Time Telling through the Ages

Sandoz and Trot – A firm which established the first watch factory in Switzerland in 1804. Previous to that time watchmaking had been a house industry.

Second – One-sixtieth of a minute: 1-3600 of a mean solar hour.

Secondary Compensation – Same as "auxiliary compensation." See Auxiliary (#Auxiliary).

Seconds Hand – The hand on the dial of a clock or watch which revolves once a minute. Sometimes small and set in a small circle of its own. Sometimes long and traverses the whole dial. See Center-seconds and Sweep-seconds (#Center_Seconds).

Seconds Pivot – The prolongation of the fourth wheel arbor to which the seconds hand of a watch is fixed.

Seconds, Split – Divided seconds – into quarters, or fifths; measured by a chronograph.

Shadow – A darkened space resulting from the interception of light by an opaque body.

Shagreen – Made from the tough skin that covers the crupper of a horse or ass. Rough seeds are trodden into the skin and then allowed to dry. The seeds are shaken out and the skin dyed green. Then the rough surface is rubbed down smooth leaving white spots on the green ground. Also made from the rough skin of sharks and dolphins. Formerly used a great deal for the outer cases of watches. See Pair Cases (#Pair_Case).

Sherwood, Napoleon Bonaparte – Born in 1823. About 1855 he entered the watchmaking business in the employ of the Waltham Watch Co. He revolutionized jeweling methods and invented among other things a "Counter-sinker," "End-shake tools," "Truing-up tools" and "Opener." In 1864 he organized the Newark Watch Company but within a few months severed his connection with it. He died in 1872.

Sidereal Time – The standard used by astronomers; measured by the diurnal rotation of the earth, which turns on its axis in 23 hours, 56 minutes, 4.1 seconds. The sidereal day is therefore 3 minutes, 56 seconds shorter than the mean solar day. Mean time clocks can be regulated with greater facility by the stars than by the sun for the motion of the earth with regard to the fixed stars is uniform. Clocks all over the United States are so regulated from the Naval Observatory at Washington.

Side-Shake – Freedom of pivots to move sideways. See End-Shake (#Page_267).

Slow Train – A train whose balance vibrates 14,400 times an hour. Now never used in pocket watches because of susceptibility to inequalities in the pull of the mainspring, jars, sudden movements, etc. Used, however, in marine chronometers.

Snail – A cam shaped like a snail, used generally for gradually lifting and suddenly discharging a lever, as in the striking mechanism of clocks.

Snailing – A method of ornamenting with circles and bars parts of a watch movement which it is not desirable to polish highly.

Solar Time – Time marked by the diurnal revolution of the earth with regard to the sun, of which the midday is the instant at which the sun appears at its greatest height above the horizon. This instant varies from twelve o'clock mean time because the earth also advances in its orbit and its meridians are not perpendicular to the ecliptic.

Spandrels – The corners of a square face outside the dial of a clock. Formerly very beautifully decorated. The age of the clock can be told approximately from the form of ornamentation employed.

Split Seconds – A chronograph in which there are two center-seconds hands – one under the other – which can be stopped independently of one another.

Spring-Clocks – Clocks whose driving power is a coiled spring instead of a weight.

Stackfreed – The derivation of the word is obscure; it is possibly Persian. A device to counteract the difference in power of the mainspring at the different stages of its unwinding. Fixed to the mainspring arbor above the top plate is a pinion having eight leaves, which gears with a wheel having twenty-four teeth, which do not quite fill out the circumference of the wheel. Fastened to the wheel is a cam, concentric for about seven-eighths of its circumference and indented for the remainder. Into a groove in the concentric portion of the edge is pressed a roller which is pivoted at the free end of a strong curved spring. When the mainspring is fully wound the roller rests in the curved depression of the cam and the effort required to lift the roller up the incline absorbs some of the mainspring's power. On the other hand when the mainspring is nearly run down, the roller is descending an inclined plane and absorbs less of the power. Not an acceptable device and now rarely met with.

Stem-Winding – The ordinary method of winding keyless watches by means of a stem running through the pendant.

Stop Work – An arrangement for preventing the overwinding of a mainspring or a clock weight.

