The above symbol - minus the point - is a sign for Vishnu. Turned horizontal it is a sign for Shiva.
Esoteric Masons, knowing that the chakra above the crown, in the Kabbalah, is called The Point within the Circle, have combined the Vishnu sign with the Kabbalistic symbolism. Thus a Mason acting from that chakra cannot err.
Hindu symbolism entered Masonry after the British arrived in India. For example the Veils that appear in some forms of the Holy Royal Arch, are the planes of existence of the Hindus.
The adoption of such esoteric teachings indicates that Masonry, pre-1717, contained advanced initiates.