Operating Instructions for Geochrons
Congratulations on purchasing the unique Geochron World Time Indicator. Please take a few minutes to read these instructions and avoid damage to your Geochron.
How to set your Geochron
After you have unlocked, mounted and plugged in your Geochron, set the correct time and date, etc., as follows:
Visual shift in time scale. Top scale = Daylight savings time; bottom scale = Standard time.
Day of Week and Time
Pull down the aluminum knob located underneath and to the right of Geochron.Turn until the prevailing day of week in your locale show on the map near the dateline.
Pull down and turn knob until your zone arrow points to your time on the time scale above the map.
Calibrations are five minutes, A.M. is to the left and P.M. is to the right of the Noon line. Set about 1 minute fast to allow for backlash.
Minute Indicator (on the Original Kilburg Model)
Turn the small knob above dial on top of Geochron.
Calendar and Sun
The knob in the middle, underneath the Geochron sets the calendar and its associated sun, sunrise and sunset mechanism. Turn it clockwise. In operation, the calendar moves imperceptibly from East to West (relative to map).
When it is midnight at the International Date Line, the calendar indicator lines should match with the lines between two dates on the calendar.
When it is noon at the International Date Line, at the time the calendar is being set, the indicator line should be half way between the calibrating lines of the calendar.
There are two calendar indicator lines. To read the date on the right of the date line, use upper indicator; to the left use the lower indicator.
Lighting
The light in the Geochron may be left on continuously. It may also be turned off for any reason. The Geochron will continue to indicate correct time but will not show the daylight pattern.
Scientific Information
The Principal Objective of the Geochron
The principal objective of the Geochron is to provide a device capable of pictorializing, on a flat surface, global solar time and its modifications as well as related natural phenomena. Specifically, the Geochron displays the following:
- Legal Zone Time
- Greenwich Mean Time
- Greenwich Apparent Time
- Local Apparent Time
- Moment of Sunrise
- Moment of Sunset
- Duration of Daylight
- Sun's Meridian Passage
- Sun's Equation of Time
- Degrees Latitude
- Degrees Longitude
- The Geographic Extent of the Prevailing Day and Date
A Brief Introduction to Solar Time, its Modifications, and Related Facts
The basis of daily time measurement is the relationship of the earth's surface to the sun. Thus, when the earth makes one revolution about its axis relative to the sun, it is said to be one day. However, the speed of the earth's travel around the sun varies so that over a period of one year, some days are shorter and others longer, causing the relative zenith, or noon position of the sun to vary accordingly. This is what is measured by a sun dial - "apparent solar time."
For time measurement purposes, man has taken the "mean" between the longest and the shortest apparent solar days, divided it into 24 equal hours, and thus made "mean solar time." When our clocks say 12 o'clock "mean time", it does not necessarily indicate that the sun is at its zenith. For the largest part of the year, there is a difference between "mean noon" and "apparent noon", and this difference is called the "equation of time."
One's location in longitude within a time zone also affects the relationship between "apparent noon" and "legal zone time noon." The geographic extent of a given day is determined by the position of the international dateline (180 degrees meridian of longitude) relative to the "mean sun" or "mean noon." For example, if the international dateline coincides with the "mean sun" (mean noon), half of the earth's surface is today and the other half is tomorrow; or yesterday, depending on which half one's position is. Thus, there are two different week days and dates at any given moment, except for an instant each day when it is midnight at the dateline. At this point of time, the same day exists around the earth.
"Zone time" is, or course, the designated time for a given area measuring, ideally, 15 degrees in longitude, having a standard meridian central to the zone. In practice, however, legal zone boundaries are highly irregular and nonconforming. Further distortion of "ideal" zone time occurs where daylight savings time is used.
The time of sunrise and sunset is influenced by one's position in latitude, due to the 23 1/2 degrees tilt of the earth relative to its orbital plane. It also varies due to the changing speed of the earth along its orbit around the sun. For example, at the equator, the time of sunrise and sunset varies 30 minutes over a period of one year, (same as equation of time) while the actual daylight period remains nearly constant.
