ASTRONOMICAL FOUNDATION OF TIME
Astronomical motions on which our time is founded. -- Reasons
for selecting the sidereal day as a basis for our 24-hour
day. -- Year of the seasons shorter than the zodiacal year. --
Precession of the equinoxes. -- Earth's rotation most uniform
motion known to us. -- Time Stars and Transits. -- Local time.
-- The date line. -- Standard time. -- Beginning and ending of
a day. -- Proposed universal time. -- Clock dial for universal
time and its application to business. -- Next great improvement
in clocks and watches indicated. -- Automatic recording of
the earth's rotation. -- Year of the seasons as a unit for
astronomers. -- General conclusions.
The mystery of time encloses all things in its folds, and our grasp
of its infinite bearings is measured by our limitations. As there
are no isolated facts in the Universe, we can never get to the end
of our subject; so we know only what we have capacity to absorb.
In considering the foundation on which all our time measuring
is based, we are led into the fringe of that Elysian field of
science--astronomy. A science more poetical than poetry--more charming
than the optimistic phantasies of youth. That science which leaves
our imagination helpless; for its facts are more wonderful than our
extremest mental flights. The science of vastness and interminable
distances which our puny figures fail to express. "The stars sang
together for joy," might almost be placed in the category of facts;
while the music of the spheres may now be considered a mathematical
reality. Our time keeping is inevitably associated with these
motions, and we must select one which has periods not too long. That
is, no _continuous_ motion could be used, unless it passed some
species of milestones which we could observe. Consequently, our
clocks do not--in the strict sense--measure time; but are adjusted
to _divide_ periods which they do not determine. We are constantly
correcting their errors and never entirely succeed in getting them
to run accurately to _periods of time_ which exist entirely outside
of such little things as men and clocks. So a clock is better as it
approximates or bears a regular _relation_ to some motion in nature.
The sidereal clock of the astronomer _does_ run to a regular motion;
but our 24-hour clocks _do not_, as we shall see later. Now consider
the year, or the sun's apparent motion in the Zodiac, from any given
star around to the same one again. This is altogether too long to be
divided by clocks, as we cannot make a clock which could be depended
on for anywhere near a year. The next shorter period is that of a
"moon." This is also a little too long, is not easily observed, and
requires all sorts of corrections. Observations of the moon at sea
are so difficult and subject to error that mariners use them only
as a last resort. If a little freedom of language is permissible, I
would say that the moon has a bad character all around, largely on
account of her long association with superstition, false theology
and heathen feasts. She has not purged herself even to this day!
The ancients were probably right when they called erratic and
ill-balanced persons "luny." Now we come to the day and find that it
is about the right practical length--but what kind of a day? As there
are five kinds we ought to be able to select one good enough. They
are:--
1st. The solar day, or noon to noon by the sun.
2nd. An imaginary sun moving uniformly in the ecliptic.
3rd. A second imaginary sun moving uniformly parallel to the
equator at all seasons of the year.
4th. One absolute rotation of the earth.
5th. One rotation of the earth measured from the node, or
point, of the spring equinox.
The difference between 1st and 2nd is that part of the sun's error
due to the elliptical orbit of the earth.
The other part of the sun's error--and the larger--between 2nd and 3rd
is that due to the obliquity of the ecliptic to the equator.
The whole error between 1st and 3rd is the "equation of time" as
shown for even minutes in the first chapter under the heading, "Sun
on Noon Mark 1909."
Stated simply, for our present purpose, 1st is sundial time, and 3rd
our 24-hour clock time.
This 2nd day is therefore a refinement of the astronomers to
separate the two principal causes of the sun's error, and I think we
ought to handle it cautiously, or my friend, Professor Todd, might
rap us over the knuckles for being presumptuous.
