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resorted to in European countries to keep up this uniformity does not 

 become so necessary in this State as in those countries, and if resorted 

 to and used here when unnecessary, the result is a positive injury. To 

 comprehend this proposition, it must be remembered, that, as a general 

 fact, any particular substance or body is a much better conductor of heat 

 or caloric when saturated with water than when dry. Thus, with a 

 certain thickness of dry cloth we may handle a hot iron, but if the same 

 cloth be wet or damp it proves but little protection. The same rule 

 holds good in handling a piece of iron full of frost. In the former case, 

 the humidity, or water, conducts the heat from the iron to the hand, 

 while in the latter it conducts the heat from the hand to the iron. In 

 both instances suffering is the result. By an application of the same 

 principle to the atmosphere in which we live and breathe, and which is 

 constantly touching us, both externally and internally, we may discover 

 the reason why we suffer so much more from changes of temperature in 

 a damp climate than in a dry one. In other words, why, at a given low 

 temperature, as indicated by the thermometer in the former, we need 

 artificial heat to keep us comfortable, while, at the same indicated tem- 

 perature in the latter, we are comfortable without it. Also, why, at a 

 given high temperature, indicated in the same manner in the damp 

 atmosphere, we feel oppressed with the heat, while in the dry we feel no 

 inconvenience. 



The silkworm, for the same reasons, undergoes a similarly increased 

 degree of suffering in a damp climate, both from heat and cold, or from 

 a high and low indicated temperature, while in a dry climate, for the 

 same reasons, the changes in the temperature have a less effect upon it. 

 This theory is strikingly proven to be sound by facts. All the authori- 

 ties written from a European experience lay down the rule that the tem- 

 perature of a cocoonery, in which worms are fed, must not be allowed 

 to sink below sixty-five degrees, nor to rise above seventy-five degrees, 

 while the experience in this State is that the worms remain lively and 

 eat well at sixty degrees, and suffer no inconvenience at eighty degrees 

 and even ninety or one hundred degrees of natural heat Hence we may, 

 in all ordinary seasons in California, dispense with artificial heat and all 

 apparatus for decreasing the temperature of the atmosphere. Nature 

 here seems to have provided the most favorable conditions for the suc- 

 cessful rearing of the silkworm, and any interference with those condi- 

 tions has, in every instance thus far, proved detrimental. 



If artificial heat be resorted to at all, my opinion, formed from the 

 experience of the p%st season, is, that it should only be used in extreme 

 cases — say when the mercury falls below sixty degrees, and then only 

 with great care that the cocoonery is well ventilated. Artificial heat 

 seems to magnfty any impurity in the air, and should only be considered 

 and used as a substitute for a greater evil. It may well be doubted 

 whether the change of the temperature, as produced by the natural 

 changes of day and night, is not better adapted to the nature and con- 

 sequent health of a worm than a uniformity of temperature at any 

 particular degree, sustained by artificial heat, however applied. No 

 animal or insect can eat all the time, and a wise Providence has 

 appointed the night for a time of rest for all His creatures. Indeed, 

 when I study the history of the silkworm, in connection with the habits 

 of the people in the different countries in which silk culture is made a 

 leading industry, I am led to doubt whether too great a departure from 

 nature in the treatment of the worm has not been in some way the 

 prime cause of the disease so prevalent in European countries. One 



