A Supposition How the White Matter is Produced, Which Floats About in the Air in Autumn; In a Letter from the Same to Mr. Baker

away.—After this Separation the Fish that remained with me was so affected, that for three Weeks it would eat nothing I could give it; and therefore, fearing it would die to Death, I sent it to the Gentleman on whom I had bestowed its Companion; and what is very extraordinary, upon being put together again, it ate immediately, recovered its former Briskness, and both of them are still alive. I have made abundance of other Observations on Fish, but shall only add at present, that when they remain supine and unactive, they every now-and-then gape and yawn, as most Land Animals do, when weary of the Situation they are in. I remain, SIR, Norwich, July 9. 1746. Yours, &c. W. Arderon. XVI. A Supposition how the white Matter is produced, which floats about in the Air in Autumn; in a Letter from the same to Mr. Baker. SIR, Norwich, Aug. 28. 1746. HAVING lately a large Spider in my Hand, by chance I let it fall, and it hung by its Thread, as they very commonly do. On holding my Hand very still it readily ascended up it again; and thus, by giving it a Shake, and then holding my Hand still, the Spider ascended and descended scended a great many times. I thought, at first, it had spun a new Thread at every Descent, and was desirous to have measured how long an one I could cause it thus to spin; but, upon a stricter Examination, I very plainly perceived, that whenever it ascended, it wound its Thread with its Feet into a sort of Coil, and when it descended only ravelled it out again. The Manner how they perform this is diverting enough; but as Spiders may be had almost in every Place, and the Experiment is so easily tried, I shall forbear describing it; and only add, that as these Coils of Thread are exactly like those floating in the Air towards the End of Summer, I think it is not improbable those are made in the same Manner, when Spiders have a Mind to direct their Course in the same Direction their Threads lie. XVII. Some Remarks on the precious Stone called the Turquoise; by Cromwel Mortimer, Sec. R. S. &c. Read Feb. 26. 1746-7. THIS Stone has received its modern Name of Turchesia, and Turquoise, from its being most commonly brought from Turkey into various Parts of Europe. De Boodt * says, the Colour of this Gem is a Variegation of Green, White, and Blue; and that there are two Sorts of it, the oriental, from the East Indies and Persia, and the occidental, * Gemmar. et Lap. Hist.