This 5th day is the sidereal day of the astronomers and is the basis
of our time, so it is entitled to a little attention. I shall confine
"sidereal day" to this 5th to avoid confusion with 4th. If you will
extend the plane of the equator into the star sphere, you have the
celestial equator. When the center of the sun passes through this
plane on his journey north, in the Spring, we say, "the sun has
crossed the line." This is a distant point in the Zodiac which can
be determined for any given year by reference to the fixed stars. To
avoid technicalities as much as possible we will call it the point
of the Spring equinox. This is really the point which determines
the common year, or year of the seasons. Using popular language,
the seasons are marked by four points,--Spring equinox--longest day--;
Autumnal equinox--shortest day. This would be very simple if the
equinoctial points would stay in the same places in the star sphere;
but we find that they creep westward each year to the extent of 50
seconds of arc in the great celestial circle of the Zodiac. This is
called the precession of the equinoxes. The year is measured from
Spring equinox to Spring equinox again; but each year it comes 50
seconds of arc less than a full revolution of the earth around the
sun. Therefore _if we measured our year by a full revolution_ we
would displace the months with reference to the seasons till the
hot weather would come in January and the cold weather in July in
about 13,000 years; or a complete revolution of the seasons back to
where we are, in 26,000 years. Leaving out fractions to make the
illustration plain, we have:--
(1) 360 degrees of Zodiac }
--------------------- = 26,000 years }
50 seconds of arc }
}
(2) 1 day of time }
------------- = 26,000 years }
3-1/3 seconds } All
} Approximate
(3) 1 year of time }
-------------- = 26,000 years }
20-1/3 minutes }
}
(4) 3-1/3 seconds }
------------- = 1/110 of a second}
days in a year }
In (1) we see that a "precession" of 50 seconds of arc will bring the
Spring equinox around in 26,000 years.
In (2) we see, as 50 seconds of arc represents the distance the earth
will rotate in 3-1/3 seconds, a difference of one day will result
in 26,000 years. That is since the clock regulated by the stars, or
absolute rotations of the earth, would get behind 3-1/3 seconds per
year, it would be behind a day in 26,000 years, as compared with a
sidereal clock regulated by the Spring equinoctial point.
In (3) we see that as 50 seconds of arc is traversed by the earth, in
its annual revolution, in 20-1/3 minutes, a complete circle of the
Zodiac will be made in 26,000 years.
In (4) we see that as the difference between the year of the seasons
and the Zodiacal year is 3-1/3 seconds of the earth's rotation, it
follows that if this is divided by the number of days in a year
we have the amount which a sidereal day is less than 4th, or an
absolute rotation of the earth. That is, any meridian passes the
Spring equinoctial point 1/110 of a second sooner than the time of
one absolute rotation. These four equations are all founded on the
precession of the equinoxes, and are simply different methods of
stating it. Absolutely and finally, our time is regulated by the
earth's rotation; but strange as it may appear, we do not take one
rotation as a unit. As shown above, we take a rotation to a _movable
point_ which creeps the 1/110 of a second daily. But after all, it is
the _uniform_ rotation which governs. This is the one "dependable"
motion which has not been found variable, and is the most easily
observed. When we remember that the earth is not far from being as
heavy as a ball of iron, and that its surface velocity at the equator
is about 17 miles per minute, it is easy to form a conception of its
uniform motion. Against this, however, we may place the friction
of the tides, forcing up of mountain ranges, as well as mining and
building skyscrapers--all tending to slow it. Mathematicians moving in
the ethereal regions of astronomy lead us to conclude that it _must_
become gradually slower, and that _it is_ slowing; but the amount may
be considered a vanishing quantity even compared with the smallest
errors of our finest clocks; so for uncounted generations past--and to
come--we may consider the earth's rotation uniform. Having now found
a uniform motion easily observed and of convenient period, why not
adopt it as our time unit? The answer has been partially given above
in the fact that we are compelled to use a year, measured from the
Spring equinoctial point, so as to keep our seasons in order; and
therefore as we must have some point where the sidereal clocks and
the meantime clocks coincide, we take the same point, and that point
is the Spring equinox. Now we have three days:--
1st. A sidereal day 1/110 of a second less than one rotation of
the earth.
2nd. One rotation of the earth in 23 hours, 56 minutes and 4
seconds, nearly, of clock time.
3rd. One mean time clock day of 24 hours, which has been explained
previously.
