Congress in 1876 was in an uproar. The results of that year's presidential election were the subject of bitter dispute. Republican Rutherford B. Hayes and Democrat Samuel Tilden had finished in a virtual dead heat, with cries of fraud on both sides.
So legislators, to help settle the matter, decided to snoop on United States citizens via the latest in high technology - the telegraph. They simply ordered Western Union to turn over 30,000 telegrams from important political figures.
The press was aghast at this invasion of privacy. Western Union's president refused to comply. Congress arrested him and read the telegrams anyway.
No conclusive proof of fraud was found. But the incident shows that ''high tech'' surveillance is not just a phenomenon of the 20th century. Throughout US history, experts say, the protection of privacy has depended on a mix of factors: technology, politics, and corporate attitudes.
'' 'Eternal vigilance is the price of liberty.' Some cliches gain currency and stay around, because they reflect basic truths,'' says Anthony Oettinger, head of Harvard's Center for Information Policy.
Speaking with the steady rhythm of a UPI ticker, Dr. Oettinger leans forward to make his point. Outside, students scuttle across the Harvard Law School lawn.
The leader of a group whose sole purpose is studying the information revolution, Oettinger has ''the whole wired world in his hand,'' according to Harvard magazine. He analyzes some 80 businesses - from cable television to newsstands - for their impact on the flow of data in the US.
Microchip logic, tiny video eyes, and other new-tech gadgets could complicate efforts to shield privacy, he says. But he warns against focusing on the technology itself without scrutinizing society.
''There's no doubt some things are done more efficiently with computers than with goose-quill pens. But I grew up in Europe in the '30s and '40s and saw many friends and relatives carted off by Germans using three-by-five cards,'' he says. ''It doesn't require a computer.''
Oettinger is obviously irritated by suggestions that surveillance technology, once born, creates a momentum of its own and will be used for nefarious purposes.
''That's like saying, 'Technology made me do it,' '' he says, hands waving. ''It's an absurd abdication of responsibility. There is no substitute for a free people, an electorate, whatever, remaining responsible and in charge. I mean, you've got to watch the (offenders), whoever they are.''
This does not mean that evil forces lurk just out of sight, ready to wrap the US in webs of surveillance the moment we let down our guard. Compared with both the fictional Oceania of George Orwell's ''1984'' and to many of today's totalitarian states, privacy in the US is well protected.
It does mean, Oettinger and other experts say, that we must watch for a step-by-step erosion of privacy by government agencies, corporations, and other institutions.
The benefits of new high-tech activities - from the use of computers to detect welfare fraud, to banking with electronic tellers, to on-line criminal information systems - should be weighed against possible intrusive effects.
''It's a balancing act,'' says Oettinger. ''The balance is between privacy, an important value, and a lot of other things that we might want.''
The US, since its founding, has officially prized privacy. The Fourth Amendment to the Constitution, for instance, guarantees the ''right of the people to be secure in their persons, houses, papers, and effects against unreasonable searches and seizures . . . .''
But at the same time, US society professes admiration for those who have nothing to hide, for men and women whose lives are an open book.
''There is a stress on privacy in the US, and at the same time there is a stress on openness. That helps create a tension, I think, between concealment and revelation,'' says Sissela Bok, author of the book ''Secrets.''
Mrs. Bok, a Swedish-born philosopher, is the wife of Harvard president Derek Bok. Her father, economist Gunnar Myrdal, and her mother, peace activist Alva Myrdal, have both won Nobel Prizes.
Her elegant home is near Brattle Street in Cambridge. Outside the library, evening and a late-season snow are falling as she discusses privacy, technology, and secrets.
''With computers, we are in a whole new universe with respect to (protection of privacy),'' she says. ''In this universe we probably will have to recognize that there are a number of things that can't be exactly private.''
The complexity of modern life, in other words, means that data we might prefer to keep private,such as bank balances and health records, won't be under our control.
And control, she says, is what privacy is all about - control over access to information we define as our personal domain. We thus guard our sense of identity.
''We recoil from those who would tap our telephones, read our letters, bug our rooms,'' Mrs. Bok writes. ''No matter how little we have to hide, no matter how benevolent their intentions, we take such intrusions to be demeaning.''
When our privacy is invaded, someone or something shows power over us. ''If we had no privacy at all, not even the capacity to protect it with secrets, we would be utterly vulnerable,'' she says.
But privacy for people is not the issue that most concerns Mrs. Bok. Instead, she expresses concern about government secrecy.
The Reagan administration, she feels, has tried hard to slam shut doors to much information. It has become more difficult to pry loose documents through the Freedom of Information Act, she says; Presidential Directive 84, withdrawn after being blocked by Congress, would have required many officials to sign lifetime secrecy agreements.
''I feel very strongly that there has been a tremendous move towards greater official secrecy in many areas,'' she says.
Mrs. Bok says the US already has far too many secrets. She cites studies saying that many things labeled ''top secret'' are innocuous.
The light in the library is fading. Yes, Mrs. Bok concludes, there are technologies whose intrusive potential bears watching. Yet much information is still our own.
''Sometimes people, I think, assume in this country that there is little that is private anymore, little that is secret,'' she says. ''There I just think they are wrong, actually.''