Secluded Dunbar Laboratory Studies Earth's Composition, Professor Birch Heads College's Geophysical Research

The Dunbar Laboratory is a small inauspicious building in the far reaches of the University, which resembles a garage station more than a college engineering lab.

A confusing mixture of a 30-year-old artillery building and a bright shiny 1953 addition, Dunbar houses Harvard's experiments in geophysics, particularly the work of Francis Birch, Sturgis Hooper Professor of Geology. Originally Dunbar was used as an artillery shed during the first world war; since then it has been deeded over to science, and outdated relics of the militia have been replaced by high-powered compression machines as Birch and his small staff delve into the problems of the earth's inner composition.

The man who runs Dunbar, his offices upstairs, his machines downstairs, seems almost caught between the academic life and the work of a scientist. The upstairs rooms are clean and orderly. Downstairs there is machinery, the walls are not so shiny. Birch's own dress, a plaid tie and oxford shirt, partly concealed under a mechanic's apron, reveals part of a double life.

Back in 1931 when the study of geophysics--or the earth itself--was about to be expanded, the leading Harvard pioneers in the Geology department were Professors P. W. Bridgman and Reginald A. Daly. Daly and Bridgman, along with a committee of other faculty members, and financial aid from the Rockefeller Foundation and the Geological Society of America organized an investigation. But the first step was the selection of a leader, since both Daly and Bridgman were occupied with their own work.

According to a departmental pamphlet, "Geophysics at Harvard," the future of that field depended on finding a man with an unusual combination of talents: "he must be able to direct his energies into new channels which would be most productive of important geophysical results; he must be highly trained in a rare field of specialization--classical mathematical physics, elasticity and hydrodynamics; he must be able to work with his hands to develop high pressure apparatus which would operate at high temperature, and devise means for electrical measurements of great delicacy which would function under these abnormal conditions."

Birch the Man

They chose Birch, then just an up and coming young physicist who had worked with Bridgman, now a leading man in the study of the combinations of pressure and temperature. With his changing staff--usually between four and five men--Birch has in most recent studies virtually disproven an old theory on heat convections causing mountains and at the same time advancing the study of the earth's pressures.

Since he has been working at Dunbar, Birch, with his powerful impressive machinery has been able to reproduce duplicate pressures of conditions 600 miles below the surface of the earth.

In another series of experiments, the group has made great progress in interpreting the seismologist's wave signals--from laboratory work--trying to determine the velocity of earthquake waves in rocks under certain conditions of temperature and pressure. Because of this seismologists are able to examine records of underneath wave velocities with increasing knowledge about the nature of the material through which the waves pass.

Actually earth heat itself is still the most important unknown of geophysics. The only known source of energy which is potent enough to contort the earth's surface with upthrust mountains, heat must be studied by the geophysicist in order to gauge rocks' conductivity.

Down below the surface two miles or so, the temperature can be determined from specially designed thermometers which have been sunk into bore holes. Estimates below that depend on the knowledge of the rock forms. Such investigations have enabled the scientists to systematize knowledge of the conductivity of any rocks from mineral composition.

In fact, while he will not outright admit to disproving it, the somewhat close mouthed Birch does confess that he and his researchers have made the theory that convection current beneath the earth's surface are related to the mountains, "highly improbably."