Improvements in Calendars and Date Calculators.
Year: 1898

page_text: Date of Application, 14th May, 1898-Accepted, 9th July, 1898
COMPLETE SPECIFICATION.
Improvements in Calendars and Date Calculators.
I, CHRISTOPHER HENRY ELSDON, Manager, of 36, Northbrook Road, Ilford, in
the County of Essex, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
The object of the present invention is to provide a calendar from which can be
ascertained the days of the week in any given month, in any particular year.
The calendar may be constructed to cover a period of any number of centuries
within which readings of days and months may be obtained, but in explaining
my invention I have selected figures to include from the year 1701 to the year 2999,
so as to fully illustrate the nature of my calendar.
According to my invention, the calendar consists, in its most convenient form,
of three discs of different sizes, furnished with a common centre, upon which they
are individually capable of turning. These discs carry the figures and symbols to
indicate days, months, and years, as hereinafter described:
In the drawing,
Fig. 1 is a face view of the calendar.
Figs. 2 and 3 are respectively front and back views of the largest or back
disc, No. 1.
Figs. 4 and 5 are similar views of the middle disc, No. 2.
Fig. 6 is a transverse section on the line X-X, Fig. 1.
The discs, which I call 1, 2, and 3, respectively, 1 being the back, 2 the middle,
and 3 the front disc, may be of any suitable material, such as cardboard or sheet
metal, and may be recessed and fitted into one another, as shewn in Fig. 6, or they
may be flat. The disc 3 need not necessarily be a complete disc, but for con-
venience of description I have elected to show it and describe it as such herein.
The disc 1 has in it radial slots or their equivalent, seven of which are in this
case shown, although five only are required for use in the period 1701-2999 before
mentioned. Upon the face of the disc 1, near the circumference, so as to shew
outside the disc 2, are represented the months of the year, with the number of
their days, and on the back, above the slots, are arranged colunins of figures
representing the centuries. The months January and February, it will be noticed,
are represented twice, the positions indicated by dotting being for use in leap
All the months are by preference arranged around the disc in their proper
order from January to December, but at various intervals, which intervals are
determined as hereinafter explained. The disc 2 has arranged, in order around
its circumference, the initial letters of the days of the week, which shew beyond
the circumference of the disc 3.
years.
The days of the week are repeated five times, giving a total of thirty-five
divisions. This repetition of the days of the week permits of the arrangement of
the months, as on disc 1 (see Fig. 1), so that if the day of the week is known, say,
of January 1st in any particular year, and the disc set accordingly, as in Fig. 1,
the name of the first day of all the other months will be found opposite the name

page_text: of each of the said months. For instance, January 1st is perhaps on Friday;
December 1st is on Wednesday; June 1st on Tuesday; and so on, throughout
the year.
The arrangement of the months at various intervals, to give this result, is arrived
at by means of the disc 3, which has on its face the days of the month set in seven
vertical columns (see Fig. 1) in the following manner;--
January is first placed arbitrarily; the disc 2 is then turned until the day of
the week, in any selected year, is made to accord with January 1st. If the
year 1802 be selected, for example, and January having been found to begin on
Friday, the disc 3 is turned to bring the figure 1 opposite January. By reading
down the figures against the days of the week in their proper sequence, it will
be found that January, having 31 days, ends on Sunday. Monday, therefore,
is the first of February, and the month is placed accordingly on disc 1, adjacent
to the initial letter of that day next following the Friday on the disc 2, as then
Bet.
The disc 3 is now turned so as to bring the figure 1 opposite February, and the
28 days are read down, shewing the month to terminate on Sunday. March,
therefore, begins on Monday, and it is therefore placed opposite that letter next
following the commencement of the previous month, and so on throughout the
circle.
It will thus be seen that where the day of the week of a date in any particular
year is known, and the discs 1 and 2 are set accordingly, the names of all the other
days in that year can be readily ascertained by means of the disc 3. I will now,
however, explain how to set the discs 1 and 2 to the year desired.
It has been pointed out that the back of disc 1 is marked with figures indicating
centuries opposite the slots (see Fig. 3). These figures, for the most part, give
the first year of the century, as 1800, 1900, 2000, &c., which I will deal with
first.
These century figures are supplemented by figures carried on the back of disc 2,
which show through the slots in disc 1, and are changed by rotating the discs one
on the other.
The supplementary figures are arranged in rings in a reverse direction, the
first ring beginning 00, 01, 02, &c., to 27. The second ring begins with 28,
beneath the 00 of the previous ring, and follows with 29 under 01, and so on the
figures are arranged until 99 is reached (see Fig. 5).
There are thus 28 radial columns of figures arranged in blocks of 4 columns each,
the blocks being divided by seven spaces, making in all 35 radial divisions,
corresponding with the radial divisions on the other side of the disc (see Fig. 4).
A day of the week, as indicated on the disc front, is placed opposite a column of
figures to be found on the back, and in arranging these, in the first instance, it
is necessary to ascertain what day of the week is correct with regard to the com-
mencement of a particular year. After once fixing this, there is no further
difficulty, as the same day recurs every 28 years. Take, for example, January 1st
1802, which happens to be Friday, as before mentioned, the 02 should be so placed
at the back of the disc 2 as to be opposite the initial letter F of Friday on the
other side; 03 will likewise correspond with Saturday, and so on, in regular
sequence, one day of the week being missed where there is no corresponding
number at the seven blank spaces between the figure columns at the back of
disc 2.
Referring to the special figures on the back of disc 1 in 1752, the calendar was
re-arranged and eleven days, September 3rd to 13th, were excised from that year.
It has therefore been found necessary to particularize that year in the present
arrangement, and also those following, to the end of the year 1799, instead of
adhering to the plan of naming only the first year of the century on the disc 1
and leaving the intermediate years to be filled up with the aid of the figures on
the disc 2.

page_text: The leap years are marked in the calendar in dotted figures, which should be
read in connection with the dotted positions of the months January and February
on disc 1 (see Figs. 1 and 2).
To ascertain any particular day of the week by the aid of my invention, it will be
necessary to proceed as follows:-Turn to the back of the discs, and set Nos. 1
and 2 to the required year; then, regarding the front, set the figure 1 on disc 3
to the month desired. The initial letters of the days of the week, as they are
on the front of the disc 2, adjacent to the figures on disc 3, will then correspond
with the days of the month, as represented by those figures. The reader can then
read off the name of any day he requires to know.
It will be a convenience to provide means for fixing the discs 1 and 2, and pre-
venting their rotation, when set for inspection. This may be effected by a sliding
catch A, or any other convenient device.
I may remark that a calendar on similar lines, to give the same results, may be
constructed with fewer repetitions of the days of the week, but in that case
something of clearness would be sacrificed, and the calendar would not be so easy
to read. For example, the months, instead of being placed, as shewn, in sequence,
would have to be, in some cases, placed one over the other, where the days of the
week of two or more months would be the same.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
In a calendar for indicating the day of the week in a particular month of a
particular year, the combination of three discs, or their equivalent, movable on
one another, and carrying thereon figures and symbols, which figures and symbols,
being set by moving the discs in the manner above described, will give the reading
desired, substantially as set forth.