In the novel The Sand-Reckoner by Gillian Bradshaw, Archimedes and the King's sister Delia have clandestine meetings at the Fountain of Arethusa.
Arethusa Fountain, Ortygia, Syracuse, Wikimedia Commons
The entire story can be read in Ovid's Metamorphoses
Bk V:572-641 Calliope sings: Arethusa’s story
Courtesy A.S. Kline, Ovid Translations (Poetry in Translation)
“Ceres, kindly now, happy in the return of her daughter, asks what the cause of your flight was, Arethusa, and why you are now a sacred fountain. The waters fall silent while their goddess lifts her head from the deep pool, and wringing the water from her sea-green tresses, she tells of the former love of that river of Elis.
‘I was one of the nymphs, that lived in that lived in Achaia,’ she said ‘none of them keener to travel the woodland, none of them keener to set out the nets. But, though I never sought fame for my beauty, though I was wiry, my name was, the beautiful. Nor did my looks, praised too often, give me delight. I blushed like a simpleton at the gifts of my body, those things that other girls used to rejoice in. I thought it was sinful to please.
Tired (I remember), I was returning, from the Stymphalian woods. It was hot, and my efforts had doubled the heat. I came to a river, without a ripple, hurrying on without a murmur, clear to its bed, in whose depths you could count every pebble: you would scarce think it moving. Silvery willows and poplars, fed by the waters, gave a natural shade to the sloping banks. Approaching I dipped my toes in, then as far as my knees, and not content with that I undressed, and draped my light clothes on a hanging willow, and plunged, naked, into the stream. While I gathered the water to me and splashed, gliding around in a thousand ways, and stretching out my arms to shake the water from them, I thought I heard a murmur under the surface, and, in fear, I leapt for the nearest bank of the flood.
‘What are you rushing for, Arethusa?’ Alpheus called from the waves. ‘Why are you rushing?’ He called again to me, in a strident voice. Just as I was, I fled, without my clothes (I had left my clothes on the other bank): so much the more fiercely he pursued and burned, and being naked, I seemed readier for him. So I ran, and so he wildly followed, as doves fly from a hawk on flickering wings, as a hawk is used to chasing frightened doves. Even beyond Orchemenus, I still ran, by Psophis, and Cyllene, and the ridges of Maenalus, by chill Erymanthus, Elis, he no quicker than I. But I could not stay the course, being unequal in strength: he was fitted for unremitting effort. Still, across the plains, over tree-covered mountains, through rocks and crags, and where there was no path, I ran. The sun was at my back. I saw a long shadow stretching before my feet, unless it was my fear that saw it, but certainly I feared the sound of feet, and the deep breaths from his mouth stirred the ribbons in my hair. Weary with the effort to escape him, I cried out ‘Help me: I will be taken. Diana, help the one who bore your weapons for you, whom you often gave your bow to carry, and your quiver with all its arrows!’ The goddess was moved, and raising an impenetrable cloud, threw it over me.
The river-god circled the concealing fog, and in ignorance searched about the hollow mist. Twice, without understanding, he rounded the place, where the goddess had concealed me, and twice called out ‘Arethusa, O Arethusa!’ What wretched feelings were mine, then? Perhaps those the lamb has when it hears the wolves, howling round the high fold, or the hare, that, hidden in the briars, sees the dogs hostile muzzles, and does not dare to make a movement of its body? He did not go far: he could see no signs of my tracks further on: he observed the cloud and the place. Cold sweat poured down my imprisoned limbs, and dark drops trickled from my whole body. Wherever I moved my foot, a pool gathered, and moisture dripped from my hair, and faster than I can now tell the tale I turned to liquid. And indeed the river-god saw his love in the water, and putting off the shape of a man he had assumed, he changed back to his own watery form, and mingled with mine. The Delian goddess split the earth, and plunging down into secret caverns, I was brought here to Ortygia, dear to me, because it has the same name as my goddess, the ancient name, for Delos, where she was born, and this was the first place to receive me, into the clear air.’ ”
The myth is also treated in Virgil, Georgic IV.