The true northerner. [volume] (Paw Paw, Mich.) 1855-1920, 1872-06-14
Curious and Scientific.

Measuring The Velocity Of Rotafion.-
Prot. A. 4. Dolbear suggests, in the
american Journal Of Science, y simple
and effective method of determining
the velocity of rotation of wheels and
shafts. Upon the face or upon the
periphery of the rotation object, he fas-
tens smoked paper, and this he touches
with point Of rubber which is attached
TO one branch of vibrating tuning
fork, having known rate of vibration.
The fork is to be so held that the direc-
ton of its vibrations will be at right
angles to the line of motion of the shaft.
By counting the number of fluctuations
made on a given extent of the smok ed
paper, the speed of rotation is at once
indicated. Thus, if the fork makes 100
vibrations in second, and one vibrs-
ton is recorded on the smoked paper
in space covering oiSs.half of the cir
cumference of the wheel or shaft, or
two vibrations within the entire circum.
ference, it is evident that the rate of
rotation is fifty revolutions per second.
By this simple and easy method, the
velocity of rotation OF gryoscope disks
and all kinds of shafts and wheels may
be readily ascertained.
Why Lace Is Costly.-The finest speci.
men of Brussels lace is so complicated
as to require the labor of seven persons
on one piece, and each operative is EN-
ployed at distinct features of the work.
The thread used is of exquisite fine
ness, which is spun in dark, under
ground rooms, where it is sufficiently
moist to prevent the thread from sep
arating. 1t is so delicate as scarcely TO
be seen, and the room is so arranged
that all the light admitted shall fall
upon the work. 1t is such material that
renders the genuine Brussels ground so
costly. On piece of Valenciennes
not two inches wide, from two to three
hundred bobbins are sometimes used
and for a larger width as many as eight
hundred on the same pillow.
Porous Filters.-In the course of an
examination Of filters, at the instance
of the British Medical Journal, Professor
Wanklyn has had proof that filtration
through beds of porous materials in
cludes very powerful chemical action,
albuminoid matter being instantly re-
solved into ammonia and other products
by the action of the filters, which, in.
deed, behaves in this respect like a
boiling solution Of permanganate OF
potash. A good filter is a sanitary en-
CINE OF great power.
Velocity Of Somd-Mr. J. E. Stone
astronomer royal at the Cape of Good
Hope, has experimental on the velocity
of sound from the discharges of the
o'clock signal-gun at the castle, the two
observers being l4,S0S feet apart, and
communicating with each other by tele
graph. The result indicates velocity
of l,090.6 feet per second at freezing
temperature.
Habits Of Dvcks.-M. Trevers says that
the blue duck of New Zealand does not
exhibit solicitude for the safety of it,
young like other ducks. DR.. Hector
extends this characteristic absence o.
fear to most of the native New Zealand
birds. Darwinians account for these
facts by supposing the arrival of man
on the islands to be so recent that in
stinctive fear has not been developed.
Woody Fiber Dissolved. - Ligniuc, OF
cellulose, the chemical constituent Of
woody fiber, has been regarded unit
recently as insoluble. Our clothing
wears away, but no amount of washing
leaves any portion of its solution. i
has, however, been found that the fiuic
"cupro ammonium is ready solvent
SO that the old problem of maxim.
planks out of sawdust is no longer
mere jest.
Fires From Heat PpeS.-Wherever iror
pipes are employed for con, eying an,
medium, such as smoke, hot air, steam
or hot water, they should not be allowed
to poss through woodwork unless pro
tected by an earthen crock. The iroi
rust may be deoxidized by heat, anC
upon reoxidizng it often becomes red
hot. Many fires have occurred from
this cause.
Another Great Inve,ation.-The invento
of hydrate of chloral has introduced
new organic compound called croton
chloral, by which, it is claimed, tn,
head may be rendered insensible Will,
the other parts of the body remain un
affected. 1t promises to produce all tn,
good effects of hydrate of chloral, with
out any drawbacks.
Sponge Paper.-Sponge paper, mad,
by adding finely divided sponge to pa
per pulp, is used in France for dressin,
wounds. 1t absorbs water readily, ant
retains moisture for long time, and i
applicable in the arts and sciences.
"A paste made of wheat flour or corr
starch is more satisfactory than an,
gum mucilage for scrap books. A it'll,
spirits of camphor or diluted carboli
acid will preserve it for a considerable
time from molding or securing.
DIR. Blake, President of the Califor
MIA Academy of Sciences, considers tina
the most remarkable feature of the wa
tiers in the Yellowstone geysers, is tn
enormous amount of ammoniacal salt
which they contain.
Drowning OF an AerOnaut.