Now, isn't it remarkable that our 24-hour day is purely artificial,
and that nothing in nature corresponds to it? Our real day of 24
hours is a _theoretical_ day. Still more remarkable, this theoretical
day is the unit by which we express motions in the solar system. A
lunar month is days--hours--minutes--and seconds of this theoretical
day, and so for planetary motions. And still more remarkable, the
earth's rotation which is _itself_ the foundation is expressed in
this imaginary time! This looks like involution involved, yet our
24-hour day is as real as reality; and the man has not yet spoken who
can tell whether a mathematical conception, sustained in practical
life, is less real than a physical fact. Our legal day of practical
life is therefore deduced from the day of a fraction _less_ than one
earth rotation. In practice, however, the small difference between
this and a rotation is often ignored, because as the tenth of a
second is about as near as observations can be made it is evident
that for single observations 1/110 of a second does not count, but
for a whole year it does, and amounts to 3-1/3 seconds. Now as to
the setting of our clocks. While the time measured by the point of
the Spring equinox is what we must find it is found by noting the
transits of fixed stars, because _the relation_ of star time to
equinoctial time is known and tabulated. Remember we cannot take
a transit of the equinoctial point, because there is nothing to
see, and that _nothing_ is moving! But it can be observed yearly
and astronomers can tell where it is, at any time of the year, by
calculation. The stars which are preferred for observation are
called "time stars" and are selected as near the celestial equator
as possible. The earth's axis has a little wabbling motion called
"nutation" which influences the _apparent_ motion of the stars near
the pole; but this motion almost disappears as they come near the
equator, because nutation gives the plane of the equator only a
little "swashplate" motion. The positions of a number of "time stars"
with reference to the equinoctial point, are known, and these are
observed and the observations averaged. The distance of any time
star from the equinoctial point, _in time_, is called its "right
ascension." Astronomers claim an accuracy to the twentieth part of
a second when such transits are carefully taken, but over a long
period, greater exactness is obtained. Really, the time at which any
given star passes the meridian is taken, _in practical life_, from
astronomical tables in the Nautical Almanacs. Those tables are the
result of the labors of generations of mathematicians, are constantly
subject to correction, and cannot be made simple. Remember, the
Earth's rotation is the only uniform motion, all the others being
subject to variations and even compound variations. This very subject
is the best example of the broad fact that science is a constant
series of approximations; therefore, nothing is exact, and nothing
is permanent but change. But you say that mathematics is an exact
science. Yes, but it is a _logical abstraction_, and is therefore
only the universal solvent in physical science.
With our imaginary--but real--time unit of 24 hours we are now ready
to consider "local time." Keeping the above explanation in mind, we
may use the usual language and speak of the earth rotating in 24
hours clock time; and since motion is relative, it is permissible to
speak of the motion of the sun. In the matter of the sun's apparent
motion we are compelled to speak of his "rising," "setting," etc.,
because language to express the motion in terms of the earth's
rotation has not been invented yet. For these reasons we will assume
that in Fig. 47 the sun is moving as per large arrow and also that
the annulus, half black and half white, giving the 24 hours, is
fastened to the sun by a rigid bar, as shown, and moves around the
earth along with him. In such illustrations the sun must always be
made small in proportion, but this rather tends to plainness. For
simplicity, we assume that the illustration represents an equinox
when the sun is on the celestial equator. Imagine your eye in the
center of the sun's face at A, and you would be looking on the
meridian of Greenwich at 12 noon; then in one hour you would be
looking on 15° west at 12 noon; but this would bring 13 o'clock to
Greenwich. Continue till you look down on New York at 12 noon, then
it is 17 o'clock at Greenwich (leaving out fractions for simplicity)
etc. If you will make a simple drawing like Fig. 47 and cut the
earth separate, just around the inside of the annulus, and stick a
pin at the North Pole for a center, you may rotate the earth as per
small arrow and get the actual motion, but the result will be just
the same as if you went by the big arrow. We thus see that every
instant of the 24 hours is represented, at some point, on the earth.
That is, the earth has an infinity of local times; so it has every
conceivable instant of the 24 hours at some place on the circle.
Suppose we set up 1,410 clocks at uniform distances on the equator,
then they would be about 17 miles apart and differ by minutes. Now
make it 86,400 clocks, they would be 1,500 feet apart and differ by
seconds. With 864,000 clocks they would be 150 feet apart and vary
by tenths of seconds. It is useless to extend this, since you could
always imagine more clocks in the circle; thus establishing the
fact that there are an infinity of times at an infinity of places
always on the earth. It is necessary to ask a little patience here
as I shall use this local time and its failure later in our talk.
Strictly, local time has never been used, because it has been found
impracticable in the affairs of life. This will be plain when we draw
attention to the uniform time of London, which is Greenwich time; yet
the British Museum is 30 seconds slow of Greenwich, and other places
in London even more. This is railroad time for Great Britain; but
it is 20 minutes too fast for the west of England. This led to no
end of confusion and clocks were often seen with two minute hands,
one to local and the other to railroad time. This mixed up method
was followed by "standard time," with which we are all pretty well
acquainted. Simply, standard time consists in a uniform time for each
15° of longitude, but this is theoretical to the extreme, and is not
even approached in practice. The first zone commences at Greenwich
and as that is near the eastern edge of the British Islands, their
single zone time is fast at nearly all places, especially the west
coast of Ireland. When we follow these zones over to the United
States we find an attempt to make the middle of each zone correct to
local time, so at the hour jumping points, we pass from half an hour
slow to half an hour fast, or the reverse. We thus see that towns
about the middle of these four United States zones have sunrise and
sunset and their local day correct, but those at the eastern and
western edges average half an hour wrong. As a consequence of this
disturbance of the working hours depending on the light of the day,
many places keep two sets of clocks and great confusion results. Even
this is comprehensible; but it is a mere fraction of the trouble
and complication, because the hour zones are not separated by
meridians in practice, but by zig-zag lines of great irregularity.
