THE SOLAR CLOCK

Taranaki Daily News, 16 November 1935, Page 13 (Supplement)

THE SOLAR CLOCK

AMONG CLIFF-DWELLERS

(By the

Rev. B. Dudley,

F.R.A.S.)

So much of the artificial and mechanical has been introduced into modern life, especially in the great cities, that it is hard to realise what we owe to nature. Without intending anything of the sort—without thinking about it even —we have come to regard Nature as something almost independent of the advancement and organisation of human life, as if it had nothing to do with our daily activities. It looks as though he was stating the truth who wrote that “we are becoming so completely fettered by the bondage of mechanical drudgery, so enveloped in the cities’ endless turmoil, that we have forgotten Nature altogether.” So dependent have we become upon the clock, for instance, that we have but forgotten that , the Sun was the original timepiece. And yet there was an enormous period in the history of mankind during which no other means for the measurement of time existed.

Let us-go back in fancy to those remote ages when our ancestors were inspired wholly by Nature in all their daily work. Let us try to picture them out there among the canyons of New Mexico and Arizona, for example, where may yet be found remains of ancient homes built in the hollows an on the ledges of the cliffs. The men who lived in such homes are the predecessors of the Pueblo Indians still existing in these regions. Even those ancient cliffdwellers must have looked up to the sun in worshipful awe, as they watched its passage across the sky from day to day. Visualise the scene—the cliff-dweller going forth to his daily hunt for food; the woman left behind and now and again measuring the length of the day by a glance at the creeping shadows on the cliff’s face, in order to gain some idea fo the time of his expected, return. It was early dawn when he left. But the sun is climbing higher and ever higher in the heavens; and thus the shadow on the opposite wall is steadily moving downwards. The steep cliffs face each other; and while, all the morning, the shadow has crept down the wall on one side until noon, when the whole of the narrow canyon was illuminated by the solar rays, it.now begins to rise on the opposite cliff-face. It is time for the hunter to return with the spoils of his expedition. For he, too, has his shadow-signs, and knows the hour with rough approximation to the truth. And so, ere the shadow has advanced far up the wall opposite the one on which it rested in the morning, the body of the animal tracked and killed has been eaten. These walls were the cliff-dweller’s clock, while the advancing shadow was its tell-tale hand. And so life went on throughout many ages. In due course, devices were adopted. Sticks or stones were planted where there was no tree or rock in such position- as to cast the desired shadows. Throughout succeeding days these poles or stones would mark the points where the shadow fell when the sun was highest in the sky. Thus, for the first time, man has gone beyond the provision Nature has made for him, and he has found an artificial means for marking his time into something like definite intervals. By and by a circle of more numerous stones is made, and a stick, suitably placed, throws a shadow on stone after stone and tells him with still more exactness “the time.” Here is the first sundial—for centuries the forerunner of the clock.

Soon, however, it was found that as the year advanced and the sun went first north and then south, the shadow underwent a change, so that the sundial was at times behind and at other times ahead of itself, so to speak. These shadow-irregularities were got over in the following manner, to borrow the description of a noted writer on scientific subjects. “Berosus,” he states, concerning an ancient Babylonian priest living about the year 250 before tire beginning of the Christian era, “came to the rescue here and hit on a clever way: to get round this trouble caused by the north and south movement of the. sun in the great upside-down bowl of the sky. His pointer was put above with a little round ball on the end, and the time was marked by the shadow of this ball. A vertical pointer, standing upright like a tree, would not have worked; but with this horizontal rod reaching, .out over the bowl he had made he was able to get the desired result. For, however the sun moved, the shadow moved in the bowl just as the sun moved in the arching sky. By an ingenious set of lines of longitude drawn across the bowl, he got a dial or ‘hemicycle’ (half circle) which kept time fairly accurately all the year round.” This was a great step in advance. Throughout the middle ages, too, sundials of various kinds were employed. But what was to be done for the time during the cloudy weather? One of these dials bore the appropriate inscription: “I count but the sunny hours.” Such devices were imperfect enough, and became more and more unsuitable as civilisation moved forward and the need for constancy and accuracy became paramount.

Then came the “Water Thief,” as it was called. The predecessor Of this form of time piece was the water jar, used in China. A somewhat inventive slave, employed in a garden, had placed a jar, with a tiny hole in its bottom, in such position that the water would drip slowly onto a plant situated beneath, instead of pouring upon it all at once. Thus was suggested a kind of time piece, the flow of water being properly regulated so as to indicate time, and workable under all weather conditions. Such time measurers were used in China as far back as 300 8.C.; possibly earlier. The Hindus made use of a copper bowl with a small hole on its underside. The bowl was set afloat in a vessel partly filled with water. Gradually it would sink to the bottom as the water pushed its way up through the tiny aperture. A servant whose duty it was to watch would lift the bowl and, after emptying it, strike it with a rod, perpared for the purpose, so as to notify the household that another time-interval had gone, and then he would set it afloat once more. The “Water Thief” used by the Egyptians and Babylonians was sb constructed that a float was gradually raised by means of water dropping from a hole above. As the float rose it indicated the hour by a scale of numbers marked at the side of the container. Later, by a more elaborate arrangement, a hand was made to turn on a dial as the float ascended. This was the Clepsydra such as Tycho Brahe used in his astronomical observatory at Uraniborg towards the end of the sixteenth century. Tire more mechanical devices in use now are all that can be desired for exactness.