reader a better idea of the subject, we shall adduce an instance of profit, in 1814, upon five ounces of eggs :

pro

In this calculation, however, it ought not to be forgotten, that the price of cocoons in the year above mentioned was remarkably high: perhaps we shall not be wide of actual fits, therefore, upon an average of five years, if we reduce the 799 Milan livres to 476, which even then leaves a profit more than adequate to the capital engaged and the labour employed.

Thirty-nine thousand eggs, of the common breed of four casts, weigh one Italian ounce. Five ounces produce from 150,000 to 195,000 silk-worms. These require 8250 pounds of grafted mulberry-leaves, and will produce 600 pounds of cocoons, which, in common years, will sell for 1000 Milan livres.

It appears that, supposing twenty-one pounds of mulberryleaves yield one pound and a half of cocoons, the profit will be adequate that thirty-five days, the period, of attention, and during which period there is little to do, the cultivator gains a sufficiency for himself and family for many subsequent months; and that any individual, renting a spacious laboratory, and an ample supply of leaves, may realize a considerable income. In regard to the national increase of wealth, it is clearly demonstrable, that Italy can produce exportable silk to the amount of 42,800,000 Milan livres, at the same time leaving a very considerable quantity for homeconsumption.

Silk, unlike any other wearable commodity, will never cease to be eagerly sought after among all civilized nations.

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'No natural or artificial production,' as the translator justly observes, can vie with silk either in magnificence or brilliancy. Courts and nobles may in vain seek, in any other material, ornaments to gratify their vanity or their luxury; and the temples of religion can find nothing more sumptuous to decorate their high solemnities.'

But the most important part of the subject at present is the consideration, whether the soils of England and Ireland are adapted to the growth of the white mulberry, (the most profitable food for the silk-worm,) and whether the proper temperature can be attained and preserved with precision.

It is certain that the rearing of silk-worms has been successfully practised in this country, on a small scale, and it is equally certain that they have failed on a large one; and this simply from the circumstance, that the genial temperature and the necessary degree of ventilation have not been sufficiently observed. These two subjects being adequately understood and acted upon, we see no obstacle whatever to the rearing as many silk-worms as the cultivators can procure subsistence for. It is to be observed, that if it be necessary to guard the insect from the cold in these islands, it is equally incumbent in Italy to guard them from the heat, the one being fully as detrimental to the insect as the other.

In hot climates, the worms are always in contact with the open air; they, therefore, are never injured by gases and mephitic vapours. Passing into climates in which laboratories are requisite to screen them from the cold, and deriving sustenance from a tree, which, like most others, is deteriorated by uncongenial soils, the insect itself has undergone particular modifications, and these have produced new varieties, in the management of which the principal thing to be consulted is temperature. This arises chiefly from the circumstance, that having neither red nor warm blood, its entire animal heat is regulated by the temperature of the atmosphere in which it lives, having eighteen organs of respiration.

In Europe the temperature is regulated in the laboratories by the thermometer; and another useful instrument, also, is used, invented by M. Cluson Bellani de Monza, called the Thermometrographe, which indicates the different extremes that have occurred in the temperature in a particular space of time. By the use of an eudiometer, too, may be ascertained, at any moment, the vitiated state of the air in any part of the laboratory. The difference between feeding the worms in darkness or in light is extremely important, as the following curious observations will show :

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< There is in the order of nature a certain and very surprising fact; when the leaves of vegetables are struck by the sun's rays they exhale an immense quantity of vital air necessary to the life of animals, and which they consume by respiration.

، These same leaves, in the shade, and in darkness, exhale an immense quantity of mephitic or fixed air, which cannot be breathed, and in which animals would perish.

This influence of the sun does not cease, even when the leaf has been recently gathered; on the contrary, in darkness, gathered leaves will exhale a still greater quantity of mephi

tic air.

'Place one ounce of fresh mulberry-leaves in a wide-necked bottle, of the size of a Paris pint (containing two pounds of liquid), expose this bottle to the sun about an hour afterwards, according to the intensity of the sun; reverse the bottle, introduce a lighted taper into it, the light will become brighter, whiter, and larger, which proves that the vital air contained in the bottle has increased by that which has disengaged itself from the leaves; to demonstrate this phenomenon more clearly, a taper may be put into a similar bottle which only contains the air which has entered into it by its being uncorked.

Shortly after the first experiment, water will be found in the bottle that contained the mulberry-leaves; this water evaporating from the leaves, by means of the heat, hangs on the sides, and runs to the bottom, when cooling; the leaves appear more or less withered and dry according to the quantity of liquid they

have lost.

'Put in another similar bottle an ounce of leaves, and cork it exactly like the former; place it in obscurity, either in a box, or wrap it in clothes, in short, so as totally to exclude light; two degrees after, according to the temperature, open the bottle, and put either a lighted taper, or a small bird into it, the candle will go out, and the bird perish, as if they had been plunged into water, which demonstrates that in darkness the leaves have exhaled mephitic air, whilst in the sun they exhaled vital air.

