ent astronomers make the time of the passage of light from the
sun all the way from eleven to fourteen minutes, instead of Newton's
seven or eight. Busch reckons its velocity at one hundred and
sixty-seven thousand nine hundred and seventy-six miles; Draper one
hundred and ninety-two thousand; Struve two hundred and fifteen thousand
eight hundred and fifty-four. Wheatstone alleges that electric light
travels at the rate of two hundred and eighty-eight thousand miles a
second; but Frizeau's calculations and measurements give only one
hundred and sixty-seven thousand five hundred and twenty-eight for the
light of Oxygen and hydrogen.[353] Thus we have a variation of one
hundred and twenty thousand miles a second in all calculations of
sidereal distances. Humboldt tries to reconcile these differences by the
suggestion, that no one will deny, that lights of different magnetic or
electric processes may have different velocities; a fact which throws
all sidereal astronomy into inextricable confusion, and sets aside all
existing time tables on sidereal railroads.

They are no more agreed as to its composition after it reaches us than
as to its velocity. Newton taught that it consisted of seven colors;
Wallaston denies more than four; Brewster reduces the number to
three--red, yellow, and blue. Newton measures the yellow and violet, and
finds them as forty to eighty. Fraunhofer makes the proportion
twenty-seven to one hundred and nine. Wallaston's spectrum differs from
both. Field says, "No one has ventured to alter either estimate, and no
one who is familiar with the spectrum will put much faith in any
measurement of it, by whosoever and with what care soever made."[354] He
says white light is composed of five parts red, three yellow, and eight
blue; which differs wholly from Brewster, who gives it three parts red,
five yellow, and two of blue.

Equally wild are their calculations of the quantity of light emitted by
particular stars. Radeau calculates Vulcan's light at 2.25 that of
Mercury; Lias, from the same observations, at 7.36, nearly three times
as much.[355] Sir John Herschel calculates that _Alpha Centauri_ emits
more light than the sun; that the light of Sirius is four times as
great, and its parallax much less; so that by such a calculation Sirius
would have an intrinsic splendor sixty-three times that of the sun. But
Wallaston only calculates his light at one-fourth of this amount; and
Steinheil makes it only one t