Working program and operating steps.

 In our work in the various classes we have summarizzed the fundamental steps in the history of the calendar and the distinction between real solar time and average solar time but we must underline that we found that this notions are not the most stimulating approach, or the most valuable methodologically in stimulating the interest of the students on the problem of measuring time.

We have used these notions in order to make the students understand, by means of historical observations and references,  the history of the time equation and the various choice as linked to local and biological factors. 

On this point it is possible to conduct experiments in the classes (to evaluate the time without the help of a watch in conducting various activities, to compare it with the evaluation of people of different ages, to give special readings.....) 

As for the calculations of dates we briefly refer to the Roman system that used three fixed days for the date of the month:   the first (Calendae) the 5th or 7th (Nonae) and the 13th or 15th (Ides).

As for the hours the Romans used the first Italian scale we know in historical time.

It is known as the scale of the horae temporariae.

>>They distinguished the "dies naturalis" (from the dawn to the sun set) from the "dies civilis o legitimus" inclusive of dies naturalis and the "nox".

They divided both, the day and the night,in the four parts of three hours each.

The four parts of the day were closed by hours "tertia",   "sexta", "nona" and "duodecima" which coincided with sun set (solis occasus). 

At equinozi theese hours coincided with ours 9, 12, 15 and 18.

The lenght of day in Italy varies from a minimum of about 8 hours to a maximum of about 16 hours, around the summer solstizio. 

So in a period of solstizio the temporary hours may last 20 minutes less or more than ordinary hours.

In order to know the hour of a day ,it was built a sundial calibrated on latitude of Rome, in 56 B.C. and an horizontal "meridiana" in Campo Marzio.

In the proceding they built also clessidra and idraulic and mecanic clocks which were scanning a time fluing in a uniform way in order to count, for example, the time to dedicate to each orator. So it means hours " aequalia" or equinoziali. 

The device you can see in the picture was built by students of second year of Istituto Professionale (16 years old ).

After the fall of Impero Romano d’ Occidente it has been introduced in Italy an important novelty imported from Jewish.

They began to count the start point of a day from the sunset.  

The knowledge of the time of a day became a knowledge of all the people only beginning from IV cent., when ,because of freedom in religion, after Costantino, the sound of bells used to remaind time for prayers but also indicate all over the countryside the hours for men coming back from working.

So, temporary hours like those one in use in roman life but with the beginning point in the sunset, gave us during all medieval time news like this one:

" an earthquake in Pontremoli at two o’clock in the night....." that means 45 past 8 p.m.

 After temporary hours, we had what was called " ORE ITALIANE ".

It was an hour-counting system in use all over great part of Europe, from 1200 to 1800.

Their characteristic was to be all the same lenght but, as the starting point was the Ave Maria prayer in the evening, at the end of twilight, meaning about half an hour after sunset, we know that it means that different places with different distance from equator had different start point.

The device built by the students, that you can see in the picture,   helps them to consider that it is an hour-counting system varying with seasons and with latitude, although they are hours of the same length. 

We have in Italy in used to say " portare il cappello sulle ventitrč "; it is " to wear the cap on the twentythree".

The reason of this use becomes from italian hours and it is still in use. It dependes by the fact that one hour before the sun set ( it is twentythree in this way of counting hours) you have to put your cap in a way so that sun rays do not hit your eyes.

     Students showed to appreciate this curiosity !

Referring to the same way to count hours we can find that Dante Alighieri says that the death of Beatrice happens " alla prima ora del nono giorno del mese " that means "at the first hour of the ninth day of the month " of June and it corresponds to 8 June, one hour after the sunset.  

We have, of course, many other examples about.

In order to put into practice the topic, after a discussion in the classroom, it were proposed exercises.