Look at a time map of the United States and you will see the zones
divided by lines of the wildest irregularity. Now question one of
the brightest "scientific chaps" you can find in one of the great
railroad offices whose lines touch, or enter, Canada and Mexico.
Please do not tell me what he said to you! So great is the confusion
that no man understands it all. The amount of wealth destroyed in
printing time tables, _and failing to explain them_, is immense. The
amount of human life destroyed by premature death, as a result of
wear and tear of brain cells is too sad to contemplate. And all by
attempting the impossible; for local time, _even if it was reduced to
hourly periods_ is not compatible with any continental system of time
and matters can only get worse while the attempt continues. For the
present, banish this zone system from your mind and let us consider
the beginning and ending of a day, using strictly local time.
[Illustration: Fig. 47--Local Time--Standard Time--Beginning and
Ending of the Day]
A civil, or legal, day ends at the instant of 24 o'clock, midnight,
and the next day commences. The time is continuous, the last instant
of a day touching the first instant of the next. This is true for
all parts of the earth; but something _in addition_ to this happens
at a certain meridian called the "date line." Refer again to Fig. 47
which is drawn with 24 meridians representing hours. As we are taking
Greenwich for our time, the meridians are numbered from 0°, on which
the observatory of Greenwich stands. When you visit Greenwich you
can have the pleasure of putting your foot on "the first meridian,"
as it is cut plainly across the pavement. Degrees of longitude are
numbered east and west, meeting just opposite at 180°, which is
the "date line." Our day begins at this line, so far as _dates_ are
concerned; but the _local day_ begins everywhere at midnight. Let
us start to go around the world from the date line, westward. When
we arrive at 90° we are one quarter around and it takes the sun 6
hours longer to reach us. At 0° (Greenwich) we are half around and
12 hours ahead of the sun motion. At 90° west, three quarters, or 18
hours, and when back to 180° we have _added_ to the length of all
days of our journey enough to make one day; therefore our date must
be one day behind. Try this example to change the wording:--Let us
start from an island B, just west of the date line. These islanders
have their 24-hour days, commencing at midnight, like all other
places. As we move westward our day commences later and later than
theirs, as shown above. Suppose we arrive at the eastern edge of
the 180° line on Saturday at 12 o'clock, but before we cross it we
call over to the islanders,--what day is it? We would get answer,
"Sunday;" because all our days have been longer, totalling one day in
the circuit of the globe. So if we step over the line at 12 o clock
Saturday, presto, it is 12 o'clock Sunday. It looks like throwing out
24 hours, but this is not so, since we have lived exactly the same
number of hours and seconds as the islanders. In this supposition
we have all the _dates_, however, but have jumped half of Saturday
and half of Sunday, which equals one day. In practice this would not
have been the method, for if the ship was to call at the island, the
captain would have changed date on Friday night and thrown Saturday
out, all in one piece, and would have arrived on their Sunday; so
his log for that week would have contained only 6 days. It is not
necessary to go over the same ground for a circuit of the globe
eastward, but if you do so you will find that you _shorten_ your days
and on arriving at the date line would have a day too much; so in
this case you would _double_ a date and have 8 days in that week. In
both cases this is caused by compounding your motion with that of the
sun; going with him westward and lengthening your days, or eastward
meeting him and shortening them. Figure 47 shows Greenwich noon, we
will say on Monday, and at that instant, Monday only, exists from 0
to 24 o'clock on the earth; but the next instant, Tuesday begins at
180° B. In one hour it is noon of Monday at 15° West, and midnight
at 165° East; so Tuesday is one hour old and there is left 23 hours
of Monday. Monday steadily declines to 0 as Tuesday steadily grows
to 24 hours; so that, except at the instant of Greenwich noon, there
are always two days on the world at once. If we said that there are
_always_ two days on the world at once, we could not be contradicted;
since there is no conceivable time between Monday and Tuesday; it
is an instantaneous change. As we cannot conceive of _no time_,
the statement that there is only one day on the earth at Greenwich
noon is not strictly permissible. Since there are always two days
on the world at once let us suppose that these two are December
31st and January 1st; then we have _two years_ on the world at once
for a period of 24 hours. Nine years ago we had the 19th and 20th
centuries on the world at once, etc. As a mental exercise, you may
carry this as far as you please. Suppose there was an impassable sea
wall built on the 180° meridian, then there would be two days on the
world, just as explained above; but, _practically_, there would be
no date line, since in sailing west to this wall we would "lengthen
our days," and then shorten them the same amount coming around east
to the other side of the wall, but would never jump or double a date.
