In constructing the body of the nest, the most remarkable circumstance is the using of her limbs as a measure, to regulate the distances of her _radii_ or wheel-spokes (See Fig. 12. Plate IV., which represents the geometric net of the “_Epeira diadema_”), and the circular meshes interwoven into them. These are consequently always proportional to the size of the spider. She often takes up her station in the centre, but not always, though it is so said by inaccurate writers; but she as frequently lurks in a little chamber constructed under a leaf or other shelter at the corner of her web, ready to dart down upon whatever prey may be entangled in her net. The centre of the net is said also to be composed of more viscid materials than its suspensory lines,--a circumstance alleged to be proved by the former appearing under the microscrope studded with globules of gum[174]. “We have not been able,” says Mr. Rennie, “to verify this distinction, having seen the suspensory lines as often studded in this manner as those in the centre.” [174] Kirby and Spence, Intr. i. 419. At the commencement of the last century a method was discovered in France by Monsieur Bon, of procuring silk from spiders’ bags, and its use was attempted in the manufacture of several articles. Mr. Bon has, however, noticed only _two_ kinds of silk-making spiders, and these he has distinguished from each other as having either long or short legs, the last variety producing the finest quality of raw silk. According to this ingenious observer, the silk formed by these insects is equally beautiful, strong, and glossy with that formed by the silk-worm. When first formed, the color of these spiders’ bags is gray, but, by exposure to the air, they soon acquire a blackish hue. Other spider bags might probably be found of different colors, and affording silk of better quality, but their scarcity would render any experiment with them difficult of accomplishment; for which reason M. Bon confined his attention to the bags of the common sort of the short-legged kind. These always form their bags in some place sheltered from the wind and rain, such as the hollow trunks of trees, the corners of windows or vaults, or under the eaves of houses. A quantity of the bags was collected from which a new kind of silk was made, said to be in no respect inferior to the produce of the silk-worm. It took readily all kinds of dyes, and might have been wrought into any description of silken fabric. Mr. Bon had stockings and gloves made from it, some of which he presented to the Royal Academy of Paris, and others he transmitted to the Royal Society of London.