The Saint Paul globe., 1900-11-11
sequently the direction, Of the I.ecnid


Some of the photograph appliances to
be used-always supposing the swarm re-
appears-have been especially devised for
the occasion. The most remarkable. per-
maps, IS a swinging camera, for securing
stationary images of the Leonids. 1t Is
ike the swing of a pendulum--in, state
OF balance at either end; moving faster,
comparatively than the shooting star at
the middle, but at some point between,
on the rise or the fall, exactly corre-
spending to the, velocity of the object
which it is all this time photographic.
Besides getting the image at rest IN this
way, 1t will be easily possible to calculate
the speed Of the meteor by ascertaining
the position of the camera in its swing
when that image was secured.
Another interesting instrument Is fitted
with prisms to photograph the spectra Of
the LeonidS, from which II will be posi-
BILE to learn their composition. The only
spectrum Of a shooting star ever secured
by photography was obtained at the Har-
ward station at Arequipa four years ago.
and shows by it's lines the presence of
hydrogen. Still another Photographic In
strument has a rotating disc over the
aperture. revolving thirty times a second.
In the disc is hole which, passing over
the aperture, records the path of the
meteor in "a series of dots. Any differ
ence In the distance between the dots
would give an Indication of a difference
IN the rate Of movement of the meteor.
The preparations at the Harvard ObSer-
yatory last year were on very extensive
scale, and covered a number OF stations
three in the vicinity Of Providence. H. l..
and two, including the Observatory itself,
near Boston. The plan for the work in
Cambridge was an admirable example Of
the way astronomers are able to system
atiZe difficult and complicated observa-
uons, and will be followed, if opportunity
offers, next week. Aside from those in
charge of the photoeraphing, the staff
viii be divided into counters time-k keep
erS, recorders, cloud-o observers Ito note
interruption In the observations) and
draughtSmen.
The matter OF time Is, Of course, most
important. A gong will strike automati-
cally every ten minutes, so as to afford a
constant check on the observations. At
the beginning Of observation the counters
will have stationed themselves to watch
the portion of the sky containing the con-
steIlation Of the Lion, and count the
meteors as they appear, while the time
keepers note the time of each as exactly
as possfble-a difficult undertaking when
1t is remembered that the mateors may
| possibly fall at the rate of over fifty @
minute. The record Will serve to iden-
tify ALL or at least great many, Of the
lis 'lCOAS ny IL serial HuDlD3r ana lQe time
recorded.
The general observers will look for
special features, like the magnitude. col
or, whether the stars explode or not and
whether trail appears. A general OBJ
server, for example. may note that the
ll2th meteor marked by the counter was
yellow and left a trail lasting ten sec
oEds, and that its path was from near
! some standard star to another standard
In Il lot ~.
the observation sheets Of the other OBJ
servers. With each general observer
VIII be recorder, to note according to a
code the phenomena which he announces.
The draughtsmen will be supplied with
maps Of the region around the constella-
ton Leo, and they will draw the path as
well as possible of each notable meteor.
the direction and line of the 10TH
meteor, for instance. its brightness and
the character of its trail, are useful facts.
The matter of brightness Tecessitate the
quickest obserNa ton. which offers, how
ever, no special difficulty when one has
nothing else to attend to. The scale
adopted df one may go into technical
details for momenO Is to assign A mag
nitude Of minus to a meteor a little
brighter than Sirius or Jupiter; 0. If
equal tosCapella; 2, If equal to Gamma
Leonis, the bright star in the blade of
the Sickle, which stands out clearest in
the constellation Leo; 4, if equal to Mu
Leonis, the second next star to Gamma
in the Sickle; 5, to faint meteors gem
orally.
A year. ago the Harvard Observatory
asked for the cooperation of observers
all over@ the world-not only astrono-
mers, but Intelligent laymen everywhere
and full circular of rules to govern
such observers was sent out by the Uni
Verslty. The most Important part of the
circular Is as follows:
The most important time for observa-
ton is from midnight until dawn, as com
parauVely few meteors are expected
earlier. Observations are particularly
needed at hours when they cannot be
made at the obserVatories of Europe and
America. In general, the time REQUIRED
for ter or more meteors to appear in the
region covered by~1ho-a ecohnpanyIng map
should be recsrTid1, THIS observation
should be repeated every hour or half
hour. II the meteors are too numerous
| to count all those appearing upon +ha
map, the observer SHOULD confine his at
tentiOn exclusively to some small region
| such as that included between the sta rs
| Mu Ursae Majoris, 40 Lyncis, and Della
ana Alpha Leonis. If the meteors occur
but seldom, one every five minutes, for
instance, the time and class of each me-
| teor should be recorded. Also note the
| time during which the sky was watched
| ana no meteors seen, and the time dur-
| ing which that portion of the sky wa 9
| obscured by clouds. Passing clouds or
haze, during the time of observation
should also be recorded. The date should
be the astronomical day, beginning AT
! noon; that is, the date OF early rnorning
| observations should be that of the nre-
ceding evening. Specify what time is
used, as Greenwich, Standard or Local
! time. When a meteor bursts make y
second obserVa tion Of its light and. color
| and, when it leaves a trail. record tbo
! motion of the latter by cfarting tho
I ne1ghborfng stars and sketching it's most
! ton among them at short intervals lu,tfI
! 1t disappears, noting the time of each
! observation. If the path of meteor ts
surely curved, record it carefully upon
the map
Photographs may be taken firs+ br
! leaving the camera at rest. when the
images of the stars will trail over tbe
plate and appear as lines or, secondly at
! tachlng the camera to an equatorial taIa-
I scope moved by clockwork, when a chs -,
/ OF the sky will be formed, in which 49,
stars will appear as points A raDid-rec
/ tlInear lens is to be preferred in the frs,
! case, wide-ang!e lens in the second
! The full aperture should be used and ac
! large Plate as can be covered Thf
most rapid plates are best for this work
! they should be changed once an hour apf
/ the exact times of starting and stoppins
recorded. Care should be taken to stiffer