The Massachusetts spy, and Worcester County advertiser. [volume] ([Worcester, Mass.]) 1825-1831, 1828-08-13
From the London Mechanics Magazine.

MosPHERIC PRESSURE. Sir,-In recent num-
Der of the Salisbury and Winchester Journal,
was the following curious fact | should be glad
to see it satisfactorily explained in your pages.
Z" Cut couple of cards, each into circle of
about two inches in diameter. Perforate one of
these at the centre, and fix it on the top of
tube,-say a common quill. Make the other
card ever so little concave, and place it over
the first, the orifice of the tube being thus direct
iy under, and almost in contact with the upper
concave card. Try to blow off the upper card :;
you viii find it impossible
A similar fact has lately occupied my atten-
ton, which | consider more unaecountable than
the preceding one.
Take the bottom pieces of two thin wooden
pill-boxes of the same diameter Perforate one
OF these in the centre, and insert the end of
quill Gas before.) On the other drop little
sealing wax in three or four places, at equal
distances, near the edge. Form the wax into
little elevations about quarter of an inch high,
so that they may all touch the other piece, when
placed on it. Then hold the piece with the wax
on it against the other ;--on blowing through
the quill, and letting go the under piece, it will
not fall off, but remain firm as long as you can
continue blowing. Pins stuck through the piece
will do, if they are firm, well as the points of
wax.
The cause of this phenomenon has been fully
investigated and explained by NJ. Hachette, of
whose papers on the subject the following abb
stract is given.
The first silnplifcation of NJ Hachette was to
make the nozzle of pair of double chamber
bellows terminate in the middle of fiat plate :;
he found that when the bellows were worked,
effects were produced opposite the Jet of air, of
the kind described by NJ. Desormes; namely,
that disks of card, and other substances, were
drawn towards the aperture, against the direc-
Mt hn ha hat ha
described this experiment, he also announced
his having produced the same effects by using
stream of water instead of stream Of air
The apparatus was still further simplified, so
as to make stream of air from the mouth sufii-
cient to produce the effect
Nj. Hachette, in explanation of these expert
ments, says The air is pushed from the mouth
of the tube, towards the oriGce of the plate it
strikes the part of the disk opposed to this orice
and the mean pressure on that part is greater
than the pressure of the atmosphere The
blown air then takes place of that between the
plate and the disk opposed to it; it moves in
this interval with velocity decreasing from
the edges of the aperture; the elastic force of
this air decreases at the same time, go that its
mean pressure between the plate and the inner
face of the disk becomes less than the atmos-
pheric pressure; and as this last pressure is
exerted on the whole external face of the disk,
this disk being subject, at one and the same
time, to the two contrary pressures on its OPP
posing faces, obeys the greater, and is pushed
towards the plate. 1t is not necessary that the
disk should be near the orifice of the tube.
DEATH INsTIECTIvELY CouETRRFEITED. No
| beast of prey ever more patiently or more sue
cesStu!lY practsed systematic stIatagem for TAX
ing his victims at unawares, than several sorts
OF insects employ TO deceive or elude their enc
mics, by counterfeiting death. This is a very
common device among spiders, moths and vari-
Gus sorts of beetles, and is varied according to
the forms and habits Of the species The moths.
CASUALLY the small tine@ and tortrces,) when
they think themselves in danger, draw their
antenne, as well as their wings, close to their
body, and in this state they may be tossed about
without manifesting the smallest sign of life or
motion. The same circumstance is recorded
by every writer on the subject, with respect to
beetles. The small gray beetle. so well known
for making pin-holes in old furniture, is one of
the most common instances, and is, or may be,
familiar to every person who chooses to observe
its singular habits, as it is to be found in almost
every house. This little beetle has received
from naturalists the title of pertinax, from it's
pertinacity in counterfeitng death. De Greer,
the celebrated Swedish entomelogist, informs
US, that it equals if does not exceed, the heroic
hrmness Of the American savages in bearing
| torture; for, he says, you may MAIN them, pull
them limb from limb, and even roast them over
| slow fire, without making them move Joint,
or exhibit the slightest symptoms of suffering
pain. Spiders, also, may be similarly tortured
and manned, as Smeliie has remarked, when
\ they assume the attitude Of counterfeting death.
1t is very common, also, with the little beetles,
called hyrrhi by entolnologists, TO draw in their
feet and their antenne, so as to give themsC. es
the appearance of a pill, from which indeed,
they take the name of plll-beetes. 1t is remark
| ed, IN Kirby and Spence Introduction, that the
| black purplish shining beetle, which abounds on
every road deceives Its enemies, the rocks, by
setting out its legs as stiffly as if it were made
of iron-wire, and remaining perfectly motionless
and as the rocks win only eat them alive, this
stratagem is an effectual protection. Some OF
our physiological readers might be apt to sup
pose that this stimulation of the death, so sue
cessfully made and persisted in, might be the
consequence of strong CONFUSION caused by
fear but it is fatal to this explanation, that the
insect, which is practising what appears to us
to be instructive device, makes Oft with all speed
the instant the object of alarm is removed !;
whereas, if it were convulsive sttitude, the
animal could not resume its movement at pleas
ure.-ForeigR Journal.
The BLUE YARN STOCKINGS. When DR.. B.
Franklin was received at the French Court as
American Minister, he felt some scruples of con-
science in complying with their fashions as to
dress. ." He hoped" he said to the minister,
'that as he was very plain man, and repre-
scented plain republican people, the king would
indulge his desire to appear at court in his usu-
al dress. Independent of this, the season of the
year (sad hey renders the change, from warm
yarn stockings to tine silk, somewhat danger
| GUS"
| The French minister made him bow, but
said that the fashion was too sacred thing fol
him to NEEDLE with, but he would do himself
the honor to mention it TO his majesty.
! The King smiled, and returned word thai
DIR. Franklin was welcome to appear at court il
any dress he pleased. In spite of that delicate