New-York tribune., 1901-03-17
SIGNALLING TO .uiRN.
WHAT SIR ROBERT RAIL THINKS OF THE
POSSIBILITY.
From The London Globe.

From The London Globe.
In The PAN Mall Marazne" Sir Robert Ua!
sprays some cold facts on tn" Wild theories
about tn possibility Of signalling :" Mars. Even
urdor the very most favorable circumstances.
which can. IN fact. never hc quite realized tho
distance between the earth and Mars cannot h.
under :",5'ahotp miles. 1t may. cccd. be said
that 3IH'I"n miles is nearly the lowest value
10 which the distance can decline under the
present condition of The orbits. and this can
on.E occur Mhen me opposition takes i!a'' 'i"S'
to August -. We may mention that when tho
first satellite of Mars discovered 10y Pro
fessor Han. on August Ia. 1871. the d.stance
from the nlanet to the earth was 3G.Wn.WD
miles. which was still TlIlli"n miles over Ii"
love 81 distance 10 which II could sink with tho
concurrence. Of the best conditions. The qucS-
tion then arises to the KIND ol signal which
could he transmitted across "A distance of b
GltHN mics
\ building bg 81. PauTs Cathedral on
our satellite would about represent the size of
. the smallest visible object on the moon: W."
therefor" infer t3at a bndns would havr t. h-
ere hundred and fifty times as long and one
! hundred and fifty times as broad 81. Haul's
to ht dlSC'IHlhe as the smallest point Mars
( Assuming that thrr, were inhabitants On Mars
VII" were dcsrOus Of making signals Ia the
earth by TIE waving OF Il flag that flag would
/ hardly be distinct enough for such Il IurpuSc
unless it were at least ten times as long as the
smallest visible point, ana he'd breadth in pro-
port~'r. We are thus lea TO the c"nc,us that
flag, say. some three hundred miles long and
tWo hundred miles broad. perhaps about as
large ireland. would be necessary for the
purpose. II we could imagine a flag Of these
cred miles long. and if the Martians awaited
themselves Of the next fave rahle oppositi0n say
II l!Ht', 10 make arrangements for waving this
colossal iaG to and fro, and if some of our most
ski'fui astronomers. provided with III, very
largest and most perfect telescopes, and STU
ated on the lOftitst mountains on which uhscr-
VatOries have been placed. were to he STUDYING
the surface Of Mars, they might, | grant, per
cslVe the waving Cf the flag. and might possibly
be abl" to receive certain indications thcrefrom
Let us suppose that me sigma ling power Of
wireless telegTaphy had been advanced 10 such
a perfection that it possible To transmit a
signal across distance of eight thousand miles
that is to say, across "A distance equal to the
diameter of the earth. think il Will be adj
mitted that this is very liberal suppuSittun.
The moon is, however, AZ a distGrce of about
thirty times the carth's diameter and there fore
even surprising that Marconis waves could he
sent across the earths diamct II. yet to lac APP
preciable IT the distance of the moon. which is
thirty times greater. the intensity of thos- waves
would have to be not merely thirty times. but
thirty times thirty-that is the efficiency must
be nine hundred times great ] have sup
posed. In other words even if the whole earth
brought within the domain of wireless
teegraphy, the system would still have to he
improved nine hundred times much again
before the moon could also he brought within
the sphere of influence. And let apply
this reasoning to Mars. | have shown that at its
very closest approach Mars must still be some