The purpose of this book is to help anyone involved in small-scale geophys-
ical surveys. It is not a textbook in the traditional sense, in that it is designed
for use in the field and concerns itself with practical matters – with the-
ory taking second place. Where theory determines field practice, it is stated,
not developed or justified. For example, no attempt is made to explain why
four-electrode resistivity works where two-electrode surveys do not.
