This book, drawn on his own experience and older, now probably lost works, was written in the 1500's by an Indian Yogi named Svatmarama. This is an English translation from the Sanskrit by Brian Akers, and published by YogaVidya.com, at whose website you will find a downloadable PDF copy, of course it's not the whole book. You can also buy at book stores, (I think I bought mine at Barnes and Noble), or at Amazon.com. For it's size, it's not cheap at around 25. US, but for the knowlege alone it's worth many times that, if you use the techniques to regain, or improve your health, it's priceless.
After mastering asanas the yogi possessing self control and eating a suitable moderate diet should practice pranayama as taught by his Guru.
When the breath is unsteady, the mind is unsteady. When the breath is steady, and the yogi becomes steady. Therefore one should restrain the breath.
As long as there is breath in the body, there is life. Death is the departure of breath. Therefore one should restrain the breath.
When the nadis are dirupted by impurities, the breath doesn't enter the middle (the Sushumna). How can umani exist? How can the goal be attained?
The yogi is fit to control the prana only when all the nadis disrupted by impurities become pure.
Therefore always do pranayama with a sattvik mind so that impurities in the Sushumna nadi attain purity.
The yogi having assumed Padmasana should inhale prana with the moon (the left nostril or Ida), After holding as long as possible, he should exhale with the sun, (the right nostril or Pingala).
He should fill the interior slowly by inhaling prana with the sun. After holding in the prescribed manner, he should exhale with the moon.
He should inhale through the one with which he exhaled, hold with effort, then exhale slowly and without force through the other.
If prana is inhaled through the Ida and retained, it should be exhaled through the other. If the breath is inhaled through the Pingala and retained, it should be exhaled through the left. The nadis of yogi's who regularly practice in this manner of sun and moon become pure after three months.
Gradually increase the kumbhakas to eighty four times a day - morning, midday, evening, and midnight.
In the beginning there will be sweat, in the middle there will be trembling. In the end one obtains the goal. Therefore one should restrain the breath.
Rub the body with water born of fatigue to make it firm and light.
Food containing milk and ghee is recommended for the initial phase of practice. The adoption of such a rule is unnecessary after one's practice is established.
Just as the lion, elephant, or tiger is tamed step by step, so the breath is controlled. Otherwise it kills the practitioner.
Correct pranayama will weaken all diseases. Improper practice of Yoga will strengthen all diseases.
Irritation of the breath causes hiccups, asthma, coughing, headaches, earaches, pain in the eyes, and various diseases.
Exhale the breath very properly. Inhale it very properly. Retain it very properly. Thus one obtains success.
External signs appear when the nadis are pure. The body will definitely be lean and bright.
Retention of the breath as desired, stimulationof the digestion, manifestation of the nada, and good health come from purifying the nadis.
One having too much fat and phlegm should first do the six karmans. But one who doesn't need, not do them since his humors are equable.
These are the six karmans: Dhauti, Vasti, Neti, Trataka, Nauli, and Kapalabhati.
These six karmans - purifying the body, producing remarkable qualities - are to be given only to the worthy. They are honored by the best yogi's
Slowly swallow a wet cloth which is four fingers wide and fifteen hands long in the manner instructed by one's Guru. Draw it out again. This is called Dhautikarman.
Coughing, asthma, enlargement of the spleen, leprosy, and twenty other phlegm diseases vanish because of the power of Dhautikarman. In this there is no doubt.
Assume Utkatasana in water as deep as the navel. Insert a tube into the anus. Contract the anus. This cleansing is Vastikarman.
Enlargements of the glands, spleen, and abdomen - and all diseases arising from wind, bile, and phlegm - perish due to the power of Vastikarman.
Vastikarman in the water, when regularly practiced gives clarity to the body constituents, the senses, and the mind. It gives luster to the body, stimulates the gastric fire, and eliminates all defects.
Insert a very smooth thread nine inches long into a nasal passage and withdraw it from the mouth. This is called Neti by the masters.
Purifier of the skull and giver of divine sight, Neti quickly destroys the flood of diseases originating above the collarbone.
Gaze with motionless eyes and concentration at a minute point until tears flow. This is called Trataka by gurus.
Trataka removes eye diseases. It is a closed door to lethargy and so on. Strive to keep it secret - as if it were a gold box.
Lower the shoulders. Revolve the stomach left and right with the speed of a strong whirlpool. This is called Nauli by the masters.
This Nauli is the crown of Hatha practices. It kindles a weak gastric fire, restores the digestion, etc., always brings happiness, and dries up all defects and diseases.
With fat, phlegm, diseases, impurities, etc., removed by the six karmans, one should do pranayama. One will succeed without strain.
"All impurities dry up by pranayama alone." Speaking thusly the other karmans are not approved of by some teachers.
Those who have the nadis under control from gradual practice raise the apana wind in the esophogus and vomit the stomach's contents. This is called Gajakarani by knowers of Hatha.
Even Brama and other gods engaged in pranayama because they feared death. Therefore one should practice pranayama.
As long as the breath is retained in the body, as long as the mind is calm, and as long as the sight is in the middle of the brows, where is the fear of death?
The breath splits open the mouth of the Sushumna and enters easily once all the nadis are purified by restraining prana correctly.
Steadiness of mind is born when the breath moves in the middle. This state of mental steadiness is manonmani.
