सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

that day go on counting the number of days, which will
be 365 when the Sun again rises very nearly at the same
point and just to the south of the east point. It will be
found that the Sun will rise the next day just a little to
the north of the east point, which means that the Sun has
taken 365 days and a fractional part of a day to complete
his revolution round the stars. Having noted the two
points of intersection of the gnomonic shadow with the
circle, on those two consecutive days when the Sun
happens to rise just a little to the south and then on the
next day just a little north of the east point, and having
measured the arcs in minutes between those points of
intersection and the western point of the horizontal circle
(western because the gnomonic shadow of the rising Sun
is cast towards west) then the following rule of three is
to be applied. If during 60 ghatis of the day, the sum of
the arcs in minutes is covered, what will be the time
taken by the shadow to traverse the arc between the west
point and the northern point of intersection. This added
to 365, gives the number of civil days in an year. Here
it will be noted that this year is tropical because rising in
the east signifies the Sun's position at an equinox.
Verse 8. The number of solar days in a kalpa is
equal to 1555200000000 and of the lunar days or tithis is
1602999000000.
Comm. The solar days here cited are counted at the
rate of 360 per year; and the lunar days at the rate of 30
per lunation. Tithi is defined as mentioned by us under
verse 31 of the previous section. Since there are thirty
tithis in a lunation, their enumeration is quite alright;
but there seems to be a little oddity in saying that there
are 360 solar days in an year. This kind of a solar day
is a little longer than a civil day and does not correspond
to any particular motion of the Sun, say for example the
time taken by the Sun to move a degree along the ecliptic.
The definition of solar days pertains only to a stipulation