[No. oi5. 137 



be raised at pleasure by a pulley. Also an upright ventilator on tbe 

 roof filled with blinds, through which a constant draft may be kept 

 up. The windows may be filled with oil paper, or cloth, which will 

 admit the light and exclude the sun. 



In one end of the building, in each of the doors, there should be a 

 ventilating wheel, made of thin boards, much after the form of the 

 wheels applied to the stern of our steam propellers. These wheels 

 should be about two feet in diameter. They should be put in mo- 

 tion for a few minutes every hour or oftener, in still weather. Both 

 may be made to turn by one crank, connecting each, by bands and 

 wheels, to the main shaft. 



An air furnace, such as is now employed in heating churches and 

 other buildings, should be constructed in the cellar, and so arranged 

 as to draw directly from the feeding rooms all the air necessary to 

 supply the furnace. The air, when heated in the chamber, should 

 be conveyed through the whole length of the rooms in a square 

 wooden box, with openings at short distances from each other, 

 which should increase in size as they recede from the furnace. These 

 openings may be so connected as to be all closed at once. When 

 the temperature is sufficiently high in the room, theyjmay be closed, 

 suffering the hot air to escape outside of the building. In the last 

 ages of the worms, the furnace will be found of great benefit, even 

 when the heat is not required in the room, for the purpose of draw- 

 ing off and consuming the impure air of the cocoonery. 



At Economy, they not only make use of air furnaces, but in an 

 adjoining building, they have a large air pump constantly in operation, 

 connected with the cocoonery by a pipe, with small openings 

 through the length of the building. This pump is kept in motion be 

 a steam engine. 



With good eggs, where proper means have been employed for 

 their preservation, and the feeding apartments thoroughly ventilated, 

 I do not know of a single instance where the worms have proved 

 unhealthy. 



From the conviction that proper regard had not generally been 

 paid to the ventilation of cocooneries, in the summer of 1842, I com- 

 menced a series of experiments, by which I ascertained that the silk 

 worm, during its last age, consumed near its own weight oj food daily 

 and that the amount of exhalations or imperceptible perspiration given 



