variety of the Reflections of Light, which the different Shape of the Particles, or the little Protu- berances of the Threads composing the Surface occasion : Those Parts of the Waves that appear the brighter, throwing towards the Eye a Multitude of small Reflections, while the darker afford scarce any.

Thus, in the present Figure, the brighter Parts of the Surface, denoted by a, a, a, a, a, &cc. consist of an Abundance of large and strong Reflections ; the Surfaces of those Threads that run the long Way, being, by the mechanical Process of Watering, plaited or angled in another Form than they were by Weaving ; for, by weaving, they are only turned circularly over and under the warping Threads, but by the Watering they are bent with an Angle or Elbow.

What is meant hereby will better be explained by the third and fourth Figures ; the former of which,

Fig. 3.

Fig. 3. a, a, a, a, a, shews the Manner how the long Threads in Weaving are turned over and under the cross Threads, the Ends whereof are repre- sented b, b, b, b.

Fig. 4. shews how the same Threads are by the Watering bent and alter'd into An- gles or Elbows of all imaginable Variety ;

Fig. 4.

whereby, instead of reflecting the Light from one Point only of the round Surface, as about c, c, c : they now, when watered, reflect its Beams from more than half the Surface, as, d e, d e, d e. These Reflections are also varied, as the particular Parts thereof are variously bent.

Dr. HOOXE, to make this fully understood, subjoins the Method of watering Silks or Stuffs ; the Substance of which, as being eurious in itself, and necessary for the Ex- planation of the Figures, we shall give with all the Brevity possible.

The Piece to be watered must be doubled its whole Length, with the right Side in- wards, exactly through the Middle, placing the two Selvedges just upon one another, and so disposing the Wheal or Rib in the doubling of it, that the Wheal of one Side may lie as near as can be parallel with that on the other ; for the nearer they come to that Position, the greater appears the Watering, and the more obliquely they lie to each other, the Waves become the smaller.