shorter shape. It is an error to suppose, that hats are made from rye, or any other grain in Tuscany. This marzolano straw is cultivated for the sole purpose of being made into hats; and is grown chiefly in the vicinity of Florence, and on the hills on both sides of the valley of the Arno. The growth of the straw is thus almost exclusively confined to a limited part of the province of Tuscany. A few years ago, the Pope, aware of the source of wealth which this manufacture produced in that quarter, attempted to introduce the culture of it into his States. From the habits of the people, difference of soil or climate, or from all these causes conjoined, the plan did not succeed; and the Grand Duke of Tuscany having now allowed the prepared straw to be exported, the idea of cultivating it elsewhere seems to be altogether abandoned. Tuscan women, in the mean time, have settled themselves in various places, such as Vienna, Petersburgh,. &c., where they carry on the manufacture with straw grown in Tuscany.

"The seed is sown on good ground, but not rich; some sow it on poorish land. In general, vines and olives bound the fields in which it grows, or are planted at intervals in the interior of these fields, like orchards in this country. The practice in sowing flax is known to every agriculturist; and nearly the same holds in regard to the marzolana, where the qualities especially to be obtained, are fineness, tenacity, and toughness.

"To obtain the first, it is sown so thick, that each blade touches another. Manure is never made use of on the ground to be under marzolana. The seed is sown on the ground in a flat state, and a person must be taught the method of sowing it, which is done "underhand." The seed is then covered in, by hoeing the ground with a draw-hoe, about three times the size of our common turnip-hoe. This is done as near the first of March as the season will permit. From the beginning to the middle of July (according to the season), it is ready, which is known by the ear being fully shot, but before it is formed into grain. The plant is then, if a good crop, eighteen inches in height. The straw is not cut, but plucked by main force from the soil, and then exposed for the purpose of bleaching, not in bundles, but scattered about in meadows or gravel grounds, exposed to the evening dew and the midday sun, until it is perfectly yellow; but constantly watched, to gather it together, and put it under cover at the least appearance of rain, which would spoil it, and make it turn out completely speckled. After it is sufficiently bleached, it is tied in bundles, and brought to the manufactory, where children are employed to pluck the only part of the straw which serves for plaiting, that is, what is comprised betwixt the ear and the first joint in the stalk. If the weather is fine, in fifteen days after the crop is pulled, it will be ready to work into plait, "treccie," as it is called. The natives say, that the dew tends greatly to whiten it; but if any rain falls it is ruined. The manner of separat. ing the top joints is by a smart jerk of the hand. These are made up for sale, and the remainder thrown to the dunghill, for no animal will eat it.

"To obtain the whiteness so much prized, the straw is smoked with sulphur previous to being worked; the plait is also smoked, and, lastly, the hat. About Sienna, the process is simply a little sulphur set on

fire in the bottom of a large chest, bunches of the straw being placed on long hazel rods across, and the lid shut down. Elsewhere, the articles are described as being placed in a small close room, in which a chafing dish of sulphur is placed and set fire to. Sometimes the operation requires to be done twice before it succeeds.

"The straw for use is classed or stapled like our wool. Children or inferior hands, work the course thick straw, while good hands work the fine only. Whether fine or coarse, it is only the part on which the spike grows that is made use of, and it is always the same plait, consisting of thirteen straws, which is worked. In the fine plaît, there is a very great waste of straw, as they reject all that is in the least too thick, and they cut off a considerable part of the straw where it comes near the flower spike. Fine plait is not accounted good, unless very much drawn together, for which end it is worked very wet. The bunches of straw are always put into a small jar filled with cold water, which stands beside the worker. After being smoked and pressed, the plait is made up into hats by women, who do nothing else; it is put together by the edges, not overlapped. On the operation of pressing a great deal depends. There are only two good machines for that purpose in the country.

"Such is the practice for procuring the hat-straw. What they sow for seed is in other ground: Not one-fourth of the seed is used, and the grain is allowed to come to maturity in the usual way. It is said to be a capital wheat for vermicelli, macaroni, &c. and also for making into bread.

"It ought to be taken into view, that, for the use of the manufacture in Scotland, the straw should not exceed one-eighteenth of an inch in diameter. When coarser, it does not answer the market; and much of the very finest straw is not required, because the bonnets made from it are too expensive."

Remarks on Dr Latta's Observations on the Artic Sea and Ice. In á communication from the Rev. Mr SCORESBY to Professor JAMESON *.

ON reading Dr Latta's " Observations on the Arctic Sea and

Ice +," in the last number of the Edinburgh New Philosophical Journal, I was rather surprised at the following hasty, and, if I mistake not, unwarrantable remark. Speaking of the climate of Spitzbergen, Dr Latta refers to my Account of the Arctic Regions, saying " Mr Scoresby, biassed by the indications of the thermometer, reasons himself into the supposition, that the climate, during summer, is more temperate than even

* Read before the Wernerian Society, 10th March 1827.

+ Edinburgh New Philosophical Journal, October-December 1826.

Scotland, and gives to the circle of perpetual congelation an altitude of 7791 feet,—a statement contradicted by facts."

