莱昂纳多想象第一个。下一个是阿宝le lathe with a drive cord, illustrated in Plumier's L'art de tourner en perfection. Then Ramsden, Vauconson, the great Maudslay, his student Roberts, Fox, Clement, Whitworth. The long line of machinists to my left lean into their work, ungloved hands adjusting the calipers, tapping the bit lightly with their fingertips. Each man withdraws into his house of work: the rough cut, shearing of iron by tempered steel, blue-black threads lifting like locks of hair, then breaking over bevel and ridge. Oil and water splash over the whitening bit, hissing. The lathe on night-shift, moonlight silvering the bed-ways. The old man I apprenticed with, Roy Garcia, in silk shirt, khakis, and Florsheims. Cautious, almost delicate explanations and slow, shapely hand movements. Craft by repetition. Haig and Haig behind the tool chest. In Diderot's Encyclopaedia, an engraving of a small machine shop: forge and bellows in back, in the foreground a mandrel lathe turned by a boy. It is late afternoon, and the copper light leaking in from the street side of the shop just catches his elbow, calf, shoe. Taverns begin to crowd with workmen curling over their tankards, still hearing in the rattle of carriages over cobblestone the steady tap of the treadle, the gasp and heave of the bellows. The boy leaves the shop, cringing into the light, and digs the grime from his fingernails, blue from bruises. Walking home, he hears a clavier? Couperin, maybe, a Bach toccata?from a window overhead. Music, he thinks, the beautiful. Tavern doors open. Voices. Grab and hustle of the street. Cart wheels. The small room of his life. The darkening sky. I listen to the clunk-and-slide of the milling machine, Maudsley's art of clarity and precision: sculpture of poppet, saddle, jack screw, pawl, cone-pulley, the fit and mesh of gears, tooth in groove like interlaced fingers. I think of Mozart folding and unfolding his napkin as the notes sound in his head. The new machinist sings Patsy Cline, I Fall to Pieces. Sparrows bicker overhead. Screed of the grinder, the bandsaw's groan and wail. In his boredom the boy in Diderot studies again through the shop's open door the buttresses of Suger's cathedral and imagines the young Leonardo in his apprenticeship staring through the window at Brunelleschi's dome, solid yet miraculous, a resurrected body, floating above the city. Outside, a cowbird cries, flapping up from the pipe rack, the ruffling of wings like a quilt flung over a bed. Snow settles on the tops of cans, black rings in a white field. The stock, cut clean, gleams under lamplight. After work, I wade back through the silence of the shop: the lathes shut down, inert, like enormous animals in hibernation, red oil rags lying limp on the shoulders of machines, dust motes still climbing shafts of dawn light, hook and hoist chain lying desultory as an old drunk collapsed outside a bar, barn sparrows pecking on the shores of oil puddles? emptiness, wholeness; a cave, a cathedral. As morning light washes the walls of Florence, the boy Leonardo mixes paints in Verrocchio's shop and watches the new apprentice muddle the simple task of the Madonna's shawl. Leonardo whistles a canzone and imagines a lathe: the spindle, bit, and treadle, the gleam of brass.