Surya Siddhanta
तदन्तरालयोश् च्छाया याम्योदक् सम्भवत्य् अपि। मेरोर् अभिमुखम् याति परतः स्वविभागयोः॥
Between those limits, the shadow is cast both southward and northward ; beyond them, it falls toward the Meru of either hemisphere respectively.
english translation