Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1891-03-15
FLASH LIGHT PHOTOS
A Picture of a Soap Bubble in the
Act of Going to Pieces.
MEASURING TIE ACTINIC RAYS.
An Easily.Made Paste That Is Guaranteed
to Stick Anything.
LITTLE BITS Of SCIENCE GOSSIP
rpREpAREp FOR THE prspArcH.1

rPREPARED FOR THE prsPArcH.l
A ready method of measuring the amount
of actinic rays proceeding from any land
scape or object has for long time been
thing much desired by photographers, both
amateur and. professional. Many instru-
ments with this. view have been from time to
time brought out, but none Of them have
proved very satisfactory. The same may be
said of tables, which, although of great as
sistance in open landscape, have this draw
back, that. wherever the quality OF the light
is interfered with, as in forest scenery, deep
glens with overhanging trees, where the
very air appears to be green, the interior Of
churches, etc., where the light which enters
perhaps passes through colored glass. and
under similar conditions, the operator is
compelled to guess at the exposure after all.
An apparatus, just patented in England,
purposes not only to measure the intensity
of the rays OF light proceeding from any OBJ
ject. but also the quality OF the same. The
actinometer can easily be adjusted to plate
of any degree of speed by removing or
adding to the layers of tissue paper behind
the glass carrying the luminous paint used
in the process. In adjusting the actino-
meter any of the published tables of e1-
posure may be employed, or, better still, the
excellent little calculating machine for pho
tographic exposures, called the actinograph,
upon the invention of which much labor and
study was expended.
AT recent lecture before the Royal In
stitution, England. the lecturer, after re-
ferring to series of photographs OF animals
in motion which had been taken BY means
of movable shutter, said that rapidly oc-
curing phenomena might also be photo
graphed by the exposure of the lens to a
flash of magnesium light or to the electrical
spark. After stating that neither of these
flashes of light was absolutely instantaneous,
he proceeded to show their actual duration.
1t appears that a spark from Leyden jar
lasts less than one twenty y-fye-millIonth
part of second. Some idea may be formed
of such duration by considering that it is
nearly the same fraction of a second as one
second is of a year, as year contains rough
ly 25 900, 900 seconds. 1t was further shown
that soap film might be photographed in
the act OF breaking, but as this occupied
less than one-tenth of a second it was more
difficult to photograph than jets of liquid.
A dry shot would pass through soap
bubble without breaking it, but a shot
wetted with alcohol would break the film at
once. BY means of the dropping of weights
suspended from an electromagnetic, it was
possible to make the breaking of the film
and the fash of the spark simultaneous. and
thus photograph the film in the act of
breaking.
Among the many recent triumphs of pho
Biography were cited those in the medical field
and especially the invention which enables
the operator to photograph the throat and
a condenser condensing ten inches of solar
rays on to a one-Inch beam OF parallel rays
which brought down the question to the
matter of special camera. This was after
ward devised and the operation was per-
fected. A beam OF condensed light is now
reflected from glass bound on the operators
forehead into the patients mouth, and
tiny detective camera snaps the image of the
vocal chords in an instant.