8^ 



FARMER S ' fl ii G I S t E R 



conducted into one leading from the furnace con- 

 Etrucied lor healing the air-chamber, the draught 

 lurnace at the boiiom ot the chimney, and ven- 

 tilating wheel above, both operate to the same 

 tnd, namely, that ofaivvays producing the proper 

 flegree of ventilation in the cocoonery. In cases 

 v\ here the external air is too warm ami it becomes 

 recessary to cool it down by means of ice, or 

 oiherwise, belbre introducing itinio ihe apartment 

 containing the silU-worms, the ventilating wheel 

 may be brought into action. 



In his general considerations upon the adoption 

 of this plan lor artificial veniilaiion in cocoont-ries, 

 JD'Arcet observes;— If there be an established 

 principle in Hygiene, it is above all others that 

 which makes the breathing of li-esh air necessary 

 for the preservation of good health in animals ol 

 every description. Intelligent persons are unani- 

 mous in their opinion upon this point. The sub- 

 ject therelore needs no farther discussion in regard 

 to the main principle, and its applicability to co- 

 cooneries. The only remaining question is as to 

 the choice of means best calculated to efiecl the 

 proper ventilation in such establishments. 



Upon reading what has been published upon the 

 Bubject of rearing silk- worms in China, we find that 

 Irom the earliest periods the Chinese have recog- 

 nised the necessity of preserving the irrcalest pu- 

 rity in the air of their cocooneries. We are, how- 

 ever, obliged to acknowledge that the means they 

 adopted for this purpose were very imperlect. To 

 renew the air of a cocoonery by opening to a greater 

 orless extent its windows and doors, shows the 

 infancy of the art. JtR efl'ects are to renew the air 

 unequally ; to produce sudden changes of tem- 

 perature with irregular currents, annoying to the 

 worms nearest the openings, and insufficient lor 

 those situated lirirthest liom the doors and windows 

 as well as in the corners of the apartment. 



The deficiency of scientific knowledge in China, 

 its immense population and the low price of labor 

 in the country, are circumstances which atl'ord an 

 explanation of the imperfeciion which exists in the 

 means employed for the ventilation of cocooneries, 

 and the success of their rearing. Eut this success 

 is only to be attained at the expense of time and 

 attention. In France we may and we should do 

 better. 



Whilst engaged in applying means (or the re- 

 storation of health to cocooneries that had been 

 long in use, I ascertained how very rapidly the air 

 became vitiated in those apartments where a large 

 quantity of ammonia Harmed and accumulated. 1 

 tfierefore saw the great necessity of contriving the 

 means by which a regular and active ventilation 

 might be eli'ected, and the air constantly maintain- 

 ed in a healthy condition. The system of ventila- 

 tion which I have described in my memoir upon 

 healthy cocooneries, has appeareil to me the most 

 convenient for adofition, because it spreads the 

 current of air through the apartment evenly and 

 slowly ; it is at the same lime simple and economi- 

 cal, easy of application, admitting ol" every de- 

 gree of (juickness in the current of air, and, when 

 necessary, of an instantaneous check. Tlie |)lan 

 has been in use lor three years, and has perlectly 

 answered my expectations. The extensive cor- 

 respondence which 1 have kept up in relation to 

 ihe subject has afl'orded the most positive evi- 

 dences, that the system, even when imperlijctly ap- 

 plied, ban been productive oft he most happy results. 



Some persons have thought that the plan of ar- 

 tificial or forced ventilation, such as I have de- 

 scribed, must be attended with injurious effects 

 upon the health of silk- worms in consequence of its 

 too great violence. But this charge is wholly 

 contradicted l»y the expedience of three years, du- 

 ring which time, in all that has been said and 

 written upon the subject, not one objection has 

 been made against the too great rapidity of the 

 current of air in the salubrious cocooneries erected 

 according to my [dan. On the contrary, I have 

 been questioned, especially by the silk culturists of 

 the south, upon the propriety of increasing the 

 l)ovverol the ventilating apparatus, a thing most 

 readily accomplished wheievprit maybe required; 

 fcinee it is only necessary to raise the height ol'the 

 main chimney, increase the size and velocity of 

 the ventilating wheel, and employ the means of 

 veniilaiion with more or less force, according to 

 the atmos()hcnc conditions which may exis'. 



The loicing systen) of ventilation ap|)lied to co- 

 cooneries has lor its principal object the withdrawal 

 ol' vitiaied air Irom apartments, and the gradual 

 substitution of pure air. But its advantages are 

 not limited to preserving the health of the silk- 

 worms and persons employed in the cocoonery. 



It is recognized as a piinciple, the truth of which 

 has been confirmed by actual experience, that it i? 

 easier to raise than to cool dowiiihe temperature of 

 the ventilating current. In some situations and 

 under certain circumstances, it is necessary lo re- 

 duce the temperature of the air, in order to effect 

 the most proper ventilation in cocooneries, and 

 obtain the greatest possible product from the rear- 

 ing. Now the Ibregoing system of \eniilation 

 otjers the most convenient means of efieciing this 

 object, in the following manner. 



When the ventilating current introduced into an 

 apariment is not saturated with watery vapor, it is 

 evident that its temperature will be lowered by 

 coming into contact with wet or moist bodies. 

 When, therefore, it becomes necessary to cool 

 down the temperature of the air, and when this 

 mitsl be done without the use of ice, it may be 

 conveniently effected by sprinkling water in the air 

 chamber, and upon the floor of the cocoonery, or 

 by suspending in this wet cloths. I will not lar- 

 tfier dwell upon the employment of these means 

 of which 1 have said so much in my memoir. 

 But 1 will observe that silk-worms transpiring 

 freely, and, together with the fresh leaves, being 

 exposed on all sides to a current air, must neces- 

 sarily have their temperature reduced below that 

 of the surrounding air, a proper regulation of 

 which cannot help being advantageous under the 

 circumstances relerred to. As to those persons 

 employed in Ilie cocoonery, and whose natural 

 temperature is fixed above that of the air, the cur- 

 rent refreshes them in the same manner that it 

 does out of doors, on v/hich account it will be 

 equally beneficial to them as to the silk-worms. 

 An application of these observations will tend 

 greatly to establish the correctness of the preced- 

 ing remarks. 



Supposing that we had to superintend a rearing 

 in the south of France, and that the air was to get 

 into the calm and sultry condition which they term 

 in tliose countries tovffe. In this case if" the 

 cocoonery was not well ventilated there would be 

 no means of checking the progress of infection and 

 preventing the death ol" the silk-worms in tlie 