Stratton, N. P.– One of the early watchmakers connected with American manufacture. He was an apprentice of the Pitkin Bros., and was sent by the Waltham Company to England in 1852 to learn gilding and etching. He was made assistant superintendent of the Waltham Co. in 1857. He invented a mainspring barrel and a hair-spring stud which were later adopted by the Waltham Company.

Striking-Work – The part of a clock's mechanism devoted to striking. The chief forms are Rack (#Striking_WorkRack), and Locking-plate, or Count-wheel (#Striking_Work_Locking_Plate_or_Count_Wheel). See separate articles.

Striking-Work, Locking-Plate, or Count-Wheel – Used in turret clocks where there is no occasion for the repeating movement. This form of striking work does not allow of the repetition or omission of the striking of any hour without making the next one wrong.

Striking-Work – Rack – A form of striking work used largely in house clocks; the number of blows to be struck depends merely on the position of a wheel attached to the going part. In this form the striking of any horn may be omitted or repeated without deranging the following strikes.

Stud – 1. A small piece of metal pierced to receive the outer or upper coil of a balance spring. 2. The holder of the fusee stop-work. 3. Any fixed holder used in a watch or clock, not otherwise named, is called a stud.

Style – The finger or gnomon on a sun-dial whose shadow, falling on the plate, indicates the time.

Sully, Henry – An English watchmaker of the early eighteenth century who lived most of his life in France. He presented the French Academy with a marine timekeeper superior to the timepieces of the period, and a memoir describing it. He died shortly afterward and advance in the art was delayed.

Sun-Dial – A device for telling time by the shadow of a style, cast by the sun, as thrown upon a disk or plate marked with the hour lines. Dials were named from their positions – equinoctial or equatorial; east; erect or vertical; horizontal; inclining, etc., or from their purpose or method of use, as portable, reflecting, etc., or as in the case of the ring-dial, from their form. The word is derived from the Latin dies. The style in the earliest dials was a vertical staff, but later it was found that reasonable accuracy could only be obtained by a style set parallel to the earth's axis – that is, inclined to the horizontal at the angle of latitude of the locality in which the dial was set.

Even before the first astronomical discoveries of the Babylonians, people had felt some need of a convenient device to mark and measure the passing of the time, especially the shorter divisions of recurring time, the time of day. Sunrise and sunset marked themselves by the horizon, but noon was harder to determine, and the points of mid-morning and mid-afternoon harder still. And with the knowledge of those regular movements in the heavens which determine time on earth, and with the closer division of the day into its hours, that need became a sheer necessity.

The obvious measure of the sun's movements was the moving shadow cast by the sun itself. And the earliest device for recording time was naturally the sun-dial. Its origin fades into the twilight of antiquity. Long before we know anything about him, primitive man measured the moving shadow of some tree. And it occurred to him to set up a post or pillar in some convenient place, and mark out the positions into which the shadow swung. The earliest sun-dials were of this pattern, with a vertical pointer of gnomon, and the hours marked upon the ground. And it is related of the early Greeks that they told the time individually by marking and measuring the length of their own shadows. But the measure of time by the length of a shadow is very irregular at best, because of the yearly motion of the sun. The shortest shadow of the day will indeed fall at noon. But that noon shadow will vary in length according as the sun's noon is high in Summer or low in Winter; and so the whole scale of lengths will be different for every day in the year. If a three foot shadow means mid-afternoon today, it will mean quite another time tomorrow. And for measuring by the direction of the shadow, the vertical gnomon is more irregular still. For the swing of the shadow would depend not only upon the sun's motion across the sky from East to West, but also upon his slant North and South along the sky. And this would change from day to day. The difficulty was to make a dial of which the shadow would move as regularly as the sun moves.

ANCIENT GREEK HEMICYCLE

This the ancients accomplished in a very simple and ingenious way. The sun moves in the sky as it were upon the inner surface of a hollow globe or sphere. So they made the dial a little hemisphere, place with its hollow side up toward the sky as a bowl stands on a table. The pointer was placed above and to the South of this, on the side toward the sun; and the Time was marked by the shadow of the tip end of the pointer which was a little ball or bead. The path of this shadow across the bowl reproduced exactly on a small scale the path of the sun across the great bowl of the heavens. And it was then an easy matter to mark off the bowl into equal divisions which the shadow would cross at equal intervals of the day. Of course, the track of the shadow changed with the season of the year. But it moved always as the sun moved, and just as regularly, giving a true measure of the solar day.

