Page:Blackwood's Magazine volume 002.djvu/666
That black is a colour of maturity; and that though it appears at a very early period on the quill feathers, yet the back scapulars, and wing coverts, are never black except in a state of perfection:
Lastly, that pure white is a colour of perfect plumage.
In considering the relation which the changes of plumage bear to each other, it may be observed, with regard to all light-plumaged gulls,
That the pure white of the throat, breast, and belly, is the first of the mature colours which is acquired:
That the pearl gray, likewise a mature colour, appears soonest on the back, and latest on the hinder part of the neck and wing coverts; and that the plumage of gulls is more perfect during the breeding season than at any other period of the year.
As it is of the greatest importance in ornithology, that the descriptions of species should convey a clear and definite idea of the object described, we earnestly recommend to the zoologist the use of Werner's Nomenclature of Colours, with additions by Mr Sym, an artist of acknowledged excellence in this city, whose accurate representations are well known to the naturalists of Scotland. By the general adoption of such a work, ornithologists would be enabled to affix determinate ideas to particular terms and modes of expression, which they have hitherto been unable to do from the vague and indefinite nature of the language usually employed in describing the plumage of birds.
Remarkable Tenuity of the Spider's Thread, &c.
Of all the beautiful discoveries with which we have become acquainted, through the progress of the physical sciences, there are none more striking than those of the microscope, or which may be studied with greater ease. The application of a powerful lens to any of those minute objects which we have it daily in our power to examine, exhibits a scene of wonder, of which those who have never witnessed it cannot form an adequate idea.
In the introduction to Entomology by Kirby and Spence, there is a description of the process by which the spider weaves its web. After describing the four spinners, as they are termed, from which the visible threads proceed, the writer makes the following curious observations:
"These are the machinery through which, by a process more singular than that of ropes-pinning, the thread is drawn. Each spinner is pierced, like the plate of a wire-drawer, with a multitude of holes, so numerous and exquisitely fine, that a space often not bigger than a pin's point includes above a thousand. Through each of these holes proceeds a thread of an inconceivable tenuity, which, immediately after issuing from the orifice, unites with all the other threads, from the same spinner, into one. Hence from each spinner proceeds a compound thread; and these four threads, at the distance of about one tenth of an inch from form the thread we are accustomed to see, the apex of the spinner, again unite, and which the spider uses in forming its web. Thus, a spider's web, even spun by the smallest species, and when so fine that it is almost imerceptible to our senses, is not, as we suppose, a single line, but a rope composed of at least four thousand strands. But to feel all the wonders of this fact, we must follow Leeuwenhoeck in one of his calculations on the subject. This renowned microscopic observer found, by an accurate estimation, that the threads of the minutest spiders, some of which are not larger than a grain of sand, are so fine, that four millions of them would not exceed in thickness one of the hairs of his beard. Now we know that each of these threads is composed of above 4000 still finer. It follows, therefore, that above 16,000 million of the finest threads which issue from such spiders, are not, altogether, thicker than a human hair."
It had long been a question among philosophers, whether it was possible to render the labours of the spider subservient to the benefit of mankind. In the earlier part of last century, Bon of Languedoc fabricated a pair of the threads of spiders. They were stockings and a pair of gloves from nearly as strong as silk, and of a beautiful gray colour. The predaceous habits of these animals, however, would seem to oppose an effectual barrier to their being bred up in sufficient numbers to render such a manufactory at all productive. The following arguments, against the probability of any permanent or real advantage resulting from this attempt, were published by Reaumeur, whom the Royal Academy had deputed to inquire into the matter.
The natural fierceness of spiders renders them unfit to be bred and kept together. Four or five thousand being distributed in cells, fifty in some, one or two hundred in others, the big