Harvard's Sanitary Engineering Department recently recorded 1,000 times the normal radioactivity in Cambridge water. "When we put our Geiger counter to some Cambridge water," Harold A. Thomas, associate professor of Sanitary Engineering, admitted, "it sounded like a bobcat caught in the bushes."

This discovery marks, not as some immediately imagined, something strikingly new on the local scene, but rather another step in an age-old unceasing struggle--that between man's progress and the single sculler on the Charles River.

To understand this conflict, one must realize that through the ages the shape and form of the single scull have changed remarkably little. True, form time to time artisans have managed to make them thinner and lighter, and this year the boathouse has added a fiberglass shell. But the basic concept of rowing has not changed.

On the other hand, as man has progressed, the opposition to the sculler has armed itself with newer and more dangerous weapons. The cycle of the opposition's development, historians note, falls roughly into three overlapping periods.

The first of these is the stone age. If the stone age was at first simple, it was nonetheless irritating. Little boys stood on the bank of the Charles and threw rocks at the moving sculls. It was something of a game, with the sculler's sanity the stake. Simple in its pure form, even the stone age underwent some modernization.

First, the scullers learned to spot the little boys and row on the opposite side of the river. But the urchins were not to be fooled--they took to hiding on top of bridges and dropping rocks down on the passing shells. Since there always appears to be an abundance of little boys and big stones, this practice is employed even today.

The other day I was rowing under the Weeks Bridge when two juvenile delinquents fired.

"I got him," said the first.

"Nah, I got him," said the other.

"You both got me," I said, tossing two enormous rocks out of the scull.

Thus you see that while the stone age belongs to the past, in one form at least it is dangerously close to us today.

The second part of the anti-scull cycle is best termed the machine age. Even the most accurate of rock throwers had to remain stationary on the river side. But with the advent of Robert Fulton, the Charles River mechanized. Motor boats, big and small, appeared, oblivious to the frail Harvard students and their frail craft. If formerly one had only to row to the other side to escape a rock, now the boats and their over-present waves were all over the river. To add to the sculler's confusion, there are several types of motor boats.

First of all, there is the Chris Craft pleasure boat, which contains at least one blonde and one hairy chest. While you row they come zooming by, within sinking distance, pull out the throttle, and yell: "Hey, kid, row that boat." In order to stay afloat, of course, you must stop rowing.

Even more dangerous than the floating leather-jacket set are the sight-seeing excursion boats which look like leftovers from the Mississippi River. For something like a dollar you can get on down in Boston and travel past Dunster House, all the way up to Watertown. It is a round trip, so you actually can see Dunster House twice.

It also means they can tip the scullers over twice. The river boats, for that is what they are called on the Mississippi, have a ratio of almost two children to every adult. Since there are no rocks on the ship, they are very good-natured children.