Do you have the time please? It depends on your time system.
CHAZAL AND TIME
How did people tell the time? Although the ancients had water clocks, candle clocks, and even primitive mechanical clocks, the Tanach and Chazal seemed to rely almost exclusively on observing the sun.
For example, when Yeshayahu informed King Chizkiyahu that he would survive a fatal illness and live another fifteen years, Yeshayahu concluded: “And this is the sign from Hashem for you that Hashem will do this thing that He spoke. Behold, I will turn back the shade of the steps that descended the steps of Achaz in the sun back ten steps, and the shade will go back ten steps on the steps that it descended” (Yeshayahu 38:7, 8).
Rashi explains that the steps of Achaz were “sort of steps made opposite the sun to detect the hours of day with them, like a horologion (a timepiece) that craftsmen make.”
However, the Gemara generally ignores sundials and relies on detecting the time directly from the sun; for example, various sugyos discuss people determining the time from the sun’s height.
One of the rare places where Chazal mention another way of detecting the time is where the Zohar (Bereishis 92b) describes a water clock:
“R. Abba traveled with his son R. Yaakov from Trunia to Teveria to visit his father-in-law, and on the way they spent the night in the village Tarsha. Before going to sleep, R. Abba asked the baal bayis, ‘Do you have a chicken?’ “’What for?’ asked the baal bayis. “’I wish to wake up at midnight,’ replied R. Abba, ‘and I need a chicken to waken me.’ “’There is no need,’ said the baal bayis. ‘Next to my bed is a scale. On one of its pans I place a weight and on the other I put a container of water with a hole. By midnight the container empties and the opposing weight falls to the fl oor making a noise in the whole house.’”
Why do we split the day into 24 hours in the first place? Why not 20 or 26 hours? After all, an Egyptian sundial from about 3,500 years ago split daylight into ten hours instead of twelve.
Strangely, the Tanach does not mention the concept of 24 hours at all, and it appears for the first time in the Gemara and Medrash. For example, the Gemara (Sandhedrin 38b) states that, “The day has twelve hours.”
The Chazon Ish (Yoreh Dei’ah 85:74) initially writes that hours are not a mere human convention but the intent of the Torah in order to perform certain mitzvos. For example, beis din need to ask witnesses what hour of the day they saw something happen. Then he concludes, “And all this requires investigation and we cannot reach a conclusion about it.”
On the other hand, the Urim veTumim (30:13), the Ohr Sameach (Eidus 1:4) and the Chazon Ish elsewhere (Orach Chayim 13, letter 1) write that dividing the day into twelve hours is a human convention and not something decreed by the Torah or by Chazal.
WHAT IS AN HOUR?
Although the Gemara does not say so explicitly, most poskim hold that the hours that determine mitzvos like Kerias Shema fluctuate according to the length of the day. Thus, an hour is one twelth of the day and the longer the day the longer its hours, so that we read Kerias Shema later in midsummer than in midwinter.
Rambam is one of the earliest Rishonim to mention this vital point (Peirush haMishnayos Berachos 1:2). A minority of Rishonim and Acharonim hold that Chazal’s hours are the same as the unvarying hours we use today, and have the same length the whole year. According to this opinion, the last time to say Krias Shema is 9:00 a.m. the whole year round. Although Rav Eliezer of Munkach rules like this opinion lekula in his Minchas Eliezer, most poskim disagree and the Igros Moshe rules that one does not have to be concerned about it even lechumra.
A strange system widespread throughout the Ottoman Empire and still used in Yerushalayim today, was “Moslem time” where people set their clocks at 12 every sunset. Because days are usually shorter or longer than their preceding day, people had to reset their clocks at sunset every day. With this system, by midnight it was only six o clock.
A convenient feature of the Moslem clock was that every sunset muezzins (people who call Moslems to prayer) yelled out from every minaret in town so people didn’t even have to look out for the sun to know the time.
