For years after her death, following each snowfall, her figure was seen walking through the snow near the Chapel. The skirt of her mourning gown trailed through the snow; but there were never any footprints.

Young says she has returned after every snowfall except for the Blizzard of '78, when drifts were so deep they prevented her return.

While the lack of snow has meant fewer opportunities for Pickman to return to the Yard, scientists have more serious concerns about weather. They must determine if the recent warm winters are part of a permanent climatic change.

Climatologist Robert E. Lautzenheiser says despite a spat of warm winters and low snowfall totals, statistics show no signs of long-term warming.

Lautzenheiser began recording temperatures and precipitation in Massachusetts for the federal government in 1956. Although budget cutbacks claimed his public funding in the early 1970s, he has continued recording weather lata.

Lautzenheiser supervises a network of unofficial weather stations and makes his measurements available to the public.

Lautzenheiser acknowledges that the Boston area has experienced several unusually mild winters in recent years. But he is skeptical of theories that the regional climate has been permanently altered.

"[Recently] we have had some fairly low snow totals...but in the last 10 years or so we have had several fairly cold winters," he says. "I wouldn't say for sure that things are changing."

Lautzenheiser's records for the past 10 years show seven winters with temperatures averaging above the normal mean of 31.3 degrees and four winters averaging below. The winter of '90-'91 was the warmest in recent memory, with an average temperature of 35.4 degrees, more than four degrees above normal.

Still, improvements in snow-removal equipment and muddled childhood memories may have as much to do with the perception that winters are warmer as higher temperatures, says Lautzenheiser.

"When you're a small child, you look up at snow mounds. When you're an adult you look down on the same piles," he says. "People have been saying [the winters have been getting milder] since Jefferson. If that were really true, then we wouldn't have snow anymore."

While Lautzenheiser tries "to keep an open mind" about global warming, Rotch Professor of the Atmospheric Sciences Michael B. McElroy says that evidence of a warming trend are undeniable.

McElroy, a close advisor of Vice President Al Gore '69, cites historic reports of the sea being frozen off the coast of Maine as evidence that the climate is changing.

"Eight of the warmest winters in the past 100 years have occurred in the last 10 years," McElroy says. What can you draw from that? There's absolutely no way to be sure."

McElroy is reluctant to say definitively that the primary cause of recent warmth is the greenhouse effect. He says there are both short-term and long-term factors which influence the climate.