The Serpent Power by Sir John Woodroffe

Sir John George Woodroffe (1865–1936), also known by his pseudonym Arthur Avalon, was a British Orientalist whose work helped to unleash in the West a deep and wide interest in Hindu philosophy and Yogic practices.

This work is a description and explanation in fuller
detail of the Serpent Power (Kundali Shakti), and the
Yoga effected through it, a subject occupying a pre-eminent
place in the T a n t r a Shastra. It consists of a translation
of two Sanskrit works published some years ago in t h e
second volume of my series of Tantrik Texts, but hitherto
untranslated. The first, entitled " S h a t c h a k r a n i r u p a n a "
("Description of and Investigation into t h e Six Bodily
Centres"), has as its author the celebrated Tantrik P u r n a -
nanda Svami, a short note on whose life is given later. It
forms t h e sixth chapter of his extensive and unpublished
work on Tantrik Ritual entitled " S h r i t a t t v a c h i n t a m a n i " .