Now, in this bold remark, Dr Latta first ascribes to me a statement I never made, that I am aware of; then bluntly says, that it is contradicted by facts! I do mention it, indeed, as a remarkable circumstance, that, on mountains of 3000 feet elevation in Spitzbergen, the snow should sometimes be wholly dissolved at their summits, when, in so much lower a latitude, Ben-nevis should occasionally exhibit a crest of snow throughout the year (Vol. i. p. 123.) But I nowhere reason myself into the supposition that the climate is therefore warmer. I only reason that "the upper line of congelation, where frost perpetually prevails," is much higher on the Arctic lands than was to have been expected from its mean temperature. applying the known law of diminution of temperature, on ascending in the atmosphere, to the summer heat of Spitzbergen, I observe, that "it will require an elevation of 7791 feet for reducing that temperature to the freezing point;" and hence I reckon this to be about the altitude of perpetual freezing,p. 126.

And,

What facts Dr Latta can bring forward, to shew that a thawing temperature never occurs so high, I know not; especially when, by observation of the thermometer, I found the temperature in Spitzbergen so high as 37° Fahr, at mid-night, at an elevation of about 3000 feet.

Not thinking it right to allow a bold assertion, which I believe to be unfounded, to pass before the Society as correct, nor an assertion declared to be dependent upon facts to retain such a basis, unless these facts can be substantiated, I have ventured to trouble the Society with these remarks. Besides, I acknowledge my feeling to be that which is no doubt common to authors, greatly averse to the charge of such theorising views as to be capable of reasoning myself into conclusions contradicted by facts; an equal aversion, also, to be charged with asserting what, to the best of my knowledge, I never did. As such, I think it behoves Dr Latta, either to bring forward the facts which contradict my statements, or to have the candour to acknowledge the mistake he has fallen into.

On the Coniometer.

Professor JAMESON.

MY DEAR SIR,

In a Letter from Professor LESLIE to

HAVING just seen a paragraph in the Annals of Philosophy

for March 1827, copied from the Annales de Chimie et Physique, in which my contrivance of an instrument to measure the specific gravity of powders is reclaimed for M. Say, Captain of Engineers, who, it seems, perished in the famous Egyptian Expedition; I trust you will allow me to offer some explanation.

I was aware that attempts had been made to apply' the law of Mariotte, in ascertaining the specific gravity of a substance which could not be immersed in water, but supposed them to have proved unsuccessful; and all this I stated at the time to the persons who witnessed my experiments. When I first visited Paris in 1802, my kind friend the late M. Guyton-Morveau shewed me an apparatus for that purpose; and it then appeared to me very clumsy and unmanageable. I have no recollection of the nature of its construction, and only a sort of faint impression that it was somehow connected with an air-pump. Indeed, were it worth while, I could easily point out two several methods of discovering, by help of a good air-pump, the absolute bulks, and consequently the specific gravities, of powders and very porous substances.

I have now looked into the article referred to in the 23d volume of the Annales de Chimie, and will most readily admit, that the Stereometer of M. Say is substantially the same as my Coniometer. But of this coincidence I was quite unconscious, when I designed my instrument. I made no boast of discovery, and only mentioned it as a simple contrivance, which could be directed to some very useful and curious researches. I permitted, indeed, a gentleman who admired its application, to draw up a popular description of it in his own way; but I deferred giving any account of it myself, till I had brought it to greater perfection, and was enabled to produce a series of correct and interesting results. So little, however, did it engage my attention, that I have suffered it to remain nine months for alteration, in the hands of the artist. A year has nearly elapsed before any chemical philosopher has challenged its originality; and Dr

Thomson, Regius Professor of Chemistry at Glasgow, whose acuteness, memory, and extensive reading, are universally acknowledged, has, within these very few days, ordered his workman in Edinburgh to execute for him a copy of the instrument. For myself, I can positively aver, that I never chanced to light on the Memoir of M. Say; and that, although I have been very diligent, of late years, in collecting philosophical apparatus, I have not found any account of his stereometer in elementary works of science, or met with that instrument in the physical cabinets I have seen either at home or abroad. I suspect it has been confined to the Polytechnic School, and am yet to learn what sorts of experiments have been made with it.

While I willingly concede, then, the right of priority, and cordially give to the late M. Say the praise of ingenuity and accuracy of conception, I must consider his stereometer as an imperfect project, and scarcely applicable, in its original form, to practice. The coniometer possesses several decided advantages over the instrument figured in the Annales de Chimie: 1st, The part for receiving the powder being long and narrow, the capsule is easily and nicely applied; but in the stereometer, the recipient is a broad shallow cup, the lid of which, fitting with difficulty, may shut up an undue share of air. 2dly, The long slender tube is easily pressed down into a wider one, containing mercury; whereas Say's instrument is plunged into an enormous cistern of mercury, or at least a very tall receiver. 3dly, In the coniometer, the scale engraved on the slender tube marks at once the absolute bulk of the powder or porous substance, or rather the weight of an equal volume of water; there is a sliding scale on the outer tube, and an adjustment for the variation of the altitude of the barometer. 4thly, The slender tube has besides another set of numbers engraved, corresponding to the triplication, as the former does to the duplication, of the volume of included air. By comparing the two results, we are enabled to determine, whether the air contained in the porous substance exists in a condensed state, and to calculate the degree of condensation. 5thly and lastly, The coniometer has already indicated some very curious and interesting results, which I regard, however, at present as only approximative. As soon as I have brought the instrument to a more perfect form, purpose to institute a series of accurate experiments with it.

I