TGM Time

Time is the fundamental basis for TGM, rather than length as is the case with the SI metric system. As such, it's important that TGM's definition of time be clear, unambiguous, and based upon something that's easily recognizable and familiar to everyone. That one thing is the mean solar day.

The Mean Solar Day

The mean solar day is the average length of the day; that is, the average time it takes for the Earth to make one full rotation, or to put it another way, the average time it takes the sun to get from one point in the sky back to that same point. Truly, of course, the actual solar day as we experience it is variable; in some places, indeed, it varies extremely, as above the Arctic circle (and below the Antarctic circle) day and night are each about six months long. The vast majority of humanity, however, experiences something quite close to what we call the mean solar day; and even those who do not have bodies and natural cycles that are built irrevocably upon the mean solar day. Even the Inuit, after all, normally sleep once per day, even if the sun does not set for them.

The Hour

So Tom Pendlebury, the original creator of TGM, fixed upon the mean solar day as the basis for his new metric system. He also noticed that our current division of the day into hours is itself a dozenal division. We divide the day into two units of twelve hours each. If we consider the entire mean solar day as a circle, we can divide that circle into two; each half-circle is then divided into twelve constituent parts, which we call "hours." (This matches up well with the TGM division of the circle, fixing all our problems with irritating notation for radians and inconvenient numbers of degrees.) This gives us a day divided into 20 (two dozen, or two unqua; decimal twenty-four) hours. Each hour is itself divided into twelve units; these are our familiar units of five minutes each, though now they actually make sense. In our decimal system, the twelfth of an hour seems awfully arbitrary, just as the hour itself does; why twelve, when we're so accustomed to ten being the basis for everything? But in dozenal, all of these fits together beautifully; we can name the time up to increments of five minutes simply by stating a normal dozenal fraction, equivalent to saying "10.5 o'clock" for half-past ten in decimal; except, of course, that this is dozenal, and we have many more convenient, short, regular fractions that we can easy put together.

Twelve noon is "10 o'clock" (that's onequa o'clock, or one dozen o'clock); half past is really half past, at six (which is half the dozen); we can easily speak of thirds and quarters of the hour without having to mentally convert into decimal when we want to write down the number of minutes (a quarter of an hour is decimal 15 minutes; a third of an hour is decimal 20 minutes). Simply put, we can declare the time as a basic, run-of-the-mill dozenal fraction. Half past seven is "6;7"; a third past two is "2;4"; a quarter till ten is "9;9." These are just fractions, normal and unremarkable. Nine and a half is "9;6"; so half past nine o'clock is "9;6."

More granularity in the division of the hour can certainly be obtained. Typically, for daily use in decimal we give the time in hours, minutes, and seconds; this is really a mixed dozenal/sexagesimal (base 60) system, all expressed in the decimal base just to make things difficult. In dozenal, though, we get greater precision for the same number of digits. Divide each twelfth of an hour (a period we now know as five minutes) into twelfths itself; this yields a period of twenty-five seconds (21 in dozenal); so giving two digits of the fraction of the hour rather than one gives us units of twoqua-one seconds each. So "9;66" is "09:32:30" in the old reckoning; in dozenal, of course, it's just half past nine, then half way from the 6 to the 7 on the clock.

The Tim

All this playing with the hour is certainly fun and useful, but at some point we must come to the basic TGM unit of time. We've already divided the hour, an even dozenal fraction of the mean solar day, into twelve units of five minutes each; these are, of course, simply unciaHours (see SDN in Brief if you don't understand this notation). We've also divided those five-minute-long unciaHours into twelve units each; these are, of course, simply biciaHours. If we divide biciaHours into twelve, we get triciaHours, each to 2;1 seconds each; and if we divide triciaHours into twelve, we get quadciaHours, equal to 0;21 seconds, or about 0.17361 seconds. This unit, a trifle more than a sixth of a second long, is the basic unit of time in TGM, and we therefore give it its own name: the Tim.

Since this is our basic unit, we define these other units we've been discussing in terms of it: e.g., an hour is a quadquaTim, five minutes is a triquaTim, and so on. Since the second is the typical SI basic unit of time, most comparisons we make in this article will be at least partly in terms of seconds and Tims.

The table above gives some common comparisons of Tims to units we run into regularly in our lives, along with comparisons to seconds. All seconds figures are in decimal; all others are in dozenal.

Of course, in our day-to-day lives we won't want to be using Tims much, unless we're talking about a photo-finish in a race, computer performance times, or something similar. Rather, we'd want to talk about hours and unciaHours and biciaHours and the like. Among those who use TGM on a regular basis, certain colloquial expressions for these terms have arisen. Furthermore, the Tim itself has acquired an affectionate nickname for when its services are required. Decimal equivalents are in decimal and sometimes approximate.

It thus becomes quite easy to say something like, "I'll be out in a block," or "Give me two blocks," or "It won't take but two bictics," and actually be closer to the truth while still keeping a coherent, dozenal relationship to the surrounding units of time.