The eclipse plunged the snow-covered prairies in Central Montana into darkness for slightly more than two minutes. The intensity of storms on the sun resulted in a spectacular display of flaming prominences from several parts of the solar disk at totality. Outside the fringe of solar storms, the ghostly white corona sprang into view, displaying many irregular spikes.

The stark, rolling snowfields reaching to the peaks of the Rocky Mountains on the horizon added to the drama of the show.

In the last few seconds before the dark outline of the moon completely covered the sun, a great bluish mass seemed to sweep across the snow, swiftly darkening the scene into night and leaving a brilliant orange sunset on the horizon. The planet Venus suddenly came into view not far from the eclipsed sun.

More than 500 astronomers and other eclipse enthusiasts riding in 15 buses selected a remote vantage point at the last moment, parking by the side of a country road near an abandoned farmhouse. The group's organizers, including two meteorologists, a former astronaut and a network of ham radio stations, coordinated information to guide viewers away from approaching storms and overcast skies. At the last moment, the eclipse was nearly obscured to some of the ground viewers by a group of hot-air balloons flown by eclipse watchers.

Anxious astronomers yelled to the balloonists a few hundred feet above the ground to change altitude, and the balloonists obliged.

At totality on the ground, the red prominences and white corona were so striking that an appreciative murmur swept over the crowd. Seasoned eclipse watchers, including astronomers in the group, agreed that today's show was one of the best they had seen.

As usual, the temperature fell sharply during today's eclipse, and the bitter cold numbed photographers' fingers.

Watchers took to skis, cars, airplanes, balloons and mountain trails to look at the eclipse, which was total in an arc starting in the Pacific Ocean and funning northeastward through Washington, Montana, Manitoba, Canada, and the Arctic. Elsewhere in the continental United States, the eclipse was only partial. In New York City, 61 percent of the sun's disk was covered by the moon.

The bus caravan, which carried the largest single group of watchers, was organized by Dr. Philip Sigler, a professor of sociology at the City University of New York, with his wife and brother-in-law, Dr. Theodore Pedas, planetarium director at Youngstown State University in Ohio.

The Siglers have organized eclipse expeditions on ships and land since 1972, all of which have successfully evaded bad weather and other obstacles to convey large numbers of enthusiasts and professional astronomers to the best vantage points…

This year, they had hoped to use some 200 miles of Montana railroad to chase the eclipse, but negotiations for a special Amtrak train failed at the last moment. A bus caravan operating from Big Sky was used instead.

Experts on today's expedition included Dr. John A. Eddy, solar astronomer at the High Altitude Observatory in Boulder Colo.; Dr. Mark R. Chartrand 3d, chairman of New York City's Hayden Planetarium, and Dr. Frank D. Drake, director of the National Astronomy and Ionosphere Center at Arecibo, P.R.

Dr. Edward M. Brooks, professor of geophysics at Boston College, maneuvered the convoy of buses through the snow-covered mountain passes and range land of western Montana near Yellowstone National Park, plotting tactics against the weather like a general up against a wily and unpredictable enemy.

With much of the North American continent under overcast, the task of finding a hole in the clouds large enough to look at the sun for two minutes proved a formidable task. For days in advance, Dr. Brooks, the meteorology guide on previous eclipse expeditions the group has made, plotted weather data and made dummy eclipse-chasing runs.

He reported to participants last night that of three dummy passes he made during the last three days, viewers would have been able to see the eclipse on only one, but that he had learned about some peculiarities of local weather in the process.

"It looks as if we have a fighting chance of seeing the eclipse," he announced at a final weather briefing. "Unfortunately, our [astronomer] friends in Canada are not going to be so lucky. The overcast will probably cover them completely."

Dr. Brooks led the 15-bus convoy, escorted by sheriff's cars, from a radio-equipped jeep in continuous touch with weather stations in various parts of the country and with several aircraft in flight including one in which the former astronaut M. Scott Carpenter was sending direct weather reconnaissance.

The overcast in Canada, besides being deeply disappointing to thousands of people along the path of totality in Manitoba Province, was especially unlucky for a research team from Williams College in Williamstown, Mass.

The Williams team was headed by Dr. Jay M. Pasachoff, whose observations of the sun's corona during this eclipse were planned to yield data on the density of plasma within the huge shell of ultrahot gas surrounding the sun.

Plasma is gas in which normal atoms have been stripped of some or all of their electrons, thus becoming ions. This commonly occurs in extremely hot gases such as the solar corona, whose temperature is about 1 million degrees Fahrenheit. The plasma in the solar corona is strikingly similar to the plasma that would have to be heated, compressed and confined in a fusion reactor here on earth, and the irregular behavior of the sun's corona could hold clues to the proper design of a workable fusion reactor.

Dr. Pasachoff's observation point was among the more comfortable to be had by scientists observing this eclipse. He and his students sat on the balcony of the physics building of the University of Brandon in Manitoba.

Although there was a thin cloud cover. Dr. Pasachoff said in a telephone interview, he was able to make usable measurements of the density of plasma at about 40 points throughout the corona before totality ended. His goal is to produce a map of coronal density variations. He said each eclipse added to such knowledge because the densities change in accordance with the 11-year sunspot cycle.

This time, he said, he saw a number of condensations, isolated regions of unusual brilliance in the corona where densities were unusually high.

Eclipses are not particularly rare. In the average century there are 237 solar eclipses, which includes 66 total solar eclipses, and 154 lunar eclipses, including 71 total lunar eclipses. But most of these are in out-or-the-way places, and many people pass their lives without seeing one.

Allowing for the fact that in a total eclipse the path of totality is about 100 miles wide, a total eclipse of the sun is visible from the same spot on earth only once every 360 years.

During the last century or so, astronomers have been able to go to remote eclipses intentionally, rather than having to wait for each one. Shipborne astronomy added many more eclipses to those to which land-based observers had been limited, and the airplane and space vehicles have still further expanded access to eclipses.

Consequently, there has been an explosion of knowledge about eclipses and the sun in recent years.