Scientific American Supplement, No. 433, April 19, 1884

V >> Various >> Scientific American Supplement, No. 433, April 19, 1884

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THE PYRAMIDS OF MEROE.

About fifty miles from the mouth of the Atbara, and, of course, on the
eastern bank of the Nile, stand the pyramids of Meroe. They consist
of three groups, and there are, in all, about eighty pyramids. The
presumption is that they represent the old sepulchers of the kings of
Meroe. Candance, Queen of the Ethiopians, mentioned in Acts, chap.
viii., v. 27, is supposed to have belonged to Meroe, that being the name
also of the capital, which is understood to have been somewhere not far
distant from the sepulchers. These pyramids of Meroe possess one marked
feature, distinguishing them from the pyramids of Egypt proper--that is,
they have an external doorway or porch. As there is no entrance to the
pyramid at these porticoes, it is quite possible that they were temples
for worship or making offerings to the dead. By comparing them with
the pyramids of Ghizeh, it will be seen that they are also taller in
proportion to their base. Another important point in these porches
or temples is the existence of the arch; and that, too, an arch in
principle, with a keystone.--_Illustrated London News_.

[Illustration: THE PYRAMIDS OF MEROE, ON THE NILE.]

* * * * *

THE PROLIFICNESS OF THE OYSTER.

In an article by Prof. Karl Mobius on "The Oyster and Oyster Culture,"
reproduced in the recently issued report of the U. S. Commissioner of
Fish and Fisheries, the author says:

A mature egg-bearing oyster lays about one million of eggs, so that
during the breeding season there are upon our oyster beds at least
2,200,000,000,000 young oysters, which surely would suffice to transform
the entire extent of the sea-flats into an unbroken oyster bed; for if
such a number of young oysters should be distributed over a surface 74
kilometers long by 22 broad, 1,351 oysters would be allotted to every
square meter. But this sum of 2,200,000,000,000 young oysters is
undoubtedly less than that in reality hatched out, for not only do those
full-grown oysters which are over six years of age spawn, but they begin
to propagate during their second or third year, although it is true that
the young ones have fewer eggs than those which are fully developed. At
a very moderate estimation, the total number of three to six year old
oysters which lie upon our beds will produce three hundred billions of
eggs. This number added to that produced by the five millions of full
grown oysters would give for every square meter of surface not merely
1,351 young oysters, but at least 1,535. In order to determine how
many eggs oysters produce, they must be examined during their spawning
season. This begins upon the Schleswig-Holstein beds in the middle of
June, and lasts until the end of August or beginning of September. The
spawning oyster does not allow its ripe eggs to fall into the water, as
do many other mollusks, but retains them in the so-called beard, the
mantle, and gill-plates until they become little swimming animals. The
eggs are white, and cover the mantle and gill-plates as a semi-fluid,
cream-like mass. As soon as they leave the generative organs the
development of the germ begins. The entire yolk-mass of the egg divides
into cells, and these cells form a hollow, sphere-like body, in which an
intestinal canal arises by the invagination of one side. Very soon the
beginnings of the shell appear along the right and left sides of the
back of the embryo, and not long afterward a ciliated pad, the velum, is
formed along the under side. This velum can be thrust out from between
the valves of the shell at the will of the young animal, and used by the
motion of its cilia as an organ for driving food to the mouth, or
in swimming as a rudder. During these transformations the original
cream-white color of the germ changes into pale gray, and finally into a
deep bluish-gray color. At this time they have a long oval outline, and
are from 0.15 to 0.18 of a millimeter in breadth. Over 300,000 can find
room upon a square centimeter of surface. If an oyster in which the
embryos are in this condition is opened, there will be found upon its
beard a slimy coating thickly loaded with grayish-blue granules. These
granules are the embryo oysters, if a drop of the granular slime be
placed in a dish with pure sea water, the young animals will soon
separate from the mass, and spread swimming through the entire water.
When the embryos are at this stage their number may be estimated in the
following manner: The whole mass of embryos is carefully scraped from
the beard of the mother oyster by means of a small hair brush. The whole
mass is then weighed, and afterward a small portion of the mass. This
small portion is then diluted with water or spirits of wine, and the
embryos portioned out into a number of small glass dishes, so that they
can be placed under the microscope and counted. Thus, knowing the weight
of the small portion and the number of embryos in it by count, we can
estimate the total number of embryos from the weight of the entire mass,
which is also known. In this manner I estimated the number of embryos
in each of five full grown Schleswig-Holstein oysters caught in August,
1869, and found that the average number was 1,012,956.

