THERE IS an old English saying that goes:
New Year's Day is but an inch wide
But Twelfth Night boasts a cock's stride;
or as our Irish ancestors put it in their own inimitable idiom:
Fad coisceim coiligh La Coille,
Beiriu spola La Nollag Beag.
There seems to be confusion as to whether a cock's stride in metaphor is long or short; although anyone who has seen the purposeful gait of a farm yard cockerel on business bent might well presume the former.
Either way, the message in, both sayings is the same: the days grow longer during January, and at a seemingly accelerating pace.
Now one might think that this brightening should begin a little earlier, specifically, at the winter solstice around December 21st, since that is undeniably the shortest day of the entire year.
But the process is not quite so simple: it depends on whether you measure the cock's stride in the morning or, at nightfall. The eccentricity of the Earth's orbiting arrangements combined with averaging techniques incorporated into the way we set our clocks combine to import a certain lack of symmetry to the waxing of the daylight hours.
The result is that although the interval between sunrise and sunset is indeed at a minimum around the solstice, the latest sunrise and the earliest sunset do not occur simultaneously that same day.
The earliest sunset of the year occurs, in fact, around December 13th, so the evenings have been getting brighter for nearly two months now, albeit imperceptibly ate first. The latest sunrise, on the other hand, does not take place until the very end of December, so it is only with the arrival of January that a later, dawn occurs.
During the last week or two, however, the lengthening of the day at both ends has become much more noticeable.
In the case of sunrise, for example, the change in the early days of January is very gradual: dawn at the middle of that month is only a few minutes earlier than a week or two previously. As time goes by, however, the variation from week to week increases, until by mid February the time of sunrise moves earlier by about 17 minutes every week.
This rate of change reaches a maximum of about 19 minutes per week at the vernal equinox, and then eases and becomes very gentle again as we approach the summer solstice late in June. In the same way, the rate at which the evenings become longer is increasing at present, and will continue to do so until about, March 21st.