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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1825 edition. Excerpt: ... The average length of the silk-worms, which was six lines after the second moulting, is become, in less than seven days, above twelve lines. The weight of the insect has increased fourfold in the same period; after the second moulting 610 worms made an ounce, now 144 only will complete that weight. It has been sufficient during this age to open the ventilator, the door, and even ithe windows, when the weather was still and fine, so as to lower the temperature by a degree only. In the damp close days, a light wood-fire, in the fire-place, renews the air by drawing a current, without fear of injuring the interior atmosphere. During this age, it never happened to me to experience the exterior temperature, although higher than the interior, to be beyond the prescribed limits. 4. Rearing of the Silk-worm in the Fourth Age. In this age, the worms proceeding from five ounces of eggs should occupy a space of about 412 feet square, which should be distributed in a manner similar to that practised in the former age. The temperature of the laboratory should be . from 68 to 71 . In this fourth age, as in the fifth, there will probably be days in which it will not be possible to maintain the temperature of 71, because of the heat of the weather, as the season advances; and in spite of artificial means, it may very probably rise to 73 or upwards. This augmentation of temperature need create no anxiety, because it does no harm. It is sufficient to prevent the circulation of air being interrupted. The moment it is perceived that the exterior atmosphere begins to heat the laboratory, the ventilators should be opened as.well as all apertures on the side unexposed to the sun. I have seen, in the space of two hours, some of my...

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