Notwithstanding this great fecundity, but an extremely small proportion
of the young oysters produced during the course of the summer arrive
at maturity, 421 only out of 500,000,000 escaping destruction. The
immolation of a vast number of young germs is the means by which nature
secures to a few germs the certainty of arriving at maturity. In order
to render the ideas of germ-fecundity and productiveness more easily
understood, Prof. Mobius makes the following comparison between the
oyster and man:

According to Wappaus, for every 1,000 men there are 347 births.
According to Bockh, out of every 1,000 men born 554 arrive at maturity,
that is, live to be twenty years or more of age; thus, on an average,
347 children are produced from 554 mature men, or 626 children from
1,000 mature men. Since 1,000 full-grown oysters produce 440,000,000 of
germs, then the germ fecundity of the oyster is to the germ fecundity of
man as 440,000,000 to 6.26, or as 7,028,754 to 1. On the other hand, the
number which arrive at maturity is 579,002 times as great with mankind
as with the oyster; for of 1,000 human embryos brought into the world
554 arrive at maturity, or of 440,000,000 newly born 243,760,000 would
live to grow up, while of 440,000,000 young oysters only 421 ever become
capable of propagating their species. The proportion is then 421 to
243,760,000, or as 1 to 579,002. I am fully persuaded that these figures
represent the number of oysters which arrive at maturity more favorably
than is really the case, since from every thousand of full grown oysters
it is certain that, on an average, more than 440,000,000 young are
produced.

* * * * *

RED SKY.

The beautiful red sky which has been so frequent of late, morning as
well as evening, has excited much comment. The comment, however, has
consisted more of description, statement of fact, theory, and wonder as
to cause, rather than as to satisfactory explanation.

Facts in the case which would reveal the secret of this beautiful
display of nature are not complete and numerous enough at present to
establish the cause of this phenomenon on a sure basis; yet enough
facts, it would seem, have been obtained to satisfy the strong mind
capable of bridging over a wide expanse.

Facts in an argument are like piers to a bridge-the more we have of
them, c. p., the more substantial the structure. When the facts are
_legion_, the structure becomes a causeway, and there is no need of
argument.

Argument is a bridge--the fewer the facts, the more the necessity for
the bridge; the less the facts, the more argument necessary to connect
the few we have, and the more skill is required to make substantial
connecting links between the few solid piers (facts) that exist.

One of the queer things in connection with this is, the public have
looked chiefly, if not wholly, to the astronomers for an explanation
of this phenomenon, when it is not their special province to explain
matters in this department of nature.

The explanation belongs to the department of meteorology, and not to
astronomy. But the fact of having looked to the astronomers shows how
little the world knows of meteorology and how few meteorologists
there are able, ready, and willing to rise and explain in face of the
opposition of the public, who seem to think that the explanation must
necessarily belong to astronomy. Astronomy proper deals with the
position of the earth in space and its relation to the other heavenly
bodies, whether suns, fixed stars, planets, satellites, comets, or other
bodies in the vast space about us. Meteorology deals with the atmosphere
of the globe, in all its forms. Astronomy could be studied in the early
ages; its grand facts were not wholly dependent upon the advanced
condition of the mechanic arts; it could be studied even without the aid
of telescopes, though telescopes have added much to its advancement.
Meteorology, on the contrary, depended on the advancement of the arts
and sciences; they must first be perfected ere we could know much about
this branch of science. To one unfamiliar with the advancement and
perfection of meteorology within the past ten years, this statement
may seem strange, yet it is an undisputable fact that, prior to the
establishment of the daily weather reports, the knowledge on this
subject amounted to very little, and was not even worthy of being
designated a science. Prior to the advent of the weather map the world
was in absolute ignorance of the laws governing the atmosphere. Sure, we
had had large volumes on the laws of storms, but the later revelations
leave them shelved high and dry on the shores and as useless as a wreck
in a similar condition; with the daily weather map before us we have no
need to even open these huge volumes; they are completely circumvented,
and only negative in value--to show how little was known of the subject
without the full and complete facts daily collected and spread before us
on the map published by the Weather Bureau.

