HE who cuts his own firewood is warm twice, so the saying goes. To say the same of him who builds his own igloo is, well, stretching it.
Cutting Styrofoam-like blocks of Arctic snow to build a geodesic polar dome, or digging into a berm at the base of an iceberg to hollow out a snow cave, is an extremely effective way to bring feeling back to feet and hands. But the heat stops there.
After the hard, active work is done, warmth comes through a mixture of radiation, insulation, and imagination.
The savvy snow camper can squeeze temperatures out of the Arctic the way a bushman can water from the Kalahari desert. Digging down to sea ice or bare ground releases radiant surface temperature - roughly 28 degrees F here. Snow insulates well if cut into blocks at least 8 inches thick. A small entrance, dug lower than the sleeping platform, traps the coldest air in a sump; a block wedged tightly into the entrance prevents draft. Candles or Sterno will give a few more degrees, but require ventilation.
These measures should produce an inside temperature of about 20 degrees F - not warm enough to keep the rent board off a landlord's back, but an improvement over windchills, snow storms, and other Arctic treats. (Try not to exceed 32 degrees F inside, or the walls will ice up and conduct cold from outside.)
A well-built snow shelter is one of the most satisfying accomplishments to be had in the Arctic. Preparing to sleep in it is one of the least welcome of northern prospects. True comfort requires stripping to the skivvies in temperatures nippier than a tangled team of hungry sled dogs.
The Arctic explorers of old, unequipped with modern luxuries such as synthetic wicking clothes and goose-down sleeping bags, knew that it was what they slept on, not under, that counted most. If they only had one caribou hide, they put it under them.
So, after several minutes of mental preparation and a vigorous walk to crank up body heat, the survivor plunges belly-down into the icy blue interior of his chamber, plugs the door, and sheds his clothing. He puts his heavy parkas and ``fat-boy'' snow pants under his sleeping bag. Once in the cold crusty bag, he quickly draws tight the opening, leaving only his nose and mouth to protrude. But he must cover these, too, with a cloth to keep his breath from dampening the bag. If he doesn't, a coat of ice will develop on the bag, and if he has built his ceiling too low, his breath will rebound off it and snow on him during the night.
Then, conscious only of having to repeat this process in reverse the following morning, the survivor rubs his feet together to stop the stinging and, if all else was done right, drifts off.