I do not think it can be necessary to make the exact calculation of the deterioration of the air caused by more or less vegetable substance, when exposed to darkness. The two extremes I have just proved by the experiment are sufficient to give an idea of it.

Besides, light volatilizes any watery vapour with which it is in contact; there is therefore no doubt, that, all circumstances equal, the air of a well-lighted laboratory will be drier than that of a laboratory which is dark.

'Many think that light is injurious to silk-worms. It is certain that in their native climate it does not injure them, although they are exposed to it by various circumstances; however, there is here no question of exposing them to the sun, but only of rendering their habitations as light as our own.

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I have always observed, that on the side on which the light shone directly on the hurdles, the silk-worms were more numerous and stronger than in those places where the edge of the wicker hurdle intercepted the light, and formed a shade, which is my reason for having very low edges to the wicker trays: any body may make this observation. I have even seen the sun shining full on the worms, without their seeming annoyed by it. If the rays had been too hot, and shone too long on them, they might have suffered; but this could not occur, nor does it affect the question: as I do not propose exposing the silkworms to the sun, but only desire to show that the air is more vitiated, and that there is more damp in a dark laboratory than in a light one.'

As the Chinese insist that silk has been known in the southern provinces of that vast empire from a period 2700 years anterior to the Christian era, it has been supposed, with much probability, that the silk-worm was, originally, a native of China; whence it is supposed to have passed into India, Persia, and Arabia. It was an article of commerce at Tyre, in the reign of Solomon: but it was not till many centuries had elapsed, that silk-worms were conveyed to the island of Cos, whence, in the sixth century, they were introduced into Constantinople by the Empress Theodora, at whose instance Justinian was induced to make their cultivation an object of public interest. From Constantinople they passed into the Morea, Spain, Italy, and France.

Though warm countries are, undoubtedly, most congenial to the silk-worm, silk has been reared not only in Germany, Bavaria, and Prussia, but in Russia; and in a latitude, too, as high north as 54°, with such success as to warrant the establishment of manufactories for the working the native silk. A hope is even entertained that, in the course of a few years, that country will be entirely independent of Persia for this valuable article.

It appears, too, and these are circumstances which ought to command considerable attention, that silk grown in. northern latitudes is far superior in point of fineness and solidity to that produced in Italy; that it supports the preparation and dye as well as the best silk of India, and, at the same time, is entirely equal to it in softness and brilliancy.

The only question then that remains is, whether there be now growing in this country a sufficient quantity of white mulberry-trees to enable us to improve our present silk-wormpopulation to any extent. And here the grand difficulty lies. For if it require 21,000 pounds of leaves to yield 1500 pounds of cocoons, it must be evident to any one duly acquainted with

the

the rural economy of this country, that if we would cultivate silk largely we must either import leaves, a hazardous, and, indeed, an impossible undertaking, because heat and accumulation spoil the leaf, or wait several years. It is true, there is, near London, a plantation of several thousand white mulberries, some of which are stated to be fifteen or sixteen years old: but these were planted in so uncongenial a soil, that the Company before alluded to are, we understand, at this very moment removing them to a better. With the exception of these, we are not acquainted with any mulberry-plantations to any extent. In the south of Ireland, during the latter part of the last century, some French refugees planted no inconsiderable number. But those persons subsequently returned to their own country, and the landlords, upon whose lands the trees were planted, cut them all down soon after their departure. This barbarism is the more to be lamented, since Ireland, both from soil and temperature, is peculiarly well adapted for the purpose. In full persuasion of this, several noblemen and gentlemen, possessing large estates in that country, have undertaken to devote a portion of their lands to mulberry-cultivation; among whom we may particularly distinguish the Marquis of Lansdowne, the Marquis of Downshire, the Earls of Kingston and Carrick, the Irish Attorney-General, and Sir John Newport.

The style of this translation is perspicuous, and the subject of it one that deserves the general attention of the country.

ART. IV. The Beauties of Wiltshire, displayed in Statistical, Historical, and Descriptive Sketches: interspersed with Anecdotes of the Arts. By J. Britton. Vol. III. 8vo. 1l. 4s. Printed for the Author; and sold by Longman and Co. 1825. THIS HIS publication is part of a work, of which the two first volumes were produced so long as twenty-five years ago. The author acknowledges the delay with compunction; but consoles himself under the rebuke, which he cannot wholly avert, by a complacent reference to his literary labours during the intermediate time, labours, which he skilfully enough entitles occupations in the service of the public. It is quite true that Mr. Britton was not idle on other matters; and though we should have been better pleased that,

The two first volumes were noticed in the xxxviiith vol. of the M. R. N.S.

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