This explanation is founded, as it ought to be, on uniform local
time, and is the simplest I can give. The date line is fundamentally
simple, but is difficult to explain. When it is complicated by the
standard time--or jumping hour system--and also with the fact that
some islands count their dates from the wrong side of the line for
their longitudes, scientific paradoxes arise, such as having three
dates on the world at once, etc.; but as these things are of no more
value than wasting time solving Chinese puzzles, they are left out.
Ships change date on the nearest night to the date line; but if they
are to call at some island port in the Pacific, they may change
either sooner or later to correspond with its date. Here is a little
Irish date line wit printed for the first time,--I was telling my
bright friend about turning in on Saturday night and getting up for
breakfast on Monday morning. "Oh," said he, "I have known gentlemen
to do as good as that without leaving New York City!"
As what is to follow relates to the growing difficulties of local
time and a proposed method of overcoming them, let us recapitulate:--
1st. Local time has never been kept, and the difficulties of
using it have increased as man advanced, reaching a climax of
absurdity on the advent of the railroad; so it broke down and
became impractical.
2nd. To make the irregular disorder of local time an orderly
confusion, the "standard time"--jumping by hours--has helped a
little, but only because we can tell how much it is wrong at
any given place. This is its only advantage over the first
method, where we had no means of knowing what to expect on
entering any new territory. That is, we have improved things by
throwing out local time to the extent of an hour.
My proposal is to throw local time out _totally_ and establish one,
invariable, _universal time_. Greenwich time being most in use now,
and meridians numbered from it, may be taken in preference to any
other. Still another reason is that the most important timekeepers in
modern life--ship's chronometers--are set to Greenwich time. Universal
time--no local time--only local day and night. Our 24-hour system is
all right, so do not disturb it, as it gets rid of A.M. and P.M. and
makes the day our unit of time. Our railroad time now throws out
local time to the extent of one hour; but I propose to throw it out
entirely and never change the clock hands from Greenwich time. The
chronometers do that now, so let us conduct all business to that time.
Now refer to Fig. 46, in which Greenwich is taken as universal time.
The annulus, half white and half black, indicates the average day and
night, and is a separate ring in the dial which can be set so that
"noon" is on the meridian of the place, as shown for four places in
the illustration. It is the same dial in all four cases set to local
day and night. Strictly, the local time conception is dropped and the
local day left for regulating working and sleeping time. All business
would have the same time. In traveling east we would not have the
short hours; or west, the long hours. All clocks and watches would
show the same time as ship's chronometers do now. The only change
would be the names of the hours for the parts of the local day.
This is just the difficulty, for we are so accustomed to _associate_
a certain number, as seven, with the morning and breakfast time.
Suppose breakfast time in London is 7 o'clock, then according to the
local day it would be 12 o'clock breakfast time in New York; but in
both cases it would be the same time with reference to the _local
daylight_. Let it be distinctly understood that our association of
_12 o'clock_ with _noon_ is not necessary. The Japanese called it
"horse" and "nine"--the ancient Romans, the New Testament writers,
and the Turks called it the "sixth hour"--the astronomers now call it
24 o'clock, and the Chinese represent it by several characters; but,
in all cases, it is simply the middle of the day at any place. By
the proposed universal time, morning, noon, and evening would be--_at
any given place_--the same hours. There would be no necessity of
establishing legal noon with exactness to the meridian, because that
would only regulate labor, meals, etc., and would not touch universal
time. This is an important part of the proposal and is worth
elaborating a little. Sections in manufacturing districts could make
their working hours correspond at pleasure and no confusion would
result. That is, local working hours to convenience but by the same
universal time. Note how perfectly this would work in traveling,--you
arrive in Chicago from the effete east and your watch corresponds
all along with the railroad clocks. As you leave the station you
glance up at the clock and see that Chicago noon is 17.30, so you
set the day and night ring of your watch to match the same ring on
the clock, but no disturbance of the hands. As you register at the
hotel you ask,--dinner? and get answer, 24.30--then breakfast, 12.30.
