सुरुङ्गायुक्ते वा कूपे नागमनियतशिरस्कं हिरण्योपहारेण दर्शयेत् ॥ कZ_०५.२.४२ ॥
suruṅgāyukte vā kūpe nāgam aniyataśiraskaṃ hiraṇyopahāreṇa darśayet ।
Or, in a well fitted with a tunnel, he should display a “nāga” whose head appears unpredictably, in connection with the offering of gold.
A tunnel-linked well allows an agent/animal/effigy to appear and disappear, simulating a nāga’s unpredictable emergence.
The appearance is conditioned on ‘hiraṇya-upahāra’—the act of offering gold.