The principle of this was applied in several interesting variations. The defect of the Hemicycle, as this hollow type of dial was called, was that it could not be read accurately for short intervals. A shadow moving only a few inches in the whole day must move so slowly that one could hardly see it move at all. To mark the minutes, it must move faster, just as the minute hand of your watch moves faster than the hour hand, and the second hand faster still. One cannot read seconds from the hour hand, however accurately it moves, because it moves so slowly. So the idea was applied by making the shadow move across a street or courtyard, down one side and across and up the other side, as the sun opposite went up and across and down the sky. Sometimes the place was partly roofed over, and a single beam of light admitted through a small hole at the South end. The resulting spot of light would then move in the same way. The long sunbeam or shadow moved faster, and so could be read at shorter intervals. The Hemicycle is not certainly known to have been invented until long after this, about B. C. 350. But the principle of it is so simple and so entirely such as would occur to an intelligent man still ignorant of its mathematical explanation, that we may not unreasonably suppose it to have been discovered by experiments long before.

ANCIENT ROMAN HEMICYCLE

The final improvement of the sundial was the discovery that by slanting the gnomon so that it pointed exactly toward the North Pole of the sky, the direction of its shadow could be made to show the solar time correctly. Since the sky is infinitely far away, the line of the gnomon would then lie parallel to the axis of the heavens. And the sun, moving parallel to the celestial Equator, would always move straight across the gnomon. In other words, he would practically revolve around its sloping edge. Therefore the North and South motion of the sun would be as it were along the edge of the gnomon, and would not influence the direction of the shadow at all. His East and West motion alone would govern the swing of the shadow; and the dial would keep true time with the sun for every day in the year. There was no longer any necessity for hollowing out the dial itself into the concave form; it might just as well be the more convenient flat surface, and this might be either vertical or horizontal, so long as the gnomon pointed straight to the Celestial Pole. All that was needed was to mark out on the dial the true direction in which the shadow fell for each hour of the day.

OLD ENGLISH DIAL

Just when or by whom the instrument was thus scientifically perfected is not known. The calculations necessary to the projection of the hour lines upon a flat surface could hardly have been performed before Greek times. The Greeks ascribed the invention of the sundial to Anaximander, in the sixth century B. C., but sundials of various types had been known in various parts of the world long before then. On the other hand, the Hemicycle remained the common form of the instrument all through the classic period and even afterwards. The Babylonians were quite capable of understanding the principle of the sloping gnomon. And once this was discovered, it would have been entirely practical to set up the new dial beside a Hemicycle or Clepsydra, and find the angles of the hour lines by experiment. These, once laid out correctly, would be determined once for all. Even at its best the sundial had certain very marked limitations. Scientifically constructed, it would keep accurate time according to the visible sun. But it could not be read accurately unless made inconveniently large. It was inaccurate when removed from its original latitude, or displaced from a true North and South position; so that in any portable form it became a very rough measure indeed. Moreover, it was of course entirely useless at night or in bad weather or in shadow. And finally, it was never absolutely exact under the most ideal conditions, because of what is known as the Equation of Time. The Earth does not, in fact, move around the sun at an absolutely regular rate of speed; it moves a trifle faster during certain parts of the year and slower at others. The sun therefore varies correspondingly his apparent speed along the Ecliptic, so that even from noon to noon the sun is not always precisely on time. He may be as much as fifteen minutes late or early, according to the season. And our modern days are measured according to the sun's average rate, so as to allow for this variation and keep every day exactly twenty-four hours long. This of course no sun-dial can possibly be made to do, since it must follow the actual sun.

The sun-dial has remained in use to the present day. It seems strange to think of a sun-dial being used as a standard for setting clocks and actually to regulate the running of trains. But these things were done in civilized Europe within the last half century. It was only when the railroad and the telegraph had made standard time at once necessary and easy to obtain that the sun-dial altogether lost its position of authority.

