Ye Sundial Booke

by T. Geoffrey W. Henslow

By portable dials I would not have my readers include the tent pole often used by wandering Arabs to cast a shadow, or the possible use of a stone of any size by early man, but the host of small pocket and ring dials made of metal, ivory, wood, or stone that are frequently found in our own land, on the Continent, and in the East.

There is no more engrossing study than the age of the sundial, and to those interested in gnomonics any fresh information or unrecorded history is of the greatest importance. It is, however, left to the excavator of buried cities and ancient ruins of the past to shed fresh light upon such a well-worn subject, and the humble historian but faithfully records and hands down to posterity the result of his discoveries.

The minutes of to-day are as the hours of yesterday, and the necessity of an accurate time-keeper is in this present century more keenly felt than ever it was in the past. A glance at the sky to determine the position of the sun in respect to well-known landmarks may have sufficed the races of primitive man, but as generation succeeded generation, and regular business occupations and more home life commenced, the observance of stated intervals of the day must have become a necessity; so that, if the old proverb be true, necessity became the mother of invention, and in due course gave birth to the sundial, which, as time went on, developed until it reached the perfect stage in which we find it to-day.

Perhaps some day excavations in the Holy Land will reveal fresh forms of horologe that will put into the shade the age of the present dials from ancient Greece, but until then we have little data other than vague allusions to them in the historical records of the past to go upon. It is very doubtful whether ancient Egypt with all its vast learning and resources will ever throw fresh light upon the subject of gnomonics. Situated so close to the Equator, both the horizontal and vertical dials would be of small service.

The angle of the gnomon being equal to the latitude of the place, the few degrees either side of the Equator would necessitate such a small elevation that a horizontal dial would be of little help. Again, a vertical dial would show the time for only a very short portion of the year, since the dial plate would have to be almost parallel with the rays of the sun. Still, doubtless, records may yet be found that will testify to its existence, if not in ancient Egypt, in lands that felt Egyptian influence and benefited by their learning and wisdom.

Theories are problematical and surmises are often without foundation, but I would indeed venture to think that it is more than possible that the sundial played some part in the rectification of the Babylonian calendar in 747 B.C., which took place about nineteen years before the accession of King Ahaz, in whose reign it was clearly alluded to.

The oldest known dials at present are those of Grecian origin, and for the most part are of the hemicyclean form invented by the Chaldean Berosus, who lived about 340 B.C., and his particular shape and construction of dial was in use for centuries. Four of these sundials were discovered in Italy: one at Tivoli in 1746, another at Castel Nuovo in 1751, another at Rignano in 1751, and the fourth at Pompeii in 1762. It is thus evident that this form of sundial which was used by the Arabians (who gave great study to gnomonics) was popular also amongst the Romans. An interesting specimen of this form of horologe, which can now be seen in the British Museum, was found at the base of Cleopatra’s Needle in 1852. This dial is concave, and is made from a stone 16½ inches high by 17 inches wide, the depth of the bowl being 10 inches; the hours marked are the twelve unequal hours by which the Greeks divided up their day.

This dial—by no means satisfactory—doubtless owed much of its popularity to its novel construction, and to the fact that it was more or less of a portable nature. But the knowledge that it was constructed 360 years after the known existence of the sundial (see Isaiah xxxviii. 8), leads us to surmise that other forms of dials were in use at the same time. It is a known fact that the ancients were familiar with declining dials, and the Tower of the Winds at Athens, which still exists, has on its walls, built in octagonal shape, no fewer than eight of this kind. And although the date of these dials is evidently of a later period than the actual building, they certainly belong to a very early time. However, the Greeks were, as we know, well versed in the art of dialling, and without doubt gave a lead in this study to other nations.

Herodotus, writing in 443 B.C., says that the Greeks acquired their knowledge of the sundial from the Babylonians; the Roman writers in turn give evidence of their acquisition of this instrument from the Greeks. Although the Romans were backward in the science of gnomonics and slow to adopt any particular form of horologe, they eventually constructed many a beautiful dial of varied design. The first sundial was erected in Rome in the year 290 B.C., this being taken from the Samnites by Papirius Cursor. Another was brought to Rome by Valerius Messala from Catania 261 B.C., but it was not until 164 B.C. that, as far as we know, a dial constructed at Rome was set up by order of Q. Marcius Philippus.

Cicero, writing in 48 B.C. to Tiro, mentions that he wished to place a sundial at his villa in Tusculum, and at a later date we see Romans erecting sundials in every possible corner of their villas and grounds.