In order to understand the color of our sky, we must understand the
subject which is so immediately connected with it and its creation.

The earth is a sphere in space; generally speaking, it is composed of
land and water. These are two factors; the heat that it derives from
the sun forms a third factor; the three--land, water, and heat--are
essential to life, at least the higher conditions of life which
culminate in man. The old physical geography taught us this much, but
it was not able to go further and tell us why it was cold or warm
independent of the seasons; it could not explain why it was at times as
warm, and even warmer, half-way to the pole than at the equator; why it
was at times very warm in the extreme northeast while very cold in
the Southern States; cold in the northwest when it was warm in the
northeast, and warm in the northwest when cold all along the upper
Atlantic seaboard; it could not forewarn us of storms. These and a
host of other facts, which the weather map makes as plain as astronomy
demonstrates that Jupiter is a planet, the new revelation, through the
instrumentality of the perfected telegraph system, makes exceedingly
plain to us if we will but seek the easily obtained information.

The principal revelations of the weather map are the facts in regard to
the areas of high and low barometer, and the influence they exert upon
the climate of the globe.

These conditions--high and low barometer--move on general lines from the
west towards the east, or towards the rising sun, and around the world
in irregular belts. The centers of low barometer are various distances
apart, from a thousand to two thousand and even more miles apart--call
the average about two thousand miles.

The clouds are formed from the moisture present by the action of the
sun's heat. The direction of the wind is from the area of high barometer
to that of low. The nearer the winds approach the center of "low" (low
barometer), the more they partake of the lines of the volute curve, or
curve of the sea shell or water in a whirlpool. High barometer is the
atmospheric hill; low barometer is the atmospheric valley. But time at
present will not permit more than these general statements; a close
study of the weather map for a season will reveal the beautiful minor
details.

To the reader it may seem a long way round, yet in order to fully
understand the nature of the atmosphere which surrounds our globe we
must pay due attention to these newly discovered physical laws.

The red sky which was so noticeable, in the fall of 1883, the
astronomers have told us was due to "meteoric dust" which was produced
by the volcanic eruption on the island of Java, August 27, 1883.

This "meteoric dust" they say combined with the atmosphere, followed it
around the earth, and caused the beautiful redness of the sky at morning
and evening. For one, I do not believe dust of any description in the
atmosphere would produce such an effect.

There is nothing luminous, transparent, or delicate about dust. Dust
would not remain in the atmosphere for months, it would settle in a very
short time, and if thick enough in the atmosphere to obstruct the light
of the sun it would be visible, discernible, to the eye, and manifest
on the face of nature. Years ago, before the age of the weather map, we
might have thought that the atmosphere followed the surface of the earth
like the water on a grindstone, but it does not. As already seen, the
wind is from the area of high barometer to that of low, and there are
many of these "low centers."

From the best calculation we can make at present, there would be at
least some six centers on an average between the center of the United
States and the island of Java. In addition to this there would also be
a number of belts of "low" centers, which would complicate the thing
threefold at least. At all these different centers the winds would be
blowing from all points of the compass at the same time. Such winds
would not be apt to bring the "meteoric dust" from Java to the United
States, either in an easterly or westerly direction. But, it is said,
"dust" has been gathered.

How high from the surface of the ground has this _dust_ been
gathered--at what elevation?

There is undoubtedly a little dust in the air most of the time, but I do
not think that it extends very high. Where it would be the highest and
most perceptible would be on the arid plans of Africa and Asia, when
the _simoom_ is passing, or in the track of a tornado. But from the
multiplicity of these storm centers and the varied winds they would
produce even this dust could not travel from Java to America.

Again, all clouds, no matter how high or how low, are affected by the
low centers, as the movement of clouds prove, and travel from the "high"
to the "low," from and to all points of the compass. High authority
gives the heights of the clouds as follows: lower clouds, 16,000 feet;
upper clouds, 23,000 feet.