These questions are necessary now, so I do not add complication
here. When you arrive in a strange city you must ask about meals,
business hours, theater hours, "doors open" hours, etc., etc.; so
all this remains the same. Let us put the matter forcibly,--while we
count days, or _dates_, _something_ must vary with east and west;
I propose the fixing of hours for business and sleep to suit each
locality, but an invariable time. Get rid of the idea that a certain
number, as 7 o'clock, represents the age of the day _at all places_.
See how this would wipe out the silly proposal to "save daylight"
by setting the clock back and forward. Suppose workmen commenced at
12.30 in New York; for the long summer days make it 11.30, but no
change in universal time. As this is the only difference from our
present time system, keep the central conception, firmly,--universal
time--local day and night.
[Illustration: Fig. 46--Universal Time Dial Set for Four Places]
Suppose Chicago decided that "early to bed and early to rise" was
desirable; then it could establish its legal noon as 17.30, which
would be about 20 minutes early for its meridian. You could do
business with Chicago for a lifetime and not find this out, unless
you looked up the meridian of Chicago and found that it was 17.50
o'clock. None of the railroads or steamship lines of the city would
need to know this, except as a matter of scientific curiosity,
for the time tables would all be printed in universal time. For
hiring labor, receiving and delivering goods, etc., they would
only need to know Chicago _business hours_. To state the matter in
different words,--Chicago would only need to decide what portion of
the universal 24 hours would suit it best for its day and which
for its night, and if it decided, as supposed above, to place its
working day forward a little to give some daylight after labor,
nothing would be disturbed and only the scientific would ever
know. Certainly, "save daylight," but do not make a fool of the
clock! Having shown the great liberty which localities could take
without touching the working of the system, the same remarks apply
to ultra-scientific localities. A city might establish its noon to
the instant; so it is possible--even if a little improbable--that
the brilliant and scientific aldermen of New York might appoint
a commission with proper campfollowers and instrument bearers to
determine the longitude of the city to the Nth of a second and tell
us where we "are at." The glory of this achievement--and especially
its total cost--would be all our own and incorruptible time would be
untouched! We thus see that great local freedom and great accuracy
are alike possible. With our present system, accuracy in local time
is impracticable and has never even been attempted, and is confusion
confused since we added the railroad hour jumps. Why did we nurse
this confusion till it has become almost intolerable? Because man
has always been a slave to _mental associations, and habits_.
Primitive man divided the local day into parts and gave them names
and this mental attitude sticks to us after it has served its day.
The advantages of universal time could hardly be enumerated, yet we
can have them all by dropping our childish association of 7 o'clock
with breakfast time! Another example,--you visit a friend for a few
days and on retiring the first night you ask "what is your breakfast
hour"--"8 o'clock." You have to ask this question and recollect the
answer. Now tell me what difference it would make if the answer had
been 13 o'clock? None whatever, unless, perhaps, that is, you do not
like thirteen! You ask, how about ships? Ships now carry universal
time and only change the clock on deck to please the simple minded
passengers. How about the date line? No change whatever, so long
as we use _dates_ which means numbering local days. It is useless
multiplying examples; all difficulties disappear, as if by magic, the
moment we can free our minds of local time and the association of
the _same hour_ with the _same portion_ of the day at _all places_.
The great interest at present manifested in the attempts to reach
the North Pole calls for some consideration of universal time in
the extreme north. Commencing at the equator, it is easy to see
that the day and night ring, Fig. 46, would represent the days and
nights of 12 hours at all seasons. As we go north, however, this
ring represents the _average_ day and night. When we reach the Polar
Circle, still going north, the _daily_ rising and setting of the sun
gradually ceases till we reach the great one-year day at the Pole,
consisting of six months darkness and six months light. Let us now
assume that an astronomical observatory is established here and the
great equatorial placed precisely on the pole. At this point, _local
time_, _day and night_, and _the date line_, almost cease to have
a meaning. For this very reason universal time would be the only
practical method; therefore, it _more_ than stands the test of being
carried to the extreme. Universal time would regulate working and
sleeping here the same as at all other places. Strictly local time in
this observatory would be an absurdity, because in walking around the
telescope (pole) you would be in all instants of the 24 hours within
five seconds! At the pole the day would commence at the same instant
as at some assumed place, and the day and night ring would represent
working and sleeping as at that place. Suppose this observatory to
be in telegraphic communication with New York, then it would be
best for the attendants to set their day and night to New York, so
as to correspond with its business hours. Many curious suppositions
might be made about this polar observatory with its "great night"
and equally "great day." It is evident that to keep count of itself
it would be compelled to note _dates_ and 24-hour _days_ to keep in
touch with us; so it would be forced to adopt the local day of some
place like New York. This choice would be free, because a polar
observatory would stand on all the meridians of the earth at once.
