The
Book belonging to Lambspring Monastery
Of the Order of Saint Benedict
Of the English monastic community. 
The
method of calculating the nones or ides after the kalends of the twelve
months. and also how many days they consist of…,,, 
January.
August and Dece
mber· have 4.nones
·19 kalends
after ides. and 31.
days. 
March. May
July and October
have 6. nones.
17. Kalends after ides
and 31 days. 
April·
Ju
ne. September and
November· have·
4 nones.
18. kalends after
ides. and 30
days. 
But February
has. 4. nones
16. kalends after
ides. and 28
.days 
and in a leap
year
has 29 days
and a moon
of 30. 
But all
months
have an octave
of ides. 
THE
RULES FOR CALCULATING THE FERIAL and the concurrent number. THE
RULES FOR CALCULATING LUNATIONS and EPACTS. 
March 
V 
B 
i.ii.iii.iii. 
September 
V 
D 
Zero 


April

I 
B 
vi.vii.i.ii 
October 
V 
G 
xi 
F 
xii 
May

III 
B 
iiii.v.vi.vii. 
November 
VI 
E 
xx.ii 
D 
xxiii 
June

VI 
B 
ii.iii.iiii.v.

December 
VII

A 
iii

G

iiii 
July

I 
B 
vii.i.ii.iii. 
January 
IX 
D 
xiiii 
C 
xv 
August

IIII

B 
v.vi.vii.i.

February 
X 
B 
xx.v

A 
xxvi 
September

VII 
B 
iii.
iiii.v.vi. 
March 
IX 
E 
vi 
D 
vii 
October

II



April

X 
C 
xvii 
B 
xviii 
November

V 


May 
XI 
F 
xxviiii 


December

VII 


June 
XII

B 
ix 


January

III 


July 
XIII 
G 
xx 


February

VI



August 
XIIII 
C 
i 



Add
together the regularis of each month and the concurrents of any year.
If 7 is the result, [day 7] is the ferial day which falls on kalends.
If it is more than 7, take away 7 and the remainder is the ferial
day that falls upon the KALENDS. 
Add
together the regularis of each month and the epacts of any year. If
30 or less is the number, that is the age of the moon which falls
upon the kalends. If the number is more than 30, take away 30 and
that which remains is the age of the moon that falls upon the KALENDS 