As one rav wrote: “(Immediately) after sunset, the Arabs on duty shout and scream so that their voice is heard in the whole town at 12-o-clock, and so it is every day. In the Diaspora people do not understand this… But, the truth is that the national custom here, instituted by the king and his ministers, is to be careful to begin night on clocks everywhere at the same time, to begin the count in the evening as above – the first hour… And if the day alters a few minutes, whether longer or shorter, people set their timepieces later or earlier… and synchronize it with the shouting at the 12th hour.”
In its heyday, Moslem time was popular all the way from Greece to Morocco, but after the British conquered Palestine it gradually dwindled until today when it is only used by some Arabs and by some Yerushalayim Jews who prefer it because it starts at sunset in accordance with the verse, “And it was evening and it was morning.”
Some rabbonim, including Rav Shlomo Alfandri (chief rabbi of Damascus and Istanbul who spent the end of his life in Eretz Yisroel) went as far as to say that the modern time system that contradicts our heritage by starting the day at midnight is a conjunct of idolatry.
The catch with Moslem time was that many poskim held that halachic sunset was a few minutes earlier, probably because they held that halachic sunset is determined by its visual sighting, while the Moslems went according to the earlier sunset at sea level.
Thus Rav Yehuda of Ayash writes, “My teacher said that when their caller cries out close to dark… it is already half way through dusk.”
THE SUN OR THE RAILWAY
In the past, every town reckoned its time according to local noon and it bothered no one. Who cared what was going on over the next hill!
Things remained unchanged even after the invention of reliable clocks. For centuries, people happily reset their unreliable clocks by the midday sun. Then, in the 1840s, England constructed a network of telegraphs that united the country, providing instantaneous communication on an ongoing basis. For the first time, people began realizing that everything was out of sync. To make things worse, entrepreneurs were developing nationwide railroads and people would not be happy if a train from a distant town chugged in ten minutes late.
In 5607/1847 the Liverpool and Manchester Railway created their own standard time for the whole of England, and within eight years it was being used by 98% of English public clocks. Railway men began pressing parliament to formalize this arrangement by law, but, like most innovations, this one too ran into resistance. As one newspaper declared: “Rally around Old Time with the determination to agitate, and if needs be, to resist this arbitrary aggression. Let our rallying cry be: ‘The Sun or the Railway!”
In 5611/1851, Sir George Biddel Airy, the British Astronomer Royal (chief astronomer) established Greenwich as the Prime Meridian – the official center of the world where east meets west.
According to this arrangement, every spot in the world would be measured east or west of an imaginary line running from the north to south pole through Greenwich near London. 180 degrees away at the other side of the world would be the international date line.
As Greenwich is a big place, Airy plonked his Meridian line on the crosshairs of a telescope he had built a year earlier. If you want to straddle two hemispheres at once, go to Greenwich and stand over its Meridian line that splits east from west.
Greenwich time took over. For a while, some clocks had two minute hands, one to mark local time and a second one for Greenwich time, but by 5640/1880 it became legal time throughout England. Four years later the Greenwich Meridian line was internationally formalized when U.S. President Chester A. Arthur organized the International Meridian Conference in Washington D.C. attended by 41 delegates from 25 nations.
The chief conclusions were 1) “That it is the opinion of this Congress that it is desirable to adopt a single prime meridian for all nations, in place of the multiplicity of initial meridians which now exist. 2) That the Conference proposes… adoption of the meridian passing through the centre of the transit instrument (telescope) at the Observatory of Greenwich as the initial meridian for longitude.”
However, the Greenwich Meridian was chiefly for use at sea. The resolution specifically stated that it “shall not interfere with the use of local or standard time where desirable.”
For England, that only has one time zone, this was not a problem, but what about the USA that stretches through a number of time zones? How did Americans keep their trains running on time? For a while, USA railroad companies ran on their own times and some stations kept several clocks running to show them all. The problem was resolved on the “Day of Two Noons” in 5643/1883, when railroads reset their clocks to four standard time zones at noon, and most of the USA soon followed suit.
Since the 1920s, the whole world has been using time zones based on splitting the world into 24 segments of 15 degrees each, each one an hour apart from the next.
Now at last, when someone asks you the time you can give an accurate, unambiguous reply.