We are now in a position to consider the next possible--and even
probable--improvement in our clocks and watches. To minimize the
next step it might be well to see what we can do now. Clocks are
often regulated by electric impulses over wires. Electricians inform
me that they can do this by wireless; but that owing to the rapid
attenuation of the impulses it cannot be done commercially, over
great distances. In the history of invention the first step was _to
do something_ and then find a way of doing it cheaply enough for
general use. So far as I know, the watch in the wearer's pocket has
not yet been regulated by wireless; but I am willing to risk the
statement that the editor of Popular Mechanics can name more than one
electrician who can do this. A watch to take these impulses might be
larger than our present watches, but it would not stay larger and
would ultimately become much smaller. You know what has happened
since the days of the big "onions" described in the third chapter.
Fig. 34; so get your electric watch and make it smaller at your
leisure. We have made many things commercially practicable, which
looked more revolutionary than this. Now throw out the mainspring,
wheels, pinions, etc., of our watches and reduce the machinery part
to little more than dial and hands and do the driving by wireless,
say, once every minute. I feel certain that I am restraining the
scientific imagination in saying that the man lives among us who can
do this. I repeat, that we now possess the elementary knowledge--which
if collated and applied--would produce such a watch.
Now I have a big question to ask--the central note of interrogation
in this little scientific conversation with you,--does the man
live who can make the earth automatically record its rotation?
Do not be alarmed, for I am prepared to make a guess as to this
possibility. A _direct_ mechanical record of the earth's rotation
seems hopeless, but let us see what can be done. You are aware
that some of the fixed stars have a distinct spectrum. It is not
unreasonable to suppose that an instrument could be made to record
the passage of such a star over the meridian. Ah, but you say, there
is no mechanical force in this. Do not hurry, for we have long been
acquainted with the fact that things which, apparently, have no
force can be made to liberate something which manifests mechanical
force. We could now start or stop the greatest steam engine by a
gleam of sunlight, and some day we might be able to do as much by the
lately discovered pressure of light. That is, we can now liberate
the greatest forces by the most infinitesimal, by steps; the little
force liberating one greater than itself, and that one another still
greater. A good example is the stopping of an electric train, from a
distance, by wireless. The standard clock in Philadelphia, previously
referred to, is a delicate instrument and its most delicate part,
having the least force, moves a little valve every minute, and by
several steps liberates the air pressure, 200 feet higher in the
tower, to move the four sets of great hands. I am not traveling
beyond the record when I say that the invisible actinic rays could be
used to liberate a great force; therefore what is there unreasonable
in the supposition that the displacement of the sodium line in the
spectrum of a star might be made to record the earth's rotation? So
I say to the electrician--the optician--the photographer--the chemist
and the mechanic.--get together and produce this watch. Permit me,
with conventional and intentional modesty, to name the new timepiece
_Chroncosmic_. For pocket use, it would be _Cosmic watch_. In the
first chapter I allowed to the year 2,000 for the production of this
watch, but it is likely we will not need to wait so long.
Having stated my proposal for universal time as fully as space will
permit and given my guess as to the coming cosmic watch, let us in
this closing paragraph indulge in a little mental exercise. Suppose
we copy the old time lecturer on astronomy and "allow our minds to
penetrate into space." Blessed be his memory, he was a doer of good.
How impressive as he repeatedly dropped his wooden pointer, and lo!
It always moved straight to the floor; thus triumphantly vindicating
universal gravitation!!!
We can think of a time system which would discard months, weeks and
days. What is the meaning of the financial almanac in which the
days are numbered from 1 to 365 or 366? Simply a step in the right
direction, _away from the months and weeks_, so that the distance
between any two dates may be seen at a glance. We would really be
better without months and weeks. Now let us consider the year of
the seasons as a unit--long since proposed by the astronomers--and
divide it into 3,000 chrons. Clocks regulated by star transits, as
at present, would divide this decimally, the fourth place being near
enough to make the new pendulums of convenient length. This would
throw out months, weeks and days, local time and the date line.
