The Princeton union., 1891-04-23
SCIENCE AND PROGRESS.
CURIOUS INFORMATloNF FOR EN-
CURING MINDS.
How Celluloid Is Made--The Nee
die Does Not Mark tre True
North--The Smallest Steam
Engine--Hypnotism In
Dentistry.
/ It ls a Novelty IN Launches.

AN0Va1 O1l1CldlS afe WaCcnlng With In
terest the result OF number Of ex-
periments by the English Government
with the electrical launch. The first
craft built for the government was
launched into the Thames from the
yard OF her builders. The pinnace is
called the Electric, and, according to
her builders, is certain to- do away
with the bad-smelling, dirty noisy and
bulky steam engines wh1cn are to be
found in all the house boats on the
rivers of the civilized world. saa ~. n,
The new craft is open, 48 g. feet long
and 8 feet OF beam. She is to- be used
Tor the conveyance of troops between
the dock yards of Chatham and Sheer
ness, and is able to transport with
perfect comfort forty soldiers. The
electrical accumulators are concealed
beneath the seats: the motor and pro-
Peller working with singular ease.
There is little Or no vibration. The
vessels speed is about ten miles an
hour: She can be got in readiness for
a trip at a minutes notice, NO engineer
being required, the emost inexperienced
person being able to takecharge other.
The- craft can run for ten consecutive
hours on single charge of electricity.
Since the vessel was launched the
builders have been flooded with or
ders;;the last coming from the Mexican
Government. Baron Rothschild is al
SO to have one and all the prominent
boatmen of the river intend to list
their names as purchasers Of an elec-
trio pleasure boat. An American
builder, learning of the success of the
Electric, has decided to start a. de-
partment forthe sole construction of
the craft. He thinks that in two
years time the Harlem and Hudson
rivers and the bays will be- crowded
with electric launches and that all the
big steam yachtsmen will get one or
more boats as tenders.
How Celluloid is Made.
While everybody has heard of or seen
or used celluloid, only a few know
what it is composed of or how it is
made. A roll of paper is slowly un-
wound, and at the same time satura-
ted with a mixture of five parts of
sulphuric acid, which falls upon the
paper in fine spray. This changes
the cellulose of the paper into, propy-
lin gun-cotton. The excess of the
acid having been expelled by pres
sure the paper is washed with plenty
| OF water until traces of the acid have
! been removed. It is then reduced to
| a pulp and passes to the bleaching
trough. Most Of the water having
| been got rid of by means Of a astrainer,
| the pulp is mixed with twenty to
| forty per cent. ofits weight in camphor,
and the mixture is thoroughly tritu-
rated under millstones The neces-
sary coloring having been added in
the form of powder, a second mixing
and grindingfollows The finely divid-
ed pulp is then spread out in. thin lay
ers on slabs, and from twenty to
twenty-five layers are placed in hy-
draulic press, separated from one an
other by sheets Of blotting paper, and
are subject to a pressure of $50 at
mospheres, until all traces of mois-
ture have disappeared. The matter
is then passed between rollers heated
to 14O0 to 1902 f., whence it issues
in the form of elastic sheets.-The
Colliery Engineer.
The Needle Does Not Mark the True
North.
The old saying, '"True as the heddle
to the pole,' is quite misleading, be-
cause three people in five who, use it
are thinking of the North Pole,. while
the fact is that the termini of the
earth's axis are not coincident with
the magnetic poles. It was of great
Importance to navigators in northern
latitudes to determine the exact posi-
tion Of the north magnetic. pole in or
der to make the needle q perfectly
trustworthy guide. One day nearly
sixty years ago, while the famous DO
lar traveller, Sir John Ross, was sledg-
ing over the ice hummocks north Of
this continent, he found a place on the
western shore OF Boothia Felix, where
the dipping needle wholly lost it's di-
rectlve power and stood with
in. one minute OF the verti-
cal. This discovery enabled Gree
! w., at Lady Franklin bay, when
he found his needle pointing nearly
southwest, to determined the true
north by a few minutes calculation.
The position of the south magnetic
pole has also been Approximately
determined, and not a sea-, captain
sails the ocean to-day who is not
! greatly indebted to these discoveries
These magnetic poles slowly move
back and forth across the polar area.
They have probably changed their
position since they We're found, and
scientific men q while ago were urging
the Importance of sending out expedi-
tlons to relocate ethem.-Goldthwa
Geographical Magazine. .#s
4 Flies Of Long Ago.
The chief supplies Of amber, which is
q fossil gum that exuded from pines
and other trees perhaps two million
years ago. came from the bed OF the
Baltic sea in northern Prussia. MANY
OF the Jumps OF amber contain insects
OF various kinds, leaves, parts Of