The most-remembered achievements of the 20th century, it has been argued, will be its machines. In the span of only a few decades, devices have been conceived and developed that conquered interplanetary distances, solved unthinkably large calculations, and made communications instanteous.

Unfortunately, we who live with this alleged magic are painfully aware that sunspots mess up transmissions, that it is electricity's nature to want desperately to short circuit, that belts break, gears jam and commercial aircraft are required to have triple backup on all major flight systems for excellent reasons.

The photographs received from around the world on various imposing gadgets at The Washington Post are hardly spared from Murphy's Law: if something can go wrong, it will. The serendipitous photos on these pages were created by these humming, beeping beasts which from time to time seem to tell us they have minds of their own.

Toby Massey, assistant chief of the Associated Press' Washington bureau for photography, swears his wirephoto machines hiccup only rarely, and then not because of great advances in technology.Today, an Associated Press photograph is scanned by a lesser and the information is turned into an electronic song -- low notes mean dark areas, and high notes mean light areas. The melody is sent via leased telephone lines to receivers around the country, which then decode it and, via another laser, turn it back into a picture. This works well, Massey says. What goes wrong is that the humble rollers grabbing the photograph and feeding it into the path of the laser occasionally get possessed by gremlins. Then the photo stops moving and the laser scans the same part of the picture again, and again, and again, and . . .

United Press International transmits photographs via a different technology, but their problem is similar. They have a drum the photo is put on.And the scanner is supposed to march across it at an even speed. But sometimes . . .

Consider this, then, a note to a future historian: It's true, these machines did change our lives. They allowed us to see and keep images that were unobtainable to earlier generations. Don't think of us as ingrates. But somedays, it seemed, progress was our most glaring setback.