Those knowing the procedures do various kumbhakas to achieve it. From the practice of various kumbhakas, one obtains various powers.
These are the eight kumbhakas: Suryabhedana, Ujjayi, Sitkari, Shitali, Bhastrika, Bhramari, Murccha, and Plavini.
A bandha named Jalandhara is to be done at the end of inhalation. Uddiiyana is to be done at the end of kumbhaka and the beginning of exhalation.
The prana will enter the Brahma nadi when contraction of the throat, contraction beneath, and retraction in the middle are done.
Having raised the apana upwards, the yogi should guide the prana below the throat. Being liberated from old age, he will be a youth of sixteen.
Form an asana on a comforable seat. Slowly draw in outside air, through the right nadi.
Form the kumbhaka to the limit - from the hair to the toenails. Exhale the breath very slowly through the left nadi.
This most excellent Suryabhedana is to be done again and again. It cleanses the skull, destroys the wind diseases, and removes worm diseases.
Close the mouth. Slowly draw the breath through both nadis so it resonates from the throat to the heart. Form the kumbhaka as before. Exhale the prana through the Ida.
This kumbhaka called Ujjayi can be done walking or standing. It removes phlegm diseases in the throat, increases digestive power in the body, and destroys dropsy and diseases of the nadis and of all bodily constituents.
Inhale making the sound "seet" in the mouth, then exhale only through the nose. By engaging in this practice one becomes a second God of Love.
Respected by all yoginis, maker of creation and destruction, neither hunger nor thirst, nor sleep, nor even lethargy will appear.
The Sitkari will develop the body's vitality. The Lord of Yogis will be completely free of all disabilities on earth.
Draw in air with the tongue. Practice kumbhaka as before. Slowly exhale the air through the nostrils.
This kumbhaka named Shitali destroys enlargement of the glands or spleen, other diseases, fever, bile, hunger, thirst, and poisons.
Place both clean soles of the feet above the thighs. This is Padmasana, destroyer of all evils.
Form Pa\dmasana correctly, neck and belly aligned. Close the mouth. Expel the prana through the nose so it resonates in the heart, throat, and up to the skull. Then quickly inhale air up to the lotus of the heart (the Anahata Chakra).
Exhale and inhale in the above manner again and again. Just as a blacksmith works the bellows with speed, move the breath in ones own body with the will.
When there is fatigue in the body, inhale though the sun and quickly fill the belly with air. Hold the nose firmly without the middle and indeex fingers. Do kumbhaka in the prescribed manner. Exhale through the Ida.
This removes diseases of the wind, bile, and phlegm. It increases the fire in the body and awakens the kundalini quickly. It purifies, gives pleasure, and is beneficial. It destroys the obstructions of phlegm, etc., that exist at the mouth of the Brahma nadi.
This kumbhaka called Bhastrika is to be done with great regularity. It splits the three strong knots that form in the body.
A quick and resonant inhalation sounding like a bee; a very slow exhalation sounding like a female bee. Thus a certain bliss and delight are born in the minds of good yogis from doing Bhramari.
At the end of inhalation, hold Jalandhara tightly and slowly exhale. This one named Murccha clears the mind and gives happiness.
Move a large amount of air inside, filling the belly. Float happily like a lotus leaf, even in bottomless water. This is Plavini.
Pranayama is said to be of three kinds: exhalation, inhalation, and kumbhaka. Kumbhaka is thought to be of two kinds - Sahita and Kevala. Until such time as Kevala is mastered, one should practice Sahita.
Abandon exhalation and inhalation. Hold the breath comfortably. This pranayama is the one called Kevalakumbhaka.
Nothing in the three worlds is hard to win by one who masters Kevalakumbhaka without exhalation, or inhalation.
One made powerful by Kevalakumbhaka, from holding the breath as desired, obtains even the state of Raja Yoga. In this there is no doubt.
Through kumbhaka the kundalini is awakened. Through awakening the kundalini, the Sushumna is unblocked - and success in Hatha is born.
Raja Yoga will not be complete without Hatha, nor Hatha without Raja Yoga. Therefore practice the pair to perfection.
Make the mind without objects at the end of the retention of the prana in kumbhaka. One should reach the state Raja Yoga by engaging in this practice.
These are indicators of success in Hatha: leanness of body, clearness of face, distinctness of nada, very clear eyes, health, victory over bindu, lighting of the digestive fire, and purity of the nadis.
Thus ends the Second Chapter of the Hatha Yoga Pradipika....
Let me end by saying that while I considered myself unsuccessful in yoga, I did have when I quit, many of the indicators of health, I was thin, clear skin, bright eyes, healthy, the others I don't know. So I think it does work, even in my forties people guessed my age as in the twenties. I have from my mid fifties on started to show my true age and lose my health. As decribed in other posts I have recently been hit hard, just before my 62nd birthday, and according to the Dr. I was born with the small hole found in my heart, but never had a problem or even knew it was there until now. I never saw a Dr., except for removing tonsils, and TB xrays as a kid, then for broken ankles, and a hernia repair, since my teen years. I do attribute that to doing Yoga, (and meditation, which I never stopped), if I had kept it up, and been successful perhaps I could have been on the level described in this book, I know it does happen. We've all heard the stories.
As I said earlier, get a teacher before you do this, if you don't have one....