Gilbert Gude has an eye for philosophy that has served him well -- in the halls of government and out.

He spent 10 years in the Maryland legislature, and 10 more in the U.S. Congress, representing Montgomery County. For the past eight years he has served as director of the Congressional Research Service at the Library of Congress.

But the mountains of pamphlets and propaganda and memoranda he has seen in his various careers have not obscured Gude's outlook on life.

"You have to look at the big picture," Gude, 61, said, "put it in perspective."

And in his first book, a newly published history of two Potomac River valley coal-mining towns, Gude brings into sympathetic focus both the speculators who hammered empires of coal out of the mountainsides and the miners, whose dark shifts underground were passed along from father to son like inheritances.

"I was raised on the work ethic," Gude said half-apologetically, and grew up "a romantic."

Published by Seven Locks Press of Cabin John, "Where the Potomac Begins: A History of the North Branch Valley" had its own source in a 400-mile fact-finding trek that Gude, cofounder of the House Environmental Study Conference, led along the Potomac in 1975.

In the river valley along the West Virginia-Maryland border, Gude discovered an Appalachian coal-mining district he describes as an example of the "great web" tying the economy, technology and ecology together.

"Learning about the Upper Potomac," he writes in the preface, "has been, for me, a search for congruence among politics, history, science, literature and poetry."

Gude spins an ecological cautionary tale through the history of two mining towns, Kempton, Md., and Elk Garden, W.Va. An amateur archeologist, he treats them like digs, turning over artifacts of anecdote and memory. But like a good political speech, the book segues into a plea for environmental legislation.

"Those mines were an integral part of the development and economy of Western Maryland," Gude said. "But now we have to harness the same intelligence and will . . .to solving the problems of air pollution" that is produced in part through the burning of that very coal.

The Library of Congress' massive photography section provided an unexpected trove for Gude that is the centerpiece of "Where the Potomac Begins."

"I thought there might be a couple of pictures of miners in that area, but we turned up this cache of pictures taken by John Vachon for the Farm Security Administration," Gude said.

"I wish we could have used them all; they're about 80 altogether."

The photos were taken in 1939 during a precontract-signing strike by Kempton miners, an annual affair by Kempton miners. Idled workers lounge in the company store or the post office, or play cards outside the mine; three small boys pull their wagon through a slag heap looking for chunks of coal to take home.

There is a particularly arresting set of portraits of the Blizzard family: George, the miner father, his close-lipped mouth suggesting the broken and stained teeth of Depression-era workers; his straight-browed and steady-eyed wife, and several children, including one irresistible Artful Dodger and a small girl whose eyes are already dark with suspicion.

A certain eccentric coherence runs through Gude's conversation. From his family's nursery business and a wartime stint in a Naval laboratory that nearly converted him to entomology, to his horticultural studies at Cornell University and his environmental activism in Congress, his work has reaffirmed his faith in the historical overview.

He is already launched on another book with the same outlook, a study of five towns between Paw Paw and Shepherdstown, W.Va., along the next stretch of the Potomac. "I'm concerned with the future of the small community in the culture and economy of these times," he said.