Odd calendar

[bagerap]

I'm very fond of a calendar medal, they're often a good reflection of society when they were issued.
This one though has me puzzled.
What is a Day Table, and why does it have 37 days?

[THCoins]

You have to add the number behind the month to the date. The number you then get you look up in the day table to get the day of the week.
So 1-1-1899 = 1 + 0 = 1 is a sunday.   31-07-1899 = 31+6 = 37 is a Monday.

[bagerap]

Thank you. This is little short of genius. And yet in 15 years of collecting calendar medals, this is the first of its kind that I've seen.

[THCoins]

Not really, the principle is quite simple. The number behind the month gives the offset in weekdays at which the first day of the month falls. As it starts on Sunday 1-1-1899 its offset is 0. As Januari has 31 days the offset of the first day of Februari is 3 (31-28). And as Februari has 28 days, exactly 4 full weeks, the ofset for March remains the same.
To get the weekday you just do (Offset + Date) modulo 7.

Elementary, my dear Watson 

[Figleaf]

Genius extended. By adding a year table, you can cover, say, 200 years. In fact, the year table contains some duplication, so it would fit on the page. Leap years are the principal problem. You will find that the monthly numbers for 1899 are the same as on the medal. There is probably a computer routine to do this now, as I have two electronic devices that want to know what year it is and display the day of the week.

Another fun novelty to amaze Amanda before asking her father for permission to marry her. As you said: "a good reflection of society when they were issued".

Peter

[malj1]

 "Leap years are the principal problem"

...and the problem would start with 1900 not being a leap year.

I notice the name O'Sullivan's - presumably an Irishman.

[malj1]

By quite a coincidence I received an email today with a query on another Calendar medal / watch fob. I can see its a calendar for the 1880 - 90's and I think it appears to be in German. The centre has a name that I can't quite make out and PATENT.

"Can anybody help me by identifying what this medal/tool is, how does it work, and is it worth anything.

Regards
Doug Joubert"

[THCoins]

First you set the year under one of the seven holes corresponding with the month you are intersted in.
Then you look at the other side to see at which day of the week a date in this month falls.

Principle is the same as the initial medal and Figleaf's table:

Turning the dial sets the offsetday of the weekday calculation. The months are ordered based on the offset day. The 7 holes correspond to the 7 possible offset days. So two months above the same hole share the same offset day. January and february are taken with the previous year to make the arrangement easier.
The years are arranged corresponding to the shift of offsetdays over the consequtive years.
If 1-1-1890 falls on a wednesday  than 1-1-1891 falls on a thursday. So 1891 would be placed under the hole one position anti-clockwise from 1890 to reflect the shift in offset day. 1-1-1892 is on a Friday. But 1892 is a leapyear. So 1-1-1893 is on a Sunday, a shift of two offset days. Thus, because January and February are taken with the previous year, 1892 is placed two holes anti-clockwise from 1891.

Principle is simple, explaining in short more difficult.

[FosseWay]

Back in the mists of time I was a choirboy in church. It was marginally more interesting to read all the introductory information in the prayer book than it was to listen to the vicar's interminable sermons. I remember pages and pages of tables such as the one Peter showed upthread, except in 17th century English, plus additional information, on how to calculate the date of Easter and work out the dates of Sundays from 1662 until God knows when (well into the 22nd century IIRC). I was mystified by Golden Letters but grasped the Gregorian Calendar's treatment of leap years fairly easily.

I still remember a lot more about how the calendar works than whatever the vicar was rabbiting on about... 

[constanius]

Back in the mists of time I was a choirboy in church. It was marginally more interesting to read all the introductory information in the prayer . I was mystified by Golden Letters but grasped the Gregorian Calendar's treatment of leap years fairly easily.

This 1766 calendar medal(not listed in Ackerman) has the Golden Number 19.  Dominical Letter E.  Sun Cycle 11.  Epact 18.



Pat

[Henk]

I recently got an example of the 1899 o'sullivan's calender medal illustrated above. When looking for information about it, I found this page. The explanation of THCoins is very useful. I acquired the medal at the right moment as in the present year, 2023, all days fall at the same dates as in 1899. So  I can actually use it!

[brandm24]

I recently came across this interesting calendar token issued by the Tuckinghill Foundry Co. in Cornwall in 1907. Though a bit hard to see because of a poor image and many dings on it it's a 20 year calendar.

There appears to be a center hub which begs the question. Is there a missing spinner or something similar to what Mal's post (#6) shows on his example? Though well explained by several posters upthread, the usage of these calendars is still difficult for those of modest capacity...like me.

Bruce   

[THCoins]

It looks complete to me. The instruction for use is clear near the left margin in your lower photo. So the top plate in the lower picture should be able to rotate over the bottom part.

[brandm24]

I see it now. Thanks.

Bruce