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Anyone out there who knows more about optics than I do and would be willing to beta-read the scene below the cut for egregious errors? Scenario involves someone trying to explain prisms and dispersion to a young child, while trying not to overwhelm her with detail. ETA — no one else responded, and Andrew seemed to think it was ok, so I’ve gone ahead and posted it. Any errors are mine and not Prof. Barker’s.
Mindful of the oily smell of the mimeograph ink, Noah had set up a couple of card tables in the shed in the back yard, where they could work at the posters for Save Our Streams. The mimeograph sat on one table. At the other, Angela perched on a chair, coloring in the printed posters with tints from her watercolor paintbox. Just now she was working, with an expression of the utmost seriousness, on the fish-and-stream image Noah had carefully scratched into the stencil sheet, along with the larger letters at the top of the poster. Across from her sat Professor Barker, coloring posters also, his expression equally grave and further enhanced by the glasses perched halfway down his nose. Angela raised her eyes from her poster to glance at his efforts:
“Fish aren’t red.”
“Some are. Anyway, fish don’t have purple outlines around them, but the ones on the poster do, so we might well color them however we like.”
“My fish are blue and grey. Most fish I've seen are blue and grey. Except goldfish, but they don't live in the streams here.”
“Have you ever seen a live trout?”
“No.”
“Beautiful sight. Their scales are iridescent.” The professor paused, then added by way of explanation: “They reflect a spectrum of colors.”
Angela gave him a long, quizzical look, reminding him very much of her mother, before finally asking:
“All right. What's a spectrum?"
The professor was pleased that for once someone was asking him the kind of questions he liked answering, but the exchange had reminded him how inexperienced he was at explaining things to the Very Young. Then again, Angela wasn’t the Very Young, she was Noah and Debra’s daughter; he’d known her since she was born. He considered how to begin.
“You know the paperweight on the coffee table in your parents' living room?” he asked.
“The one that looks like a big diamond?”
“Yes. What color would you say it is?”
“All different colors. Rainbow.”
“Exactly,” said Lionel, pleased the child had already made the connection. “But is the color in the paperweight itself? I mean, is it stained glass, like a church window?”
Angela frowned silently. A thinking look. He guessed she was picturing the crystal paperweight in her head, and remembering how—
“No,” she said. “I don’t think so. Because the colors change if you tilt it, and they wouldn’t do that if it was stained glass. The cruet set on the sideboard is stained glass, and it's always red, so matter how you look at it.” The professor nodded.
“So— if the paperweight is clear, what makes the colors?” The little girl frowned again.
“Just a minute, I’m going to go get it so I can look at it while I’m thinking.” She jumped down from her chair and scampered away. Prof. Barker resumed coloring, humming to himself as he worked.
Debra’s voice drifted from a window in the house:
“If there’s no Bureau of Fish, Game and Wildlife in this state, do we try the Department of Health, or the American Scenic and Historic Preservation Society?”
“How about the State Department of Environmental Conservation Police?” came her father’s reply.
Angela returned, bearing the paperweight in both hands. She lifted it and set it carefully on the edge of the card table before squirming her way back up onto the chair. Barker reached across the worn baize surface and slid the paperweight to the center of the table, between them.
“What do you notice about it? Besides the color.”
“It was heavy to pick up and carry.”
“That’s because it’s crystal —lead glass— not regular glass. Adding lead makes the glass easier to cut and polish. Gives it a higher index of refraction— that means, it makes it shinier,” he added.
“—and is the shininess what makes the colors?” Angela asked, interested, but also politely nudging the conversation forward, as she’d seen her mother do when someone took too long to get to the point.
“Not quite.” Lionel paused, wondering how to condense Newton for a six-and-a-half-year-old (and without veering off into Einstein). “All the colours we can see,” he said, “are light, at different wavelengths.” He hesitated, casting about for an analogy based in one of Angela’s interests. If he compared colours to radio frequencies, she’d ask why a rainbow wasn’t a cacophony. What a bloody mess he’d got himself into, just trying to describe the shimmer of fish scales. “The baize on this table looks green, because when the sunlight hits it, it absorbs all the light that isn’t green, and only the green light bounces back for our eyes to see.”
