New-York tribune., 1874-07-23

The snre in the above diagram are july respect
~ rcy noted for and extending from the
position including Aruru' Gesry to the zenith and on
planets Jupiter indicated BY their usual Astronomical
characters
In another respect the tail of Cogga's comet fur
oishes the means for an unusual for approaches
so near us that II visible either in the northern or the
southern hemisphere within week from this tme and,
IL carefully observed its form and position In space can
De determined with accuracy. The position Of the por
ton OF the tail above horizon, from July 20 to July
"a inclusive are shown in the above diagram computed
Tor midnight On the oath the tail is prolonged further
than on the previous days to represent the portion
near the zenith which, in consequence OF its pointing
directly from us, will be likely TO be more easily seen
than the portion to us although fear 1t will be
an invisible something"
Prof Pcirce IN his computations, assumed for the
front edge OF the tail which in that was most easily
observed an excess Of repusive force and half
times the force Of gravitaton. In this case Is neces
sary 10 determine the center OF the tall therefore
carefully computed the position OF the front edge by his
formula thence dedueed the position OF the center from
NV own observations Of Its comparative width, aud
from the line OF the center computed the two visible
edges Upon examination OF Prof Perce's results was
led 10 assume repusive force exactly equal to and
replacing gravitation the primary law for the center
OF the tail and found tna the line thus obtained agreed
with that obtained by tho former crcuitous process
and was also confirmed by observation.
This tends show that under certain conditions the
matter forming comets tale has It's polarity changed
converting attraction into equal repulsiOn. Matter i'm
prsoned within the substance Of the comet, having
opposite polarity and aterward freed and beginning to
move under the law Of repusion, would equally explain
IT, This leads to the question, May there not be polar
iy in all materl For instance, IN the intensely heated
condition OF jupiter and the rcpeant matter
exist, winch, couuterbalancing a portion OF the at
traciiye matter would diminish their apparent mass"
There are two formidable objections 10 this idea first
that the matter repeed fast could be set free
would rs of Ike a comets tall reducing the bulk and
Increasing the apparent density second that If the
rolarty ef the same could be changed asr0no-
1uers would be at in the computation OF perurba-
tons TIE first Of these objections is perhaps met by
fact in the history OF a comet. When first seen the
form Is spherical, showing internal attraction. When 1t
approaches the sun, the form first becomes ellptica
showing that the replsion OF the sun begins TO operate
while The comet itself s continues to attract the
matter and by It's superior force retains 1t within Its
influence Perhaps this may be the condition OF
ton Of the matter composing the larger planets aud the
sun.
when the comet comes the SUM- the matter not
onIy repee from the SUD. but repeled from the nu-
elena of the comet directly toward the sun. The law
NJ these changes remains entirely unknown There Is
pbepomepon especially observed In the case OF Dohas
comet which indicates still another law. sueamers
were seen TO shoot forth from the convex SIDE OF 'he w
10 great length and II would seem as IL az every
aarmaton Of a new enyeloD In the coma. thsr' WAS