Each of these chrons would represent the same time in the year,
permanently. For example, 464.6731 would mark to a _dixmilliemechron_
(a little more than one second) the point reached in the year; while
the date does not, as I have shown in the first chapter. But you
still object that this is a great number of figures to use in fixing
a point in the year. Let us see what it takes to fix a point in the
year now, _August 24th, 11-16-32 P. M., New York standard time_. A
pretty long story, but it does not fix the point of the year even
then; for it would require the assistance of an astronomer to fix
such a point in _any given_ year, say 1909. But 464.6731 would be
eternally right in _absolute time_ of the seasons, and has only one
meaning, with no qualifications for any year whatever. I believe
the astronomers should use a method something like this. Ah, but
there is a difficulty in applying this to the affairs of daily life
which looks insurmountable. This is caused by the fact that the
_day_ and _year_ are incommeasurable. One of them cannot be exactly
expressed in terms of the other. They are like the diagonal and side
of a square. The day is now the unit and therefore the year has an
interminable fraction; conversely, if we make the year the unit, then
the day becomes an endless fraction. This brings us face to face with
the local day which we ignored in our scientific year unit. We _must_
regulate our labors, in this world, to day and night and, with the
year unit, the chrons would bear no fixed relation to day and night,
even for two days in succession. So the year unit and absolute time
must be left to the astronomers; but the _day unit_ and the uniform
world day of _universal time_ as explained in connection with Fig. 46
I offer as a practical system.
I am satisfied that all attempts to measure the year and the day
by the same _time yard stick_ must fail and keep us in our present
confusion. Therefore separate them once for all time. Brought down to
its lowest terms my final proposal is:--
1st. An equinoctial year unit for the astronomers, divided
somewhat as suggested, but no attempt to make the divisions
even approximate to days and hours. This would fix all
astronomical events, absolutely. A variation in the length of
the year would not disturb this system, since the year _itself_
would be the unit. In translating this astronomical, or year
unit time, into clock time, no difficulties would be added, as
compared with our present translation of sidereal time into
clock time. Deal with the _year unit_ and _day unit_ separately
and convert them mutually when necessary.
2nd. A universal mean time day of 24 hours, as now kept at
Greenwich, all human business being regulated by this time.
Dates and the date line as well as leap years all being
retained as at present.
3rd. Weight and spring clocks and watches to be superseded by
the cosmic clocks and watches regulated by wireless impulses
from central time stations, all impulses giving the same
invariable time for all places.
4th. Automatic recording of the earth's rotations to determine
this time.
To avoid any possibility of misunderstanding, I would advise never
counting a unit till it is completed. We do this correctly with our
hours, as we understand 24 o'clock to be the same as 0 o'clock. But
we do not carry this out logically, for we say 24.30. How can this
be so, since there is nothing more than 24 o'clock? It ought to be
simply 30 minutes, or 0 hour 30 minutes. How can there be any _hour_
when a new day is only 30 minutes old? This brings up the acrimonious
controversy, of some years ago, as to whether there was any "year
one." One side insisted that till one year was completed there could
only be months and days. The other side argued that the "year one"
commenced at 0 and that the month and date showed how much of it had
passed. Test yourself,--is this the year 1909, of which only 8 months
have passed; or is it 1909 and 8 months more? Regarding the centuries
there appears to be no difference of opinion that 1900 is completed,
and that we are in the 20th century. But can you tell whether we are
8 years and 8 months into the 20th century or 9 years and 8 months?
It ought to be, logically 1909 years _complete_ and 8 months of the
next year, which we must not count till it is completed. Take a
carpenter's rule, we say 1/4 in.--1/2 in.--3/4 in., but do not count
an inch till we complete it. When the ancients are quoted,--"about
the middle of the third hour" there is no mistake, because that means
2-1/2 hours since sunrise. If we said the 1909th year that would be
definite too, and mean some distance into that year. Popular language
states that Greenwich is on the "first meridian"; strictly, it is on
the zero meridian, or 0°. These matters are largely academic and I do
not look on them as serious subjects of discussion; but they are good
thought producers. Bidding you good-bye, for the present, it might
be permissible to state that this conversational article on Time was
intended to be readable and somewhat instructive; but especially to
indicate the infinity of the subject, that thought and investigation
might be encouraged.
* * * * * *
Transcriber's note:
Original spelling and grammar have mostly been retained. However, on
page 31, "clepsydral" was changed to "clepsydra".
Figures were moved from within paragraphs to between paragraphs. In
addition, some figures were originally out of numerical sequence;
they are now in sequence.