And now I must devote a few words to the advisability of silk culture from a pecuniary point of view. _Bombyx mori_, or the ordinary mulberry silkworm, is, of course, the best to rear, if you can obtain healthy eggs. But this is the difficulty, and thence arises the necessity of cultivating other silk-producing species. I imagine that silk can be produced in most of the States of the Union, and manufactured from the cocoon at a large profit; but for the present, we will leave the manufacture out of the question, and consider only, whether it will not pay to rear eggs and cocoons for sale? It must be remembered that European manufacturers are at this moment largely dependent on foreign countries for the supply of both eggs and cocoons; and this, because of the general prevalence of disease among all the races of _Bombyx mori_. And now, to what extent does the reader suppose this dependence exists? Of cocoons I have no returns at hand, but, of raw silk, European manufacturers purchase, annually, not less than $160,000,000 worth; and of eggs (_Bombyx mori_) to the value of $10,000,000. This, then, is a business of no trifling amount. California seems to be alive to the fact, and, I am informed, raised, this last season, $3,000,000 cocoons; and, for sale, about 4,000 ounces of eggs, worth at least $4 per ounce, wholesale. Now, there is no earthly reason why California should monopolize this business. Why are not companies formed in other States for this purpose? or if private individuals lack the enterprise or the means, why do not the legislatures, of those States most favorably located, do something by way of starting the business? A few thousand dollars loaned, or even donated, may prove to be a valuable investment for the people at large, and, even supposing a failure, would not be a very great loss to any body. So far as farmers are concerned, it may interest them to know that one man in England, Capt. Mason, clears $50 per acre by rearing silkworms (_Bombyx mori_ in this case), and I much doubt whether any crop raised here pays as well. By way of commencement, then, let everybody that has sufficient leisure set to work, and rear as many silkworms, of the above-named species, as he possibly can; and if the process be not remunerative in a pecuniary sense, it most assuredly will be in the amount of pleasure and knowledge obtained. One caution I must give to those who cultivate _Bombyx mori_. Although _Yamamai_ requires sprinkled branches, _Bombyx mori_ does not; nor must the leaves be furnished to them while wet with rain or dew. * * * * * EFFECT OF COLD UPON IRON.--The article upon this subject, giving experiments of Fairbairn and others, referred to in our editorial upon the same subject, in our last issue, was crowded out by press of matter. The reader will find it in the present number. * * * * * UNIVERSAL BORING MACHINE.