And then, with your feet together and your eyes on the horizon, you hit the ground. Upon impact, you collapse and roll.

The blissful descent is over. You get up exhilarated and proud, and it all seems worth the worry. The amount of your happiness equals--at least--the amount of your fear beforehand. And, as my friend declares, you feel that "Your perspective is restored. You just don't exaggerate petty things after you've parachuted."

It is my conclusion, then, after looking back on my one and only jump, that the experience of parachuting can get through to you pretty deeply. It can force you in on yourself as never before, and it can take you away from yourself--for four seconds--as never before. It isn't all terror, nor is it all thrill. Nor does the adventure last for only the few minutes of decent from exit to landing.

It begins with your decision to go and, certainly it continues as a sharp memory for the rest of your life. Each man can treat the adventure in retrospect as he wishes, whether that be by philosophizing boasting, or remaining sober about it, for it is, ultimately an extremely individual experience.

Beyond the basic curiosity, motives vary. Some jump because they think that the good life must have frequent bouts with danger; others do it for therapeutic reasons in times of despair. A few do it to prove to themselves--and, perhaps, to others--that they are men. And, of course, there are those who just seek the thrill.

The experienced jumpers seem to be the only bunch of guys who assume the by-products of the "crisis", and concentrate on the various skills such as free-fall position (before the parachute opens) and landing on target. For this reason, they seem to be the only people who see it as a sport.

That they concentrate on technique rather than trauma does not mean of hazard, however. They, like the nervous beginners, know that accidents can happen.

What about the danger? How safe is sport parachuting? Like riding in airplanes or even in cars, it's not 100 per cent foolproof, though the statistics are overwhelmingly in favor of your coming out alive.

The man who convinced me of the statistical advantage and therefore talked me into jumping is Nick Soutter, a junior from Dedham who lives in Adams House. He has done more to promote sport parachuting at Harvard than all other skydivers at the College have done since 1957, when the Crimson won this country's first intercollegiate parachute tournament.

(Sport parachuting was brought to this country from France in 1956 by Jacques Istel.)

Here are some of the things that Soutter pointed out to me: You jump with an emergency parachute on your chest which you deploy in case of a malfunction in the main canopy. On your first five jumps, in accordance with Parachuts Club of America regulations, you use a static line, which means that your rip cord is pulled for you as soon as you leave the plane.

There have been over 5,000 sport parachute jumps made at Mansfield--and at least that many at Orange--resulting in no fatalities whatsoever. Last year there were 60,000 jumps made in this country, resulting in six fatalities--none of which attributable to parachute malfunction (a suicide two drownings, two "freezes" on non-static-line jumps, and one electrocution resulting from a landing in high wires.)

In the seven years of jumping in Massachusetts, one of this country's leading parachute centers, there has been only one death--the birthday cake drowning of last September off Plum Island.

Soutter, a New England safety officer licensed by the P.C.A., told me that he had taken 489 students through static-line jumps--in none of which did the main canopy fail. And he showed me how a parachute works, how the several tough, elastic bands throw the pack open when the rip cord is pulled, and how, at the same instant, the pilot chute (a miniature parachute that pulls the main canopy out) hurtles almost 20 feet into the air by the force of its own compressed spring system.

It was all very convincing. So I jumped from a Cessna 182 at 2500 feet with a 28-foot "skydiver" parachute over the Mansfield airport grounds. Mansfield is the headquarters for the Cambridge Parachute Club, the oldest club of its type in the country, having been formed in 1957.