Angela stroked the surface of the table-top.
“Clear materials,” Lionel went on, “like glass, or water, are clear because the light passes through them. But sometimes they let more of some colors through than others. And if the clear material is a certain shape— like the angles on that paperweight —it disperses light— er, it sorts it out into the spectrum of different colours.” The little girl tilted her head.
“Oh,” she said. “Why didn’t you say a spectrum was the same thing as a rainbow?”
All of a sudden, she reminded the professor very much of her father. He pulled out his handkerchief and mopped his brow, slightly startled by the relief he felt at seeing something of Noah in the child. Lionel had never doubted the attachment between Angela and her father; Noah wouldn’t care what anybody thought; and Debra could silence gossips with a polite, chill glance; but the little girl was at school now, old enough to overhear things. At least she didn’t not look like Noah; her dark hair could have come from him. Most gossip, Lionel hoped, would be about her slightly premature birthday, and not about a troubled young woman who had—
“So? Tell me about the fish scales.”
“Eh?”
“The fish scales you were talking about earlier, before we went on to this. Do they reflect colors, or do the colors go through them like the crystal paperweight?”
“Hullo, you two— holding a seance?” Noah had come out on the verandah, followed by Bobby and Beelzy. “Anna’s made up a pitcher of lemonade. Darling, be careful you don’t pinch your fingers in the table-leg bracket.” This last comment was to Angela as she gripped the edge of the table to swing herself down from her chair. Landing safely, she looked back up at Lionel:
“Are you coming? You can tell me about the fish scales in the kitchen.”
“Noah, dear boy,” sighed the professor as he got up from the table, “children are exhausting. I don’t know how you and Debra do it.” He picked up the paperweight and handed it to his friend.
Ahead of them Beelzebub, Angela, and her little brother ran towards the house, almost neck-and neck until they reached the back porch, where the four-legged creature bounded up the stairs, the girl climbed them more sedately, and the toddler laboriously made his way up by holding the balusters that supported the handrail too high for him to reach. The analogy I needed, Lionel thought.
“Something funny, old chap?”
“Just l’esprit de l’escalier.”
Mindful of the oily smell of the mimeograph ink, Noah had set up a couple of card tables in the shed in the back yard, where they could work at the posters for Save Our Streams. The mimeograph sat on one table. At the other, Angela perched on a chair, coloring in the printed posters with tints from her watercolor paintbox. Just now she was working, with an expression of the utmost seriousness, on the fish-and-stream image Noah had carefully scratched into the stencil sheet, along with the larger letters at the top of the poster. Across from her sat Professor Barker, coloring posters also, his expression equally grave and further enhanced by the glasses perched halfway down his nose. Angela raised her eyes from her poster to glance at his efforts:
“Fish aren’t red.”
“Some are. Anyway, fish don’t have purple outlines around them, but the ones on the poster do, so we might well color them however we like.”
“My fish are blue and grey. Most fish I've seen are blue and grey. Except goldfish, but they don't live in the streams here.”
“Have you ever seen a live trout?”
“No.”
“Beautiful sight. Their scales are iridescent.” The professor paused, then added by way of explanation: “They reflect a spectrum of colors.”
Angela gave him a long, quizzical look, reminding him very much of her mother, before finally asking:
“All right. What's a spectrum?"
The professor was pleased that for once someone was asking him the kind of questions he liked answering, but the exchange had reminded him how inexperienced he was at explaining things to the Very Young. Then again, Angela wasn’t the Very Young, she was Noah and Debra’s daughter; he’d known her since she was born. He considered how to begin.
“You know the paperweight on the coffee table in your parents' living room?” he asked.
“The one that looks like a big diamond?”
“Yes. What color would you say it is?”
“All different colors. Rainbow.”
“Exactly,” said Lionel, pleased the child had already made the connection. “But is the color in the paperweight itself? I mean, is it stained glass, like a church window?”