As all clouds, from the highest to the lowest, are affected by the
centers as above referred to, it follows that if this "meteoric dust"
follows the earth around, as it would have to do in order to make good
this theory, it would have to travel suspended in the atmosphere above
the upper clouds, or at a height of more than 23,000 feet, or at an
elevation of over four miles!

Now, is it reasonable to believe that dust, however fine, will remain in
the atmosphere at that elevation for over six months?

As a side argument it is suggested that the smoke of the burning woods,
or few years ago in Michigan, caused as peculiar condition of the
atmosphere. This extensive fire was on a day when the area of low
barometer was on a high line of latitude and passing to the eastward.
This naturally took the smoke, which is far lighter than dust, along
with it. It mingled with the muggy condition of an extensive "low," and
produced a yellowness of the atmosphere. This however was of only a few
hours' duration, and was only visible in favorable localities.

Here again we see the advantage of the weather maps; but for this map we
would never have been able to have satisfactorily explained the peculiar
phenomenon produced by the great Michigan fire.

If the delicate redness of the sky is not caused by dust, what is it
caused by?

But for the weather map, I think we should still be in the dark in
regard to it.

In the first place, this redness is nothing new, only the conditions
are more favorable sometimes than at others. It has always existed and
always will exist, independent of earthquakes, volcanoes, etc. Nature
is ever changing; the movements of the atmosphere more resemble the
kaleidoscope than any thing else.

The summer and fall of 1883, the movements of "high" (high barometer)
over the United States were quite central and extensive, causing this
peculiar phenomenon over a wide extent of territory.

We have no information of the condition of the barometer over the other
part of the world; we speak move particularly of the United States; yet
if certain conditions produce certain effects here, it is quite safe to
say that the same effects are produced by the same cause elsewhere.

As now well established by the map, the surface wind is from the area
of high barometer to that of low--from the atmospheric hill to the
atmospheric valley.

The tendency of this is to free "high" of all clouds and moisture; but
then it is impossible to free "high" entirely of moisture; a little
will remain, and it is just this little, which is highly rarefied, that
produces the result. We look around us and above, we see little or no
evidence of evaporation, yet it is the while going on. When the sun is
immediately below the horizon, where it will shine horizontally through
the mass of light, suspended moisture, the delicate presence of vapor
heretofore unnoticed is revealed. The action of the sun's rays is the
same as when illuminating a well formed cloud--it is an embodiment
of the same principle, but the material is much more expanded. The
particles of suspended moisture are very fine, few and far between,
therefore the effect of the light upon it is more diffused and
transparent. It is much like looking through a piece of window glass
flatwise and endwise; flatwise we do not perceive any color; endwise,
from seeing through a greater mass, the glass has a very perceptible
green color.

We see the same idea also in the rising and setting sun and moon. On
a clear, cloudless night, when nothing seems to interfere with the
brightness of the stars, we cannot, by looking upward, perceive any
moisture present in the atmosphere; but if we cast our eyes to the
horizon, whereby we see through the mass of atmosphere endwise, as it
were, and note the appearance of the stars there, or the rising or
setting moon, we will see that the atmosphere there gives a redness
to the rising body, which it does not have when it has ascended to
mid-heaven. On a clear night, which is caused by the presence of the
area of high barometer, the moon when in mid-heaven is of a clear,
silver-white, and it is the same moon that at the horizon was a deep
red. The color of the moon has not changed; it is simply the medium
through which it is seen that produces the difference in color.

Occasionally, on a clear, bright ("high") night, when the moon is full,
prior to rising, when just below the horizon, it will so illuminate this
lower strata of atmosphere as to appear like a great fire; the moon
rises red, but its deep color gradually fades as it rises, and when well
up in the heavens we perceive that this deep coloring was an illusion
and merely the influence of its surroundings. I never, though, knew of
any one to attempt to account for this by "meteoric dust;" and yet it is
an embodiment of the same principle. Place the sun where the moon is,
and from its far superior abundance of light we have a much grander
display.

