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.

Our readers will recollect an illustrated description of an universal
wood-working machine, published on page 79, Vol. XIII. of the
SCIENTIFIC AMERICAN. The machine herewith illustrated is manufactured
by the same firm, and is a valuable addition to