us
forms, has led M. Poncelet to this very important conclusion, namely,
that the friction in screws with square threads is to that of equal
screws with triangular threads, as 2.90 to 4.78, proving a very
important advantage of the former over the latter, relative to the loss
of power incurred in both by friction.--_Brande's Journal._

_Fulminating Powder._

According to M. Landgerbe, a mixture of two parts nitre, two parts
neutral carbonate of potash, one part of sulphur, and six parts of
common salt, all finely pulverized, makes a very powerful fulminating
powder. M. Landgerbe adopts the extraordinary error of supposing that
these preparations act with more force downwards than in any other
direction.--_Bull. Univ._

_Aurora Borealis._

An aurora borealis was seen from North End, Hampstead, near London, from
about seven o'clock until eleven, on the evening of Dec. 1. It generally
appeared as a light resembling twilight, but shifting about both to the
east and the west of north, and occasionally forming streams which
continued for several minutes, and extended from 30 to 40 degrees high.
The light on the horizon was not more than 12 or 15 degrees in
height.--_Brande's Journal._

_Paper Linen._

According to the Paris papers, a new invention, called _papier linge_,
has lately attracted much attention. It consists of a paper made closely
to resemble damask and other linen, not only to the eye, but even to the
touch. The articles are used for every purpose to which linen is
applicable, except those requiring much strength and durability. The
price is low, a napkin costs only five or six centimes (about a
halfpenny), and when dirty, they are taken back at half-price. A good
sized table-cloth sells for a franc, and a roll of paper with one or two
colours for papering rooms or for bed curtains, may be had for the same
price.

_Maturation of Wine._

M. de St. Vincent, of Havre, states, from his own experience of long
continuance, that when bottles containing wine are closed by tying a
piece of parchment or bladder over their mouths, instead of using corks
in the ordinary manner, the wine acquires, in a few weeks only, those
qualities which is only given by age in the ordinary way after many
years.--_Nouveau Jour, de Paris._

_Indications of Wholesomeness in Mushrooms._

Whenever a fungus is pleasant in flavour and odour, it may be considered
wholesome; if, on the contrary, it have an offensive smell, a