Evening star. [volume] (Washington, D.C.) 1854-1972, 1889-08-03

taste for matters scientific. At any time Of the
day just now you may see gathered about an
opticians window q crowd OF people who ca
Rerly watch the operation Of two simple in
struments, each Of which illustrates what might
be called the action of suns ray az work. One
OF these contrivances is q circular disk twelve
inches in diameter, divided by spoke-like lines
into several differentiated parts, each of which
Is tinted some color Of the raiIbow-blue, red,
green, yellow, and the resin order as they
appear in the solar spectrum. BY the action
OF a small electro motor the disk is made to
whirl around at intervals, the result being that
to the eye of the observer its surface appears
perfectly white. This of course, Is intended
to illustrate the fact that the white light of the
sun is made up Of all the colors of the rainbow
mixed together in due proportion.
THE RADIoMErER.
The second instrument referred to is a
''radiometer," the most important part Of
which is four tiny copper plates revolving after
The manner of weather vane on pivot. The
the suns rays coming through the show win
dow, and accomplish their little performance
within glass-surroundedv vacuum, which offers
no resistance worth mentioning to the move
ment OF the apparatus. On one side each Of
the little plates is painted black, 80 as to absorb
the light; on the other side it is brightly sill
vered, in order to reflect much possible.
Thus the energy, of which the light and the
accompanying heat are merely notifications,
is exerted on the black surfaces, and being shed
on the bright surface, the pivoted plates are
made to revolve. Even in moderately well
lighted room they will keep going all the day
time, while in the sun of noon they whirl
around like everything, as if impelled by some
invisible and mysterious force. Philosophers
have thought that like principles might be use
surface exposed to the sun for the running of
machinery; but SO far the notion has exhibited
no more promise of being successfully utilized
than the scheme for extracting gas from water
wherewith to keep the earth agoing.
NIGHT AMATEUR PHOTOGRAPHER.
There is an amateur Photographic crank here
in town who has developed morbid passion
for most unusual pastime. II his identity
were ascertained-up to date it is a mystery
he would be apt to suffer from various kicks
and other unpleasant things inflicted by per.
sons who have undergone annoyance at his
hands.
The Charles river at this season
trvs.pg 'n Mace year f1Uoste
who paddle about on the calm waters after
shutdown and spoon and spoon and spoon until
| the very fishes come up to the surface and
gasp for breath. Naturally, the dark Of the
| moon is considered the most appropriate time
for these amatory pursuits, and it is at such
| periods of lunar observation that the cranl
photographer above referred to gets in hi
| highly reprehensible work. Armed with
camera he paddles light canoe silently abou
over the still surface until he finds himself un
| perceived in the neighborhood of some small
craft, the suspicious immobility Of which be-
trays the presence Of
CUPID AT THE HELM.
| Then, without making tho slightest noise
he trains his instrument upon d unconsciou
victims, springs little magnes' flash light
and jerks simultaneously sp, ing that expose
a dry plate for fraction of u second. This
at any rate, is supposed to be his method
though the astonishing swiftness with which
he skips away down stream after performing
an operation of the sort has thus far pre-
cluded all possibility of investigation. TIL,
outrage has been perpetrated SO many time
that the owner of the canoe must now have
quite gallery of lovers afioat, in goodness
knows how many Photographic phases of anna
tory progress, all ready for exhibition at 81
much head to the thousands of curious PEG
pie who would undoubtedly be willing to pa,
literally for view Of the collection. An(
meanwhile it appears that engaged or court
| ing" couples who 60 out in boats to spoon upol
the Charles are rapidly becoming fewer. owing
to the fear of being took" unawares by THU
scamp with the magnesium light.
| RENE RACINE