Sun's View of Earth / Design Consideration of the Geochron
The information shown by the Geochron is displayed on a flat surface rather than a globe because only a limited legible area is seen when glancing at a globe.
The instrument is normally hung from the wall. To permit recess mounting, its depth is based on the 3 1/2" width of a standard wall stud. Thus, the Geochron can be surface or flush mounted. Both methods are also designed to prevent accidental dropping of the instrument.
The length and height of the Geochron are governed by the fact that one inch of longitude on the map is equal to one hour, and that 75 degrees north latitude and 66 1/2 degrees south latitude cover all areas of time-telling importance.
The Geochron's appearance is intended to be simple, devoid of apparent controls and knobs, and its finish is adaptable to any decor.
The fluorescent tubes, starters and ballasts used in its internal illumination are accessible and replaceable without dismantling the unit.
Principal Components and Systems of the Geochron
The map, time band, calendar band, and day of the week band system
The map is an endless Mylar belt upon which are printed three continuous maps of the world, together with legal time zone boundaries and arrows. At the seams, the ends are joined by a special Mylar adhesive tape. The map is translucent and has sprocket holes at the lower edge. It is engaged by sprocket wheels which are part of the roller assembly supporting the map. One sprocket wheel has a molded gear on its underside which is engaged by the map drive motor assembly.
The sprocket wheels also engage the day of the week band, which is also a Mylar belt, seven times the length of one world map, and has printed upon it the names of the days of the week. Because of its length, the belt is trained over a series of take-up rollers.
The map belt surrounds the Geochron mechanism and frame structure, as well as the day of the week band, so that the day names show through the clear area adjacent to the dateline on the map belts lower edge. When the "synchronous map motor" drives the sprocket wheel, the map belt and the day of the week belt are driven in unison at a speed analogous to the speed of rotation of the earth. Above the map belt is the time belt. It is also a Mylar belt in order to maintain the same expansion or contraction as the map. Its position is fixed with the top scale indicating daylight savings time and the bottom scale standard time. In operation, the arrows on the map point to the time band scale which is calibrated to five minutes. The map moves from left to right while the time band stands still.
The "map motor assembly" has a shaft extending downward, at the end of which is a knob. It projects from the underside and extreme right of the Geochron. When pulling down on the knob, the shaft disengages the motor and permits the manual operation of the map drive. This provides manual setting of the map, like setting a watch.
Below the lower edge of the map is the "calendar band." It is also an endless Mylar belt with sprocket holes engaged by the sprocket wheel on a "mechanism carriage". The length of the calendar belt is the same as the map belt. Its support rollers are part of the roller assembly to the left and right of the frame structure.
The sun, sunrise and sunset system has a "mechanism carriage" supported by four rollers. Its horizontal movement is governed by a cam held by a spring against a stationary cam roller. This cam makes one revolution per year and imparts a horizontal shift to the carriage equal to 30 minutes on the map and analogous to the "equation of time."
As a result of its simultaneous, horizontal, and vertical movement, the sun button describes a figure eight pattern, crossing the "mean noon" four times. The pattern is called the "analemma."
The Analemma
Geochron has a red line coinciding with the 12 o'clock noon marking on the time band. It provides a reference from top to bottom of the map indicating "mean noon." The sun button's horizontal movement relative to this line indicates the meridian passage of the sun and the "equation of time."
A slot in the vertically slideable actuator plate, in the back of the mechanism, engages a crank roller secured to the aforementioned cam. The slot is slightly curved to compensate for the non-uniform vertical movement of the "apparent sun". The circular movement of the crank roller drives the actuator plate and provides for the progressive increase and decrease of the declination of the sun.
The mechanism carriage also supports the sunrise and sunset delineation reeds. These are two flat spring steel bands with one of their edges contacting a light diffusing panel. Each is secured at its center to a reed carrier, fastened to a shaft. At both ends, each reed is held by a slotted button set into both ends of a Plexiglas lever. Central to the location of its two slotted buttons, the plexiglass lever is mounted to a hub which, in turn, is secured to a hollow shaft.
