The purpose of this new instrument is to aid in the search for valuable mineral deposits.

The history of the instrument culminates in an intensive testing period of 2½ years, during which time it has been tested in the field in Arizona, Mexico, New Mexico, Texas, Oklahoma, Arkansas, Kansas, Missouri, Illinois, and Wisconsin.

In principle the instrument is designed to measure slight variations in the earth's magnetic field.

The construction of the Superdip is designed to withstand rough field use.

Its manipulation has been simplified to the utmost extent commensurate with reliable results.

The corrections for very precise work are made by eliminating the effects of temperature, diurnal variation, latitude, and longitude.

The sources of error, including manipulative, mechanical, and magnetic sources, have been evaluated as closely as possible to date.

The field procedure routine has been evolved to eliminate lost motion.

The application of the instrument to the oil business is exemplified by a picture of the results of a survey made in the Panhandle of Texas, drawn in isometric form.