Here is a short account in the BSD Journal illustrates one important application of dowsing, that of dowsing for health.  

“Dowsing by the pendulum”, by Amy Goldwin.

http://www.dowsing-research.net/blog_extracts/BSD_No29_1940_p165.pdf

The author uses her dowsing pendulum to determine the “vitality” of her subject in a very simple manner. She holds the pendulum over the subject, to obtain first that she refers to as the subject’s “vibrations” (a reference to the idea in her time, that the dowsing reaction was some sort of radiation). This initial step she could also perform from photographs (akin to map dowsing), or even handwriting. Next, she held it over a protractor, and the line of swing of the pendulum coincided with a number, from 0 to 180 degrees; the lower the number, the poorer the overall health of the subject. She could also identify further insight into the prevailing ailment, by repeating the exercise, but this time holding the pendulum over the protractor, while pointing to organs on an anatomical chart. She could also simply hold her pendulum over the person or their proxy and obtain an insight into the subject’s state of health from one of four response.

This is another example showing that, as has been noted previously, the dowsing reaction can be programmed, and furthermore the response can be calibrated against an arbitrary tool.  (Another instance is the use of a coloured chart when water divining to deduce the purity of the water, eg black might indicate brackish, blue perhaps fresh water). Here a protractor is used, with the advantage that the response can be converted into a (relative) numerical value.

In addition to testing, she dowsed for remedies. She apparently had a range of these, each of which she would dowse over until the pendulum showed the largest swing. How the chosen remedy related to the ailment is not clear, but since some of the remedies were homeopathic, and perhaps her observation that the a remedy did not always correct the same issue, then maybe the healing effect (as determined by her pendulum), might relate more to her intention to heal.