Commentary on the Essence of Battle

The rising of the vowel A original: Akara lasts for forty-eight days The text says "forty" (catvāriṃśad) in words but "48" in numerals in the Summer season Grishma, and for twenty-four days (24) in the Rainy season Varsha. [This completes the first period of 72 days].

The rising of the vowel I original: Ikara lasts for thirty-six days (36) in the Rainy season and for thirty-six days (36) in the Autumn season Sharad.

The rising of the vowel U original: Ukara lasts for twenty-four days (24) in the Autumn season and for forty-eight days (48) Again, the text writes "forty" but the numeral is 48 in the Winter season Hemanta.

The rising of the vowel E original: Ekara lasts for twelve days (12) in the Winter season and for the duration of the Cool season Shishira original: shishirayo for sixty days The OCR shows '6' but the mathematical cycle of 72 days per vowel requires '60' here; a horizontal stroke appears in the manuscript at this point.

The rising of the vowel O original: Okara [follows in sequence].

Such is the declaration of the Season Vowel ritu svara. Within these seasonal vowel periods, the "rising of the lunar mansion" nakshatra udaya occurs in eleventh-part divisions. This is measured as 6 ghatikas, 12 palas, and 43 vipalas A ghatika is 24 minutes; a pala is 24 seconds; a vipala is 0.4 seconds. By this precise measure, the risings of the eleventh-parts are determined.

Now follows the Solstice Vowel Ayanasvara:
There is the Southern Solstice Dakshinayana The period when the sun moves south of the equator, roughly July to December and the other is the Northern Solstice Somyayana Also called Uttarayana; the period when the sun moves north, roughly January to June. To be certain, the vowels A and E original: a-e are the vowels for these two paths. It is stated that in the Southern Solstice, the vowel A [presides].