Angela frowned silently. A thinking look. He guessed she was picturing the crystal paperweight in her head, and remembering how—
“No,” she said. “I don’t think so. Because the colors change if you tilt it, and they wouldn’t do that if it was stained glass. The cruet set on the sideboard is stained glass, and it's always red, so matter how you look at it.” The professor nodded.
“So— if the paperweight is clear, what makes the colors?” The little girl frowned again.
“Just a minute, I’m going to go get it so I can look at it while I’m thinking.” She jumped down from her chair and scampered away. Prof. Barker resumed coloring, humming to himself as he worked.
Debra’s voice drifted from a window in the house:
“If there’s no Bureau of Fish, Game and Wildlife in this state, do we try the Department of Health, or the American Scenic and Historic Preservation Society?”
“How about the State Department of Environmental Conservation Police?” came her father’s reply.
Angela returned, bearing the paperweight in both hands. She lifted it and set it carefully on the edge of the card table before squirming her way back up onto the chair. Barker reached across the worn baize surface and slid the paperweight to the center of the table, between them.
“What do you notice about it? Besides the color.”
“It was heavy to pick up and carry.”
“That’s because it’s crystal —lead glass— not regular glass. Adding lead makes the glass easier to cut and polish. Gives it a higher index of refraction— that means, it makes it shinier,” he added.
“—and is the shininess what makes the colors?” Angela asked, interested, but also politely nudging the conversation forward, as she’d seen her mother do when someone took too long to get to the point.
“Not quite.” Lionel paused, wondering how to condense Newton for a six-and-a-half-year-old (and without veering off into Einstein). “All the colours we can see,” he said, “are light, at different wavelengths.” He hesitated, casting about for an analogy based in one of Angela’s interests. If he compared colours to radio frequencies, she’d ask why a rainbow wasn’t a cacophony. What a bloody mess he’d got himself into, just trying to describe the shimmer of fish scales. “The baize on this table looks green, because when the sunlight hits it, it absorbs all the light that isn’t green, and only the green light bounces back for our eyes to see.”
Angela stroked the surface of the table-top.
“Clear materials,” Lionel went on, “like glass, or water, are clear because the light passes through them. But sometimes they let more of some colors through than others. And if the clear material is a certain shape— like the angles on that paperweight —it disperses light— er, it sorts it out into the spectrum of different colours.” The little girl tilted her head.
“Oh,” she said. “Why didn’t you say a spectrum was the same thing as a rainbow?”
All of a sudden, she reminded the professor very much of her father. He pulled out his handkerchief and mopped his brow, slightly startled by the relief he felt at seeing something of Noah in the child. Lionel had never doubted the attachment between Angela and her father; Noah wouldn’t care what anybody thought; and Debra could silence gossips with a polite, chill glance; but the little girl was at school now, old enough to overhear things. At least she didn’t not look like Noah; her dark hair could have come from him. Most gossip, Lionel hoped, would be about her slightly premature birthday, and not about a troubled young woman who had—
“So? Tell me about the fish scales.”
“Eh?”
“The fish scales you were talking about earlier, before we went on to this. Do they reflect colors, or do the colors go through them like the crystal paperweight?”
“Hullo, you two— holding a seance?” Noah had come out on the verandah, followed by Bobby and Beelzy. “Anna’s made up a pitcher of lemonade. Darling, be careful you don’t pinch your fingers in the table-leg bracket.” This last comment was to Angela as she gripped the edge of the table to swing herself down from her chair. Landing safely, she looked back up at Lionel:
“Are you coming? You can tell me about the fish scales in the kitchen.”
“Noah, dear boy,” sighed the professor as he got up from the table, “children are exhausting. I don’t know how you and Debra do it.” He picked up the paperweight and handed it to his friend.
Ahead of them Beelzebub, Angela, and her little brother ran towards the house, almost neck-and neck until they reached the back porch, where the four-legged creature bounded up the stairs, the girl climbed them more sedately, and the toddler laboriously made his way up by holding the balusters that supported the handrail too high for him to reach. The analogy I needed, Lionel thought.
“Something funny, old chap?”
“Just l’esprit de l’escalier.”
