Improvements in Perpetual Calendars.
Year: 1892

page_text: Date of Application, 22nd Dec., 1892-Accepted, 4th Feb., 1893
COMPLETE SPECIFICATION.
Improvements in Perpetual Calendars.
I, GEORGE DREYFUS, Engineer, of 32 Rue de Paradis, Paris, in the Republic
of France, 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 :--
This invention for improvements in perpetual calendars has for its object to
group together in a small space, tables of the year, the day of the month, the
month and the day of the week for a considerable period in such manner that the
name of the day of the week of any date whatever can be easily, rapidly, and
accurately obtained; or reciprocally the day of the month of which the year, the
month and the day of the week and the particular week of the month are
known.
A perpetual calendar according to this invention consists of a number card on
which are marked in seven year columns and seven month columns respectively the
numbers of the years for a desired period and the numbers 1 to 31 which are
always visible, and of a name card carrying, in divisions corresponding in size
respectively to the width of a year and a month column, the names of the months
and the names of the days of the week repeated in order several times and which
card is adapted to be moved relatively to the number card; the names and
numbers being arranged on the cards so that the name of any month can be
brought opposite any column containing the numbers of the years and be visible,
when the names of seven consecutive days will be opposite the month columns
and will be visible and correspond with the numbers in those columns for that
year.
In order to provide for leap years the number of the leap year is inserted in
two adjacent columns and January and February for leap years must be brought
opposite one column containing the number of the leap year and the other months
opposite the other column containing the same number; the numbers opposite
which January and February are to be brought being distinguished in any
suitable manner from the numbers opposite which the other months are to be
brought.
The accompanying sheets of illustrative drawings show various modifications of
a calendar constructed according to this invention.
Figure 1 is a face view of a calendar.
Figure 2 is a cross section of the same.
Figure 3 is a face view of the name card.
Figure 4 is a similar view to Figure 3 showing a modified arrangement of the
names of the days of the week and of the months.
The name card B is circular and is adapted to rotate behind the number card A
on a pivot o fixed in the number card and passing axially through the name card.
Portions of two annular rings are cut out from the number card, the axis of the
said rings being at the pivot o and the inner radius of one ring being equal to the
outer radius of the other ring so that portions of the name card B can be seen
through the openings cd so formed. The numbers 1 to 31 are arranged con-
secutively on the number card in five parallel rows in seven columns corresponding
to seven equal divisions of the week opening c and the numbers of the years are
arranged on the same card in parallel rows in seven columns corresponding to
seven equal divisions of the month opening d.
The name card B is formed with two annular rings e ƒ corresponding to the

page_text: C
e
openings in the number card and divided by equally spaced radial lines so that
seven divisions of either ring or fare equal in length to the corresponding
opening or d in the number card. In the ringe the name of a day of the week
is inserted in each division, the said names being placed in order and repeated
several times. In the ring the names of the months are inserted so that the name
of each month occupies one division and that the name of each month is in advance
of the name of the preceding month by as many divisions as the number of days
in the said preceding month is in excess of twenty eight, thus February and
March are on the same division and three divisions in advance of January, April
is three divisions in advance of March, and May is two divisions in advance of
April and so on.
The numbers and names are so arranged on the cards that if the name of any
month be brought opposite the column containing the number of a specified year,
then the name of each day of the week will be opposite a column containing the
numbers of the days of the month corresponding to that name. The numbers of
the leap years are repeated in an adjacent column as shown and January and
February of those years must be brought opposite the plain number and the other
months opposite the number marked with an asterisk.
In the modification shown in Figure 4 the names of those months which in non
leap years begin with the same day of the week are grouped together so that
they occupy only seven divisions and that the names of the days of the week do
not require to be repeated so often, being contained in nineteen divisions only.
In the modification shown in Figures 5, 6, and 7 the arrangement is similar to
that shown in Figure 4 except that the week opening and the month opening are
made as one opening c¹ and the names of the months, and days of the week are
brought close together on the name card B' which is in the form of a sector and
requires to have only a limited motion. In this case the sector can be revolved
round the pivot o¹ fixed in the number card A¹.
Figures 8, 9, 10 and 11 are similar views to Figures 1, 2, 3 and 4 respectively,
the name card B2 sliding vertically and across the number card A' and between the
two sets of seven horizontal columns containing the numbers to 31 and the numbers
of the years for the desired period. The week opening c² and month opening d²
are straight. The pieces P2 gummed or otherwise fixed to the number card A*
serve to keep the name card in position with respect to the number card.
Figures 12, 13, 14 and 15 are similar views to Figures 8, 9, 10 and 11 respectively
showing the name card B3 sliding horizontally across the face of the number
card A³ and between two sets of seven vertical columns containing the numbers 1
to 31 and the numbers of the years for the desired period. The name card passes
at S³ from the face of the number card to the back through slots in the number
card and at these parts the number card may be strengthened by the pieces P
gummed or cemented to it.
The manner of working the calendar is as follows:-For an ordinary year the
name of the month is brought opposite the column containing the number of the
year when the names of the days will correspond with the numbers 1 to 28, 1 to 29,
1 to 30, or 1 to 31, as the case may be. In leap years there are two adjacent
columns containing the number of the year and the months of January and
February are brought opposite one column and the remaining months are brought
opposite the adjacent column and the number of the leap year in this latter
column is provided with an asterisk, or is nnderlined, or one of the said numbers
is otherwise marked to distinguish it from the other, all the leap years being of
course distinguished in identically the same manner.
When desired to find the name of the day corresponding to a given date, the
name of the month is brought opposite the number of the year and the number of
the day of the month will be opposite the name of the day required. For example
the 15th May 1891 was a Friday, the 15th May 1896 will be a Friday, and the
16th January 1896 will be a Wednesday.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:
.
1. A perpetual calendar consisting of a number card on which are marked in
seven year columns and seven month columns respectively the numbers of the
years for a desired period and the numbers 1 to 31 which are always visible and of
a name card carrying in divisions corresponding in size respectively to the width
of a year and a month column, the names of the months and the names of the
days of the week repeated in order several times, and which card is adapted to be
moved relatively to the number card, the names and numbers being arranged on
the card substantially as described so that the name of any month can be brought
opposite any column containing the numbers of the years and be visible when the
names of the seven consecutive days will be opposite the month columns and will be
visible and correspond with the numbers in those columns for that year so that the
whole forms a calendar for the said period.
2. A perpetual calendar consisting of a number card on which are marked in
seven year columns and seven month columns respectively the numbers of the
years for a desired period and the numbers 1 to 31 which are always visible, and
of a name card carrying in seven divisions corresponding in size to the width of
a year column the names of the months, those months which in any non leap year
begin with the same day of the week being inserted in the same division and in
order according to the name of the first day of the month for that year and also
carrying in nineteen divisions corresponding in size to the width of the month
column the names of the days of the week repeated in order the cards being
adapted to be moved relatively to one another and the names and numbers being
arranged on the cards substantially as described, so that when the seven divisions
containing the names of the months are opposite the year columns and are visible,
the central seven divisions containing the names of the days are opposite the month
columns and are visible, and that the whole forms a perpetual calendar for the
Baid period.
3. A perpetual calendar, arranged and constructed substantially as described
with reference to the accompanying drawings.
Dated this 22nd day of December 1892.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.