RESOURCES OF AMERICA, SILK, ETC. 421 



times a day during the third and fourth ages ; and eight times a day 

 during the fifth, or last, and longest age, during which they eat 

 many times more than during all the previous ages the most per- 

 fect cleanliness and a pure atmosphere being at all times preserved 

 as indispensable. 



In conjunction with this high temperature and continued feeding, 

 a certain degree of moisture or constant dampness is indispensable; 

 since it is found that a drying heat has the effect, not only to absorb 

 suddenly all the moisture of the leaves, thus rendering them unfit 

 for food, but to absorb also the moisture from the luntrs and bodies 

 of the insects. With a temperature of 81 to 84 of Fahr., a degree 

 of moisture must be preserved, equal to from 85 to 89 of Saussure's 

 hygrometer. Without this suitable degree of moisture, a high tem- 

 perature was found by M. Beauvais to be utterly destructive. The 

 same destructive effect, it is well known, is produced on the human 

 system from similar causes. By this system of management he has 

 also ascertained that the worms eat more, while the consumption of 

 leaves is diminished, because they make much less litter and waste; 

 the education being completed with a very great saving of time, 

 and, consequently, economy in all things. So great was this saving, 

 that, in 1836, the whole process was completed in twenty-one days, 

 while in a common temperature it lasts usually from thirty-one to 

 thirty- three days. 



CHAPTER XI. M. D'ARCETS SYSTEM OF VENTILATION. 



The salubrious Magnanarie, or healthy cocoonery of M. D'Arcet, 

 is described as consisting of an oblong building with four ranges of 

 hurdles ; in the end is a brick flue or chimney, and near this tie ap- 

 paratus for warming the apartments, when required, is placed, in the 

 cellar. This may consist of nothing more than a common cast-iron 

 box stove, the stove a little elevated. This stove is surrounded on 

 all sides, except the front, with a single wall built up roughly of 

 brick work, as high as the floor, leaving a space of about a foot, on 

 three sides of the stove, with a few openings at the bottom of the 

 brick wall, for the admission of cold air from without ; this space 

 forms the air-chamber. The stovepipe rises a few feet; then, de- 

 scending within this narrow space, it passes off horizontally through 

 this brick work into the chimney. A little fire being kindled within 

 the stove, the cold air within the air-chamber, becoming heated, rises 

 to the top ; thence dividing into four main branches, it is carried, by 

 four main horizontal tubes of wood, beneath the floor, and directly 

 beneath the hurdles. From these wooden tubes the heated air is 

 permitted to escape upwards through the floor by numerous holes 

 or openings, which are about two and a half feet asunder : these 

 holes are of unequal size, the first being about an inch square, the 

 size of each gradually increasing, as the current diminishes con- 

 tinually as it proceeds. In the garret, corresponding wooden tubes 

 are used, with holes Opening downwards through the ceiling. 

 These tubes, uniting in one, enter the chimney ; these carry off the 

 impure or cold air of the whole apartment. Near the chimney, and 

 in the garret, and connected with these tubes, is a fan-wheel or 

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