Sam Worden

Sam Worden

Biography Citation for the Reginald Fessenden Award 1974

The Society of Exploration Geophysicists has chosen as the recipient of the SEG Medal for 1974 a fine gentleman and a rare instrumental genius. The revolutionary new instrument which he invented and built is as popular today as it was at the start more than 30 years ago. The instrument is well identified with his name all over the world where geophysics is practiced. I am proud and happy to bring this man before you today for well-deserved official recognition of his important contribution to our profession.

Fifty years ago, in the earliest days of applied geophysics, (when our medalist was a little boy growing up on a farm in Kansas), the principal method was gravity exploration. The instruments used at that time were the Eötvös torsion balance and the gravity pendulum. Spectacular successes were achieved. But field work was arduous and slow with bulky and heavy apparatus. Suddenly, in the middle '30s a new era in gravity exploration arrived with the invention of the so-called gravimeter (or gravity meter) which maps geologically significant changes in the earth's gravity field by observing a mass suspended on a spring. We can think of this as a highly refined version of the common peddler's spring balance. The gravimeter was a giant step forward and the pendulum and torsion balance were quickly shelved. However, the new gravimeter was delicate and bulky and required two men and a special vehicle for field handling. Nevertheless it gave tremendous impetus to gravity exploration.

Another spectacular development, although hardly imaginable at the time, was not long delayed. This was a gravimeter constructed entirely of fused quartz and enclosed in a partially evacuated chamber which was submerged in water for very stable temperature control. This instrument, designed by Dr. Mott-Smith, professor of Physics at Rice Institute, was more accurate but still rather difficult to transport and use under field conditions.

Some years later an ex-student and ex-employee of Dr. Mott-Smith, realizing the need for portability of gravity measuring instruments, began experimenting with temperature compensated fused quartz systems to replace the large power consuming thermostated instruments. The result was the Worden meter weighing in at just over five pounds and requiring no external batteries.

"Two views of the Worden Gravimeter. SEG Museum Collection."

The early days with the Worden Gravimeter (as it immediately was named) were not easy. The first instruments were built in a small garage at the Worden's residence1. But the field results were spectacular. I had occasion to call attention to this achievement in a paper "Modern Developments in Gravity Exploration" at the 75th Anniversary celebration of the Colorado School of Mines. The establishment of the Houston Technical Laboratory soon followed in a new building with living quarters attached, and the fame of the Worden Gravimeter and the charming southern hospitality of Sam Worden and his beautiful, talented wife, Helen, spread quickly.

Today thirteen years later the Worden Gravimeter continues in worldwide use. No significant improvement has been needed. This is all the more remarkable in view of the revolutionary advances in geophysical instrumentation which have dominated the recent decades. Gravity exploration without the Worden Gravimeter is unthinkable!

It is an honor for me to be spokesman for our profession in presenting the SEG Medal for 1974 to my long-time friend Sam Worden. Sam, this medal is a token of the sincere esteem of all your geophysical colleagues and of your many, many friends. My hearty congratulations. Written by: Sigmund Hammer

1Mrs. Helen S. Worden respectfully states that the developmental stages of the gravimeter happened within a dust-free laboratory located at their residence, while the Houston Technical Lab was being built. The new lab was to have special facilities that were necessary for the final construction and testing of the completed model.

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