Sun-Dials, Descriptions – Classical sun-dials were of many forms. Vitruvius, the Roman engineer, mentions thirteen, some of them portable; and ascribes the invention of the Hemicycle to the Babylonian astronomer and priest, Berosus. There was a famous dial of this type at the base of Cleopatra's Needle in Egypt. It is now at the British Museum. And the Emperor Augustus, returning from his Egyptian wars, brought home to Rome an obelisk which he set up as the gnomon of a huge dial in the Campus Martius. At Athens there was the famous Tower of the Winds; octagonal in shape, with a weather vane above, and below around the tower, the hours and the winds, to each of which the Greeks gave a personality and a name. There is a curious bit of accidental poetry in the marking of the sun-dial in Greece. The Greek numerals, like the Roman, were simply the letters of their alphabet arranged in a certain order. The hot hours of the day from noon to four o'clock were those commonly devoted by the Greeks to rest and recreation. Reckoning the day from sunrise, this period ran from the sixth hour through the ninth. And the numeral letters for Six, Seven, Eight and Nine, which marked those hours upon the dial, spell out the Greek word ΖἩΟΙ, the imperative of the verb to live. The poet Lucian thus points the moral:

Six hours to labor, four to leisure give;
In them – so say the dialled hours – LIVE.

The shepherds of the Pyrenees still consult their pocket dials. And the Turk makes a sun-dial of his two hands by holding them up with the tips of the thumbs joined horizontally and the forefingers extended upward; so that the shadow of one forefinger falls toward the other and by its position roughly indicates the time. But even now, when it has nearly gone from practical use, the sun-dial, as an appropriate adornment of our public parks and our private gardens, is becoming increasingly fashionable in our own generation.

OLD FRENCH WALL DIAL

Sun-dials are common in almost all parts of the world, and not a few of them have in one way or another become famous. The largest is at Jaipur in India, and was erected about 1730. Its gnomon is ninety feet high and one hundred and forty-seven feet long. A flight of stone steps run up the slope of it, and at the top there is a sort of little watch-tower. And the shadow, which falls upon a great stone quadrant instead of upon a flat surface, moves at the rate of two and a half inches a minute. Another great dial is the so-called Calendar Stone of Mexico, which was made by the Aztec priests more than a hundred years before the Spaniards came. It weighs nearly fifty tons, and is not only a sun-dial but a representation of the zodiac and a diagram of the astronomical changes of the year: thus showing that the ancient Mexicans in their own way paralleled the astrology of the Babylonians on the other side of the world. Probably the most expensive and elaborate sun-dial ever built was the one set up in 1669 by King Charles II of England in front of the banqueting house at White Hall in London. It was in the form of a tall pyramid on which were two hundred and seventy-one different dials, giving not only the hour of the day but various astronomical and geographical indications as well. The place called Seven Dials in London takes its name from a tall pillar with sun-dials around its top which used to stand at the junction of seven streets radiating starwise from that spot as a center. The pillar was overthrown in 1773 by a party of vandals digging for buried treasure which they believed to have been hidden beneath its base. Extensive list, descriptions and illustrations, See Book of Sun-dials, Mrs. Alfred Gatty; Sun-dials and Roses, Mrs. Alice Morse Earle.

OLD ENGLISH PILLAR DIAL

Sun-Dials, Greek – 1. Diogenes asserts that the first Greek dial or gnomon was erected by Anaximander of Miletus. It was probably a vertical rod on a horizontal plane. This was two centuries after the Dial of Ahaz. 2. On the "Tower of the Winds" in Athens – a dial on each face.

Sun-Dial, Hollow – A form of sun-dial invented by the Chaldean Berosus. A hollow hemisphere with a bead at its center, whose shadow indicated the hour of the day.

Sun-Dial, Mottoes – On nearly all sun-dials both ancient and modern there there is inscribed a motto – usually of the moral significance of the passage of time.

Very ancient also, as well as equally common in modern times is the custom of placing upon the sun-dial some appropriate motto expressive of the mystery of Time. There are hundreds of such mottoes, ranging in sentiment from the old Roman one: Horas non numero nisi Serenas. "I number no hours but the fair ones," to the couplet of a modern poet:

"Time flies, you say? Ah no,