Bits and pieces, I thought as I circled round and round, high above the airport. It was one of those days two weeks ago when winter was making its last stand, with snow that was followed by cold and lake effect squalls. Not a great day by any stretch of the imagination, but as good a day as any for a test flight.

It was the first flight for the engine that I had been assembling in fits and starts for most of the winter. We had started it and made all the basic checks of the fuel, oil, ignition, electrical, and vacuum systems and buttoned it up for flight. I took off and made a gradual climb, circling the airport, and leveled off 3000 feet above it. Prudence dictates that the first hour of flight for a new engine is done within gliding distance of home.

If it is a good flight, it is a boring flight, with nothing to do but hold a circle overhead and write down temperatures and pressures every few minutes. I wandered off as the plane droned along, and admired the clouds just to the north. They were full of snow, and the lowest layer was right at my altitude. As they blew across from west to east they dragged veils and curtains of snow along underneath them. In between the squalls, I could look beyond and see higher clouds and patches of blue sky. The sky was torn into bits and pieces of weather, good and bad.

The visibility was fairly good in directions where it wasn't snowing. From my perch high above the valley I could see the hilltop where I spent several years cutting firewood in younger times. Just to the north of the hills I could see Painted Post, where my mom's folks spent their adult lives. I could see up as far as Seneca Lake, on a line of sight over my house, and I wondered what the rest of the family was up to. I looked to the ridge that runs north from Horseheads and could see where my grandfather was raised.

I was raised on Long Island, but I was now circling over the airport where my dad took my mom for her first airplane ride when they were courting. For that matter, part of the airport is built on the farm that belonged to great- great grandparents of mine. "Circles among the bits and pieces," I mused as the plane droned round and round.

Things go back much further than that, though. The Elmira airport is built on a very unusual piece of ground, in a river valley that has no river. The Chemung River makes a right turn at Big Flats and proceeds to Elmira through a narrow gorge which it cut through bedrock during the times when the last glaciers were receding. From Big Flats to downtown Elmira, the valley floor is wide and flat, cut only by the flow of feeder creeks.

Horseheads lies at the junction of the Seneca Lake trough and the old Chemung River valley. For a period, the tip of the receding glacier blocked the river's flow through the area, and the waters backed up so high that the river found a new course to the south of Harris Hill. I looked down at the steep walls of the gorge and the torn surface of the "devil's washboard" along its south face and tried to imagine the violence of this event. When the glacier finally retreated, it left a gentle fill of gravel and debris which forced the river to keep its new course. Harris Hill, isolated between the preglacial and postglacial river valleys, is technically an "Umlaufberg", or "runaround mountain"

There are so many bits and pieces that come to you through the windows of the airplane, it is almost magic.

I couldn't help but think of the magic closer to hand from time to time. Just a few feet in front of me were a whole bunch of little bits and pieces that I had assembled into an engine. The pistons, fairly weighty parts, being flung wildly back and forth, accelerating to 170 MPH and slowed to a stop eighty times a second. I thought about the connecting rod bolts. Then there is the "Jesus bolt" that secures the little gear that drives the fuel pump, oil pump, camshaft, and magnetos. The maintenance manual spends two pages to describe just how this gear is to be secured to the end of the crankshaft. I thought of that, too, but when I was building the engine, I knew that I would be thinking of these pieces again. I'll think of them yet again, hopefully for a long time, each time that a friend flies that plane.

It is not every job that has you putting an engine together, bolting it onto an airplane, and then flying it through thin air. Its kind of an interesting ride, even if it does only seem to go around in circles.

To contact Bob Tilden, send an e-mail.