The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1869-10-28
POPULAR SCIENCE.

explosions Mr.. Henry Bessemer in a letter
addressed by him to the Times has suggested
O method of lighting coal mines which ap-
pears well worthy of careful attention Mr..
Bessemer has been lately engaged in investi-
eating the action of combustion under high
pressures, and the results which he has OBJ
tanned have led him to consider that lamps
in which the combustion goes on under pres
sure exceeding that of the atmosphere
might be advantageously employed for light
ing mines. Thus he states, for instance
that an iron box, having one side fitted with
O bull l's-eye, or formed of thick plate glass,
may be fitted with an ordinary gas-burner,
supplied with gas from a gasholder above
ground, and that the air to support combus-
tion may be supplied to this box by a suitable
pipe at a pressure Of, say, one pound per
square inch above the pressure of the air i'll
the mine, a small hole being left at the top of
the lamp for the escape of the products of
combustion. Under such circumstances not
only would the light produced by the COM
bustion of the gas be intensified, but the
pressure within the lamp being in excess of
the surrounding atmosphere, the latter would
be prevented from entering, and conse-
quently even if an explosive mixture existed
in the mine, it would be perfectly safe from
ignition.
Such is Mr.. Bessemer's plan, and an adj
mirably simple plan it is. BY the aid of a
series of brilliant lights, such as he proposes,
the galleries of mines may, as he SAYS, 'be
lighted like a workshop, and there is really
no good reason why this should not be done
The supply of air and gas, under suitable
pressure, presents no practical difficulty, and
by the aid of suitable reilectors, one powerful
lamp, such as described, would be enabled to
give O good light for some considerable dis
lance around it. BY the aid of easily con-
trived arrangements, also, some of the lamps
| l., -. ,l,.., l..
required, but in such a case care would of
course have to be taken to protect the glasses
from accidental fracture. Mr.. Bessemer
states that he is convinced that the thorough
lighting of coalpit, and its ventilation so as
to insure health and safety to the miners, are
purely a question of S. d. - Van Nos
hdnd'S Magazine.
oxygen Liberated bv Light.
The starting-point Of organic constructions
is the chemistry of the leaf, by which car
bonic acid is decomposed and oxygen set
free. This effect has been supposed to take
place only under the influence of light, but
the conditions are not so clearly defined as to
make further research unnecessary.
M. Bousingalt, of France, has made this
subject matter of investigation, and has
lately presented the results Of new series of
/ studies upon it. His question was, Does de-
| composition of carbonic acid, by leaves, take
| place in diffused light? If once commenced,
| does it 60 on in darkness? His mode of in
quiry was based upon the fact that phospho-
rus does not shine in an atmosphere of car
bonic acid, but becomes fiuorescent as soon
as a little oxygen is mixed with it. Hav-
| ing ascertained that phosphorus is not
| hurtful to plants when placed near them;
he puts leaves of laurel in vase of carbonic
acid, containing also phosphorus, and exposed
it to the sun. Oxygen being liberated, the
| ,,1,, A11nracnnnf ho
vase is placed in darkness, the fuorescence
ceases after varying number OF seconds,
| and lasts the longer the smaller the surface
exposed by the phosphorus. This arises from
the phosphorus requiring certain time to
absorb all the oxygen engendered in the last
moments of exposure With sufficient sur
face of phosphorus the fuorescence ceases
instantaneously, from which it is inferred that
the process of liberating oxygen does not go
on in the dark, but only when subjected to
the motive force of light.
Sewing bv Springs.
The new French sewing machine invented
by the Misses Garcia and NJ Adam is driven
by series of six springs, each Of which is
doubled in order to prevent forced STOP
page in case of accident. The springs are
contained in barrels, disposed in pairs on
three horizontal shafts, placed in the case
which serves as table to the machine. The
|
which the springs are wound up, and forms
the stop-work of the whole series of springs;
the spring which it encloses is fixed to
it by its external extremity, while the
inside end gives the impulsion to the
shaft on which this first barrel is
mounted The impulsion given by the first
spring is communicated to the whole six by q
series of tooth-wheels. The machine, thus
wound up and set a-going, takes about an
hour to run out, making from four hundred
; usual rate of speed maintained by a skilled
: workwoman. The springs once run out, can
be wound up again in the short space of one
minute and half so that the loss of time il
this operation is scarcely percephble The
fy-wheel, which regulates the speed of the
machine, is of great strength, and easily
worked even by unsklled hands. Altogether
, the machine is very interesting and ingenious
We only hope that the curtailment of labo
) which it promises will prove to be a reality.
Speed and Power of Locomotives.
The speed of an engine depends on tn,
rapidity with which its boiler can generals
/ steam. One cylinder full is required for eacl
stroke of each piston Each double strol1
corresponds to one revolution of the driving
wheels. and to the propulsion of the engn
) through space equal to their circumference
: Wheels seven feet in diameter pass owe
: twenty-five feet in each complete re
, volution. To produce speed o
g seventy-fve miles an hour they must revolv
A exactly five times in second; and to eifec
c this revolution, each piston must make dou
! BILE that number of strokes in that time, an
= consume ten cylinderfuls of steam. Tn