The central reed carrier shaft is supported by bearing inside the hollow shaft, which have a common center and means of support in the mechanism carriage.
Both the hollow shaft and the central reed carrier shaft protrude from a main support bearing toward the cam (rear) side of the mechanism carriage. Each shaft has a slotted lever secured to its protruding end. A slot in each lever is engaged by a pin projecting from the vertically slideable actuator plate. The length of the central reed shaft lever is about twice that of the hollow shaft lever, while their respective drive pins, as secured to the actuator plate, move the same vertical distance. As a result, the radial motion imparted to the hollow shaft is greater than that of the central reed shaft.
Consequently, as the actuator plate is driven upward or downward from its central position, the reeds bend gradually from straight line into a "S" shape and reverse.
The reeds are "tuned" by special fabrication, to bend in the proper places conforming to the plotted curves delineating sunrise and sunset on a Mercator Projection map in accordance with Nautical Almanac's sunrise and sunset tables.
Associated with the reed carriers are blue light filters whose shape has been developed to produce a dark effect to one side of the reeds while the area between the two reeds is illuminated.
The distance from the diffusing panel contact the edge of the reeds and the plane of the light filters in such a way that the fixed contours of the filters do not alter the sharp delineation of sunset and sunrise produced by the reeds.
The sun, sunrise, and sunset mechanism system is driven by a synchronous motor coupled to a gear train which reduces the speed to one revolution per year.
There is also a sprocket wheel connected with the gear train. It is located near the calendar belt so as to engage its sprocket holes. Thus, as the gear train turns, the calendar belt moves in proper relation to the changing sunrise and sunset, as well as the relative position of the sun. The gear clutching system permits the clockwise manual setting of the mechanism.
The Illumination System
In normal light, the Geochron is illuminated from within, in order to display where the sun is shining and darkness exists. For this purpose there are two fluorescent tubes with ballasts, starters, and a light switch.
Geochron Technical Information - Overview
An Introduction to World Time with the Geochron - Man's Natural Timepiece
From the first crude sundials that divided the days into vague and irregular intervals, to the finest navigational chronometers that maintain split-second accuracy over long periods, our basic source of time has always been the rotation of the earth we live on and the apparent motion of the sun that this rotation causes. Even before any concept of time existed, the daily alternation of light and darkness must have regulated man's activities, as it does the activities of animals today. As recently as one hundred and thirty years ago, every city, town and hamlet on earth observed its own local time based on the instant that the sun reached its zenith at that locality, and "high noon" was the universal time for setting clocks and watches.
The Time Zone Problem
Those simple and straightforward days of Local Sun Time ended when the first transcontinental railroads ushered in the era of modern long-distance transportation. The time confusion for travelers and railroad workers became so great on long trips that in the 1870s the 24 "standard" world time zones we know today were set up by international agreement. These zones solved one problem but created another. Today, in our age of high speed jet travel, electronic communications, and growing international involvement, more and more people need to know, or are interested in knowing, what time it is somewhere else - often halfway around the earth. The problem that time zones created is that the ordinary clock and watch are highly inadequate for telling time on a global basis.
The Inadequacy Of The Clock
Conventional clocks are essentially local time indicators and no more. (The last basic innovation in the design of clocks - outside of improved accuracy and minor gimmickry - was back in the 17th century when someone added the minute hand to the theretofore single-handed clock dial.) Because clocks and watches present time as an abstract (and sometimes meaningless) number, learning the time in another part of the world is a matter of working with other abstract numbers (time zone conversion factors) as well as figuring out whether it is A.M. or P.M., what day of the week and what date it is. Since there are at least 34 local world time zones (24 standard and 10 nonstandard) the problem is not simple. And, for this same reason, the idea of multiple dials or clocks for keeping track of world time is impractical.
