some interesting specimens of mummy cloth sent to this country by the then Consul-general of Egypt, the late Mr. Salt. The subject appearing to me sufficiently interesting to deserve investigation, and having collected a variety of specimens of cloth, my first care was to ascertain of what material they were made. This question had already engaged the attention of various inquirers, and given birth to learned dissertations.

Rouelle, in the Memoirs of the French Academy of Sciences for the year 1750; Larcher, the translator of Herodotus, in the notes of that celebrated work; and the learned John Reinhold Forster, who wrote a tract De Bysso Antiquorum, had all. endeavoured to prove from their own examination, that the mummy cloth of Egypt was cotton: and this opinion, on their authority, was adopted by the learned of Europe. It is singular that neither in the memoir of Rouelle, nor in the notes of Larcher, nor in the dissertation of Dr. Forster, in which this opinion is expressed, are any grounds assigned for, or any proofs given of this opinion. The amount of their assertion is, that having examined the bandages of various mummies, which are designated by them, and some of which I have myself since carefully examined, they found all those which were free from resinous matter to be cotton. I am forced to confess, that with all the attention I could bestow upon them, and with the assistance of various intelligent manufacturers, I was unable to arrive at such a conclusion. Some were of opinion that the cloth was cotton; others that it was linen; and some again, that there were in the collection specimens of both,-a proof that our means of judging were unworthy of confidence.

The great difference in the specific gravities, as well as in the conducting power of linen and cotton, is sufficient to enable us, by careful experiments, to discriminate accurately between them; and there are few individuals, who have been accustomed to the use of both cotton and linen, who cannot readily distinguish, by that delicate sense of touch diffused over the whole body, between the two fabrics: but such tests require much larger portions of the material than I had at my disposal, many of the specimens submitted to my examination not being larger than a shilling. I found the difference of smell in the burnt fibres, and the degree of polish which each kind of cloth took on being rubbed with a glass stopper, as well as other empirical modes suggested to me, liable to great uncertainty, and I sought in vain for

any chemical test. It occurred to me that the supposed unfitness of cotton lint, compared with linen, for dressing wounds, had been accounted for by the different form of their fibres, the one being sharp and angular, and the other round and smooth; and, in fact, I found in the 12th volume of the Philosophical Transactions, for the year 1678, this structure ascribed to them by that early microscopic observer, Mr. Leuwenhoek. It seemed to me, therefore, that the most simple mode of distinguishing between cotton and linen would be to subject the fibres to examination under a powerful microscope. Not being possessed of such an instrument, nor accustomed to its management, my friend Mr. Children undertook, through Sir Everard Home, to solicit the assistance of Mr. Bauer, whose labours are well known to the scientific world, and whose microscopic drawings have for a series of years enriched the transactions of the Royal Society. I transmitted to him various fibres of cotton and linen, both manufactured and in their raw state, as well as fibres of unravelled mummy cloth; and in a few days I received from him a letter, in which he pronounced every specimen of mummy cloth subjected to his examination to be linen.

This letter was accompanied by a beautiful drawing, exhibiting the fibres of both raw and unravelled cotton as flattened cylinders, twisted like a corkscrew, whilst the fibres of linen and various mummy cloths were straight and cylindrical.

Repeated observations having established, beyond all doubt, the power of the microscope accurately to distinguish between the fibres of cotton and linen, I obtained, through the kindness of various individuals connected with the British Museum, the Royal College of Surgeons, the Hunterian Museum of Glasgow, as well as other public institutions, both at home and abroad, a great variety of cloths of human mummies, and of animals and birds, which, being subjected to the microscope of Mr. Bauer, proved, without exception, to be linen; nor has he, amongst the numerous specimens we have both collected during many years, been able to detect a single fibre of cotton; a fact since recently confirmed by others, and proving incontestibly that the mummy cloth of Egypt was linen.

II.

The filaments of cotton, when viewed through a powerful instrument, such as the improved achromatic microscope of

Ploessl, of Vienna, which for magnifying power and clearness of vision Mr. Bauer has found superior to every other he has had an opportunity of using, appear to be transparent glassy tubes, flattened, and twisted round their own axis. A section of the filament resembles in some degree a figure of 8; the tube, originally cylindrical, having collapsed most in the middle, forming semi-tubes on each side, which give to the fibre, when viewed in certain lights, the appearance of a flat ribbon, with a hem or border at each edge. The uniform transparency of the filament is impaired by small irregular figures, in all probability wrinkles or creases arising from the desiccation of the tube. The twisted and corkscrew form of the filament of cotton distinguishes it from all other vegetable fibres, and is characteristic of the fully ripe and mature pod, Mr. Bauer having ascertained that the fibres of the unripe seed are simple untwisted cylindrical tubes, which never twist afterwards if separated from the plant; but when the seeds ripen, even before the capsule bursts, the cylindrical tubes collapse in the middle, and assume the form already described, and which is accurately delineated in the accompanying drawing.

This form and character the fibres retain ever after, and in that respect undergo no change through the operation of spinning, weaving, bleaching, printing, and dyeing, nor in all the subsequent domestic operations of washing, &c., till the stuff is worn to rags; and then even the violent process of reducing those rags to pulp for the purpose of making paper, effects no change in the structure of those fibres. "With Ploessl's microscope," says Mr. Bauer, "I can ascertain whether cotton rags have been mixed with linen in any manufactured paper whatever."

The elementary fibres of flax (linum usitatissimum) are also transparent tubes, cylindrical, and articulated or jointed like a This latter structure is only observable by the aid of an excellent instrument. They are accurately delineated in the annexed engraving.

cane.

Explanation of Plate A.

First row of figures: A. Fibres of the unripe seed of cotton. In that state the fibres are perfect cylindrical tubes. At is a fibre represented as seen under water, showing that the water