"Twentyfour hours" is a clumsy mode of expression

The change from night to day and day to night is so obvious that names to distinguish one from the other must have been among the earliest words in the vocabulary. Yet there is no term, even in English (which we like to think fairly well advanced) that will designate the whole period of twenty-four hours, except as we speak loosely of a "calendar day" for convenience' sake. "Twentyfour hours" is a clumsy mode of expression, and the compound words which astronomers have developed to suit their scientific needs are (as usual) still worse. This anomaly is far from proving that the men who invented our language were uninterested in time; rather the reverse.

We know from existing primitive societies, that men give explicit names to the things which interest them most; and as their interest becomes more acute they develop a terminology to suit the complications of their knowledge. General and abstract words are left to the realm of uninteresting subjects. The Eskimos today have only one word for "trees" because verdure lies outside their immediate province; but they have a dozen names to differentiate the varieties of snow all about them, and not one of these terms means just plain snow as more southerly peoples speak of it. In the same way a dog-fancier divides his favorite animals into collies, chows, Pekinese or Samoyedes, but never under any circumstances will he call a dog, a dog. If the animal passes his understanding, he can only refer to it as a cur.

So English, in common with a great many other languages, has developed words for day and night, morning, afternoon and evening, noon and midnight. As might be expected, Scotland, where the twilights are long, has its own colloquialisms for the "gloaming." But in the whole of the English language there is no word to cover the twenty-four-hour period; and many are the difficulties that arise therefrom. We find one in just about the first possible place: the opening chapter of the Book of Genesis.

"And God said, Let there be light: and there was light. And God saw the light and it was good: and God divided the light from the darkness.

And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day."

The terms are no different in Hebrew, and the first chapter of Genesis is one of the oldest stories in existence, older than any records that are left, far older than the remainder of the book, so we can see the emphasis laid upon the division, and the difficulty in expressing it. The anomaly is due to interest; but we are forced to decide upon some arbitrary distinction and in this book we shall speak of "daylight" as the opposite of "night" and let the word "day" refer to the longer period which includes them both, whenever any confusion might arise.

The division between light and dark is not very sharp, even near the tropics, but it did well enough to make a starting or ending point from which the ancient peoples could base their more minute calculations. Daylight furnishes a natural and simple unit; but before the time of clocks, sand glasses, or even water clocks, before any mechanical means were known for marking or recording the passage of time, further subdivision must have been extremely difficult.

Of course the Sun itself provides a kind of scheme beyond just rising and setting. It changes its altitude, for instance, and it moves constantly to different positions in the heavens. The shadow of a tree or a stump made a rough kind of sundial; and later, to facilitate reckoning, pegs were driven into the ground, or lines were drawn around a stump. In very early society, time was, as Sophocles said, "an easygoing god," and short periods were of little importance.

We cannot tell exactly how knowledge grew, as, with a more highly complicated society, the need for precision developed. Lack of documents, and the erosion of even the most solid structures, leaves us very little material from which to base our guess. But with knowledge of what later primitives used, and with the few materials available, at least we can describe a rational and probable procedure.

It seems likely that the plumb line was the earliest instrument used for exact measure. An ancient astronomer could take a leather thong or sinew, attach a stone to the bottom, and, if the day were windless, his crude instrument would furnish him with a vertical line. It required no further testing.

He could also create a right angle by the cut and try method which is still in use. He cut a piece of wood into something resembling a right angle. This he set first one way and then the other against a straight edge, scratching the ground against it, and changing the angle until the scratches coincided. In this way he could create a horizontal line from a vertical; and with these two he had the basis for determining the altitude of the Sun.

With no other means of measuring time except these crude solar instruments, he found the day easier to reckon from sunrise or sunset, than from any vague midway point between the two. With our modern methods we measure from the highest point which the Sun or a star reaches in its passage across the sky. For this purpose we draw an imaginary line, stretching from north to south, directly above our heads, and with reference to this line we reckon the altitude of the heavenly body. At what we call "high" noon, the Sun crosses this line and half its daily journey is complete. Therefore we have named the line "meridian" from the Latin words meaning midday.

On this imaginary line we base almost all of our modern reckonings. Without it, no one can reckon noon, and no one can tell the cardinal points of the Earth. Even today some instruments are necessary, and some calculations must be made, before the line is set; yet for all the seeming difficulties, the Egyptians solved the problem, and solved it with extreme precision, sometime before they began to leave records for our historians. Without a knowledge of the meridian line, they could not have known the exact points of east, west, north and south, yet according to the best modern surveying instruments, their pyramids are set squarely in place. To equal the precision of the orientation of these early monuments, we should have to use good instruments today, and take pains with our work.