Geochron: The New World Timepiece
Geochron solves all these problems in one stroke by combining the answers to the two questions "What time?" and "Where?" in a single easy-to-read graphic analog. Physically, the Geochron looks like a framed world map, about 1 metre by 0.6 metres in size. It is designed to be hung on the wall. The colourful map itself, a precision Mercator projection printed on dimensionally stable Mylar, is an endless belt that is driven slowly from left to right by an electric clock motor in synchronism with the rotation of the earth. All known legal time zone boundaries are delineated on the map by dark blue lines which, in most cases, converge on lettered pointers on the top edge of the map. These letters identify the standard time zones and also represent the short-wave radio prefix for that zone.
Reading World Time On Geochron
The time zone arrows point to a stationary time scale across the top of the map that reads from midnight to the left, through noon in the middle, to midnight again at the right. To read the time in any standard zone in the world, you simply find that place on the map and follow the zone boundaries to the arrow which points out the correct time. Certain non-standard and pocketed zones have boundaries that do not extend to an arrow. These are marked with a letter and a number. The letter tells you which arrow to read and the number shows the deviation from standard time. In the case of India, for example, the designation is E + 30. This means that you add 30 minutes to time you read on the E-pointer. Simple addition of a fraction of an hour in the case of the 10 non-standard zones is the only calculation ever required in reading the Geochron.
Reading the Date and Day of the Week on the Geochron
Since the map is moving slowly across the frame from left to right, the International Dateline crosses the frame once each day. The days of the week observed on either side of the Dateline are displayed in windows near the bottom of the map. The date and month for these two days are likewise shown on an indicator mounted at the bottom of the Geochron.
The Geochron: Graphic Analog of Day and Night
Perhaps the most fascinating thing about the Geochron is that it shows the exact portions of the earth that are in daylight, and those that are in darkness, at the very instant you are observing the Geochron. The brightly illuminated pattern in the center of the map delineates those areas that are in daylight. The left edge of this pattern is the line of sunrise as it sweeps across the earth, and the right edge is the line of sunset. Because the length of the day is changing daily as the earth progresses through its seasons, the light pattern on the Geochron changes also, almost imperceptibly, from day to day. Thus, with the Geochron you can read the time of sunrise and sunset and the relative length of day and night for any latitude.
This illuminated pattern also shows the progress of the seasons during the year, from winter through spring, summer, autumn and back to winter again. These previously abstract phenomena (the summer and winter solstices on the dates of the longest and shortest days of the year, and the vernal and autumnal equinoxes, when the day and night are of equal length) are clearly and graphically shown by the Geochron light pattern.
Because the Geochron is a graphic analog, the viewer soon gains an instinctive appreciation of what time it is everywhere. It no longer becomes necessary to read an abstract number to know if it is an appropriate time to call someone in Paris, France, or Sydney, Australia. A glance at the light pattern on the map instantly tells you whether it is daylight at those places or the middle of the night.
Other Uses for the Geochron
The Geochron is provided with two simple basic controls that allow it to be used for far more than just telling time. One knob at the base of the unit allows you to move the map horizontally across the frame. It is used basically to set the correct time on the Geochron scale when it is first plugged in. But, by moving the map, you can also determine the time of sunrise and sunset at any locality on that day and see the relative effect of latitude on these times.
The second knob at the base of the unit allows you to set the date indicator to any day of any month in the year. Since the light pattern mechanism is coupled to the date indicator, this also changes and shows the light condition on earth at that time of year. This feature has been found valuable by educators, motion picture producers, military men, as well as by the average person who just wants some help in planning his holiday.
The Geochron also shows the exact zenith position of the sun at any time on any date and graphically indicates the relationship between Apparent Solar Time and Mean Solar Time as expressed in the Equation of Time. This is indicated by a small black dot that follows the zenith position of the sun as it traverses the earth.
The Geochron: Modern Successor To The Wall Clock
The Geochron is the new world timepiece for those in business, government or private affairs whose timetelling needs or interests extend beyond the boundaries of their own local time zones. It can truly be called the modern successor to the wall clock in this modern age of high-speed international travel, communication and world involvement.