The Seattle Post Intelligencer

WHAT'S THE TIME?
Clocks and the Sun Do Not Always Agree in Marking the Hour.

Leisure Hour

There are few questions more frequently put than "What time is it?" "Can you tell me the true time?" A stickler for exactitude might reply: "What kind of time do you mean? Apparent time or mean time? Real time or standard time? There are all these kinds of time, not to speak of others. It is only within the last two generations, within, indeed, the reign of our sovereign, Queen Victoria, that the subject of the difference of most of these kinds of time has become of pressing importance to any but theorists.

In one of the public gardens of Paris a little cannon is set up with a burning glass attached to it in such a manner that the sun itself fires the cannon as it reaches the meridian. This of course, is the time of Paris noon—apparent noon; but it would be exceedingly imprudent of any traveler through Paris who wished say, to catch the 1 o'clock express to set his watch by the gun. For if it happened to be in February he would find when he reached the railway station that the station clock was faster than the gun by nearly a full quarter of an hour, and that his train had gone, while toward the end of October or the beginning of November he would find himself as much too soon.

Until machines for accurately measuring time were invented, apparent time—time, that is to say, given by the sun itself, as by a sun dial—was the only time about which men knew or cared. But when reasonably good clocks and watches were made it was very soon seen that at different times in the year there was a marked difference between the sun dial time and that shown by the clock—the reason being simply that the apparent rate of motion of the sun across the sky was not always quite the same, while the movement of the clock was, of course, as regular as it could be made.