Year: 1874

One or Unusual Magnitude and Brilliancy


Discovered by Prof. Langley.


The following interesting letter ap


pears in the Pittsburgh Gazette


During the past week spot has ap


peared on the sun of such unusual mag


nitude rs to have been visible to the


naked eye, and the occurrence is rare


enough to. attract attention, not only


from professional observers, but from


all who take an occasional interest in


such matters. Such large spots, it is


now well known, usually are visible, il


ut all, at certain definite periods, the


last time of their maximum having


passed some three years ago, and


though smaller ones are at nearly all


times seen with the telescope, it is more


than two years since any has presented


itself of the size of this, which, coming


so far out of season, offers spectacle


which is not likely to be repeated for


several years.


Perhaps, then, I may feel warranted


in inviting attention to the spot in


question, which can now be seen near


it is conspicuous with very little optical
aid, and is even visible with attention
through a smoked glass, looking like
small cloud ON the bri ghtness of the
western limb, behind which it will soon
disappear. Through great telescope
the spectacle is remarkable, over 40
smaller spots having united to form the
large one, whose length is somewhat
over $4,000 miles. Throughout this
extent the surface is broken up and
tossed into every form into which the
solar cyclones can distort the intensely
brilliant matter on which they are act.
ing. Curvilinear outlines (the traces
left by these whirlwinds) predominant,
but the intricacy and beauty of the
shapes are beyond comparison with any
of the cloud-forms of our own atmos-
phere, as they are also more definite in
outline. Some are crystalline in the
precision of their details but while
the crystalline patterns the frost traces
on our window. panes are not more
beautiful or definite, they cannot rival
the vivid splendor of these solar forms,
or bring up the impression we gain
when we observe that as vast as the real
dime nsions must be, they are shifting
and passing into new shapes from hour
to hour, and even visibly changing
while we gaze.


The interior Of a pudding furnace,
in which the white masses of iron are
seen, looking like melted snow, is in
miniature not wholly an unsatisfactory
type of one of these, and perhaps to a
Pittsburgh reader such compassion
will be as descriptive as any which can
II of l. l. l..
more points than one, for iron heated
to the point where it passes iuto glow
ing vapor is one of the prominent in
gradients in the clouds over and around
the spot. 1t is known that in our own
blast furnaces a comparatively small
quantity of the metal is vaporized out
Of every charge, and the results of an
estimate show that the total
quantity of iron thus dissipated in the
smoke of Pittsburgh furnaces reaches
an annual amount of over 5000 tons
m estimate which is startling, but
within the truth. With the help of
this result, and that of measurements
made at the Observatory, which shows
jhat the "spot" covers over 1000, ,OOO,-
700 square miles, we may try to con-
,eive the magnitude of the action which
ills with the vapor of iron and the
'arer metals such an area, every part of
which is necessarily at temperature
'bove any that the blast furnace can
'ival.


When we thus translate our micro
Metric measurements from degrees and
minutes into the more familiar ones of
niles and yards, we are met by num-
,ers so great that it does not seem pos
ible to realize the quantities they stand
or, and thus stated they never grow SO
amiliar as not to bring even to the
kind of new surprise with
ach verification. Reckoning in this
vay, we find that the minutest apparent
lot in all the complexity of forms /
ave alluded to-, must, for instance, be
arger in reality than the State of Penn !
ylvania to be Of the least visible mag ,
itude in our most powerful telescopes.
'hOugh all have even so briefly de. s
cribed cannot be seen in ordinary in
truments, the smallest will yet show
nough to make the "spot" an object 8
interest which some of your readers :
ill, in this holiday season, perhaps, ,
nd some inclination and leisure to en- ,
~. :