Crawford avalanche. (Grayling, Mich.) 1879-19??, 1893-03-16

Their Extensive Use in London, Paris
Vienna and Berlin.

In an article on Progress IN Pneu'
matte Transmission, In the Engineering
Magazine. William Allen Smith gives tho
following facts regarding the use OF
pneumatic tubes In Europe.
Pneumatic tubes for local transmits
sion of kilograms are now used IN all tho
principal cities OF Great Britain. AT
present about fifty miles Of such tubes
are in operation, requiring an aggregate
of 400 horse power, and transmitting
daily average of over 105, 900 messages,
or over 80, 900, 900 annually; more than
half of these in London. Tho
lengths of tubes vary greatly; the
average length Is about e5O
yards; the greatest single length In
London is 3, 902 yards. The tubes areo OF
lead, laid in cast-iron pipes, for protec-
ton, and are usually OF two ana one
quarter inches inner diameter; some tubes
of one and one-half and some OF three
inches inner diameter are used. AS
general rule, with the same air pressure
and diameter of tube, the speed varies
inversely as the length of tube. In tubes
not over mile long the usual average
speed is twenty-five to thirty miles an
hour. The carriers are OF gutta -percna,
covered with felt, with buffer nt the
front end, and an elastic band at the back
or open end to hold in the messages. An
ordinary carrier weighing two and three
quarter ounces holds dozen messages.
The marked success of the British
pneumatic service led to the adoption OF
similar systems in Paris, Vienna and
Berlin. The pneumatic system of Paris
was put into operation in 1866, and has
grown steadily, so that to-day in Paris
tubes are used almost Exclusively for
transmission of local kilograms and letters
demanding quick delivery. A small
stamped envelope. the petit bleu, costing
so ceatimes, or 10 cents, is used for the
message, which, dropped into a special
post-box, is delivered anywhere in Paris
within an hour, often in 25 minutes.
In Vienna the ''tube-post' was estab-
lished in March, 1875. The nine dis
tricts of the city are connected with a
central station. The ''tube mail' IS
dropped into special post boxes, col
lected every half hour. forwarded to the
central station and distributed. Pneu-
matte envelopes cost Is kreutzers about
6 cents), ordinary letters 3 kreu'zers.
1.-THE letters" are delivered within one
hour after mailing The Vienna system
consists of main circuit of 534 miles,
with three branch lines; total length, 7.2
miles.
In Berlin the Prussian postal authori-
ties began in 1852 discussion OF measures
of relief for the ovcrcrowded local tele-
graph system, and pneumatic line was
opened in 1861 between the Central Tel
egraph station and the Exchange build
ing. The beginning of the present ex-
tensive ''tube post" at Berlin dates from
1876, since which time it has been en-
larged, until there are now over % miles
of tube-line in the city with 80 stations.
Tube letters" are to-day delivered in
Berlin more quickly than kilograms at
cost equal to u cents, and tube post
cards" at CT cents The tubes in Berlin
: arc of wrought iron, and have an inner
! diameter of 6J NM, equal to 2.55 inches
The system is operated by eight steam
engines, aggregating only 1913 horse
, power.
, The British tube lines are laid on the
!. radial system; that is, the different lines
! radiate from centres to the various
|. branch stations to be reached. In Paris
! Vienna, and originally in Berlin the vari
GUS stations were connected by a series
, OF poIygons, around which the motion
is uniformly in the same direction. a
study of the two systems, for connection
: of given number of stations under or
q binary conditions, leads to the following
q comparative results:
/. The polygonal system will require
, about 30 per cent. more tube length thar
the radial.
q II. The polygonal system allows mucl
! greater use of compressed air for for
3 warding, as the passage around the poly
y gous is always in the same direction
: Rarefied air need be used only for the re
A turn passage in the links connecting tn
: polygons, or for the return from a single
. isolated station. In the radial system
: rarefied air is used for half the passages
= This shows greater economy in workin
- for the polygonal system.
III. The time consumed in communi
= eating between stations is less in tn
- radial than in the polygonal system. |
~ the latter, time is frequently lost b
: sending message almost completed
around the polygon.