Under no other conditions or relations of the sun and earth is it
possible to have this phenomenon of the delicate red sky but when a
positive area of high barometer is passing and extends over us. In
order to produce this effect we must have the clear atmosphere of high
barometer, when there is a minimum of moisture present. The action of
the sun's rays upon this extensive area of slightly moist rarefied
air is unconfined by clouds, and reaches far and wide, and produces
a delicacy of color which from no other source or condition can be
realized.

ISAAC P. NOYES.

Washington, D. C., 1884.

* * * * *

A THEORY OF COMETARY PHENOMENA.

_To the, Editor of the Scientific American_:

The following subject, substantially, was written more than a year ago
with a view to its publication. It was not, however, until January of
the present year that I sent a brief communication to the _Brooklyn
Eagle_, which was published Feb. 3, giving my views in relation to
cometary phenomena. With this I might remain satisfied, were it not
that the interesting paper by G. D. Hiscox, published in the SCIENTIFIC
AMERICAN SUPPLEMENT, Feb. 16, impressed me with the idea that the theory
I advanced might assist in explaining others, if brought to the notice
of those interested through the columns of your valuable journal.

The theory that I advance to account for the several phenomena relating
to comets' tails is, that comets are non-luminous, transparent bodies;
that they transmit the light of the sun; that the transmitted light
reflected by the particles of matter in space constitutes the tails of
comets. "Like causes produce like effects." By contraries, then, like
effects must be produced by similar causes; for, if an effect produced
by a cause which is known is similar to an effect produced by a cause
which is not known, the cause which is known must be similar to the
cause which is not known. This is true or not.

I submit the following experiments to substantiate the theory advanced.

Partially fill a vial or a tumbler with water, hold it by the rim,
and move it around a lighted candle placed upon a table. A shadow
surrounding the transmitted light will be cast upon the table. As the
tumbler approaches the light, the shadow follows the tumbler, and when
receding the tumbler follows the shadow; and as the tumbler is moved
around the light, the shadow will swing round from one side to the
other. If the tumbler be held so that a puff of smoke can be blown
into the transmitted rays, the particles of smoke will reflect the
transmitted light, and will illustrate my idea of what constitutes a
comet's tail. A dark band may be observed in this stream of light, as
also in the light cast upon the table.

In these experiments, we see the effects produced by a cause which is
known; the effects are similar to those observed in the tails of comets,
the cause of which we do not know; but is it not reasonable to assume
that the cause is similar?

Assuming now that comets are transparent, can any other phenomena
peculiar to comets be accounted for upon this hypothesis? Next to
the tail itself, the curve is the most noticeable feature, and if we
consider the extraordinary length of these appendages, the astounding
velocity at which comets move in their orbits, and the time that would
elapse before a ray of light, emitted from the nucleus, would reach the
end of the tail, perhaps the curve--which, if I am not deceived in my
observations, always dips toward its orbit--can be accounted for. If a
comet moved in a direct line toward the center of the sun, there would
be no curve to the tail. But taking Donati's comet of 1858 as an
example, the tail of which was said to be about 200,000,000 miles long,
a ray of light traveling at the rate of 192,000 miles per second would
be about twenty minutes in going from the nucleus to the end of the
tail.

But during that time the comet would move in its orbit, say, 50,000
miles, and as light moves in a straight line, and other rays are
constantly emerging from the nucleus as it moves along in its course,
the result is that the tail has a curved appearance.

I have no data at hand regarding this comet, but what I have said will
serve to illustrate my ideas. Again, referring to this comet, I remember
to have read the statement of an astronomer that, after passing round
the sun, a new tail was formed opposite the original one. Now, it seems
to me that that is just what would happen, for in moving round the sun
the comet would travel say 3,000,000 miles; the greater portion of the
tail then, would extend millions of miles upon one side of the sun,
while from the nucleus upon the opposite side of the sun a new tail
would appear to be formed.

Upon this hypothesis, the extraordinary length of their tails and the
fact that stars are visible through the densest portion of them is
explained; as also the fact that they so rapidly disappear from view
when moving from the sun, the light received by them from the sun
being in proportion to their distance from it, and but little of that
reflected.

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