emerged from the cupboard with a pair of candles and a box of matches. ‘Last time he went near it, it caught fire twice and burnt off one of his eyebrows.’
‘Oh, OK,’ said Tom. ‘What are those?’
He was pointing at a helmet with a pair of binoculars strapped to it.
‘They’re night vision goggles,’ Mrs Nightingale said. ‘I found them at the back of our wardrobe. I thought they might help your father fix the generator but naturally he left them behind.’
‘Brilliant!’ exclaimed Tom. He grabbed the helmet and slid it on to his head, fiddling with the chinstrap.
‘You’d better not break them before I’ve had a go,’ Sophie said.
Tom was squinting through the binoculars.
‘You can see everything!’ he exclaimed. ‘And it turns everyone into a Martian. Rex and Eric have gone bright green. But, you know, that’s kind of cool as well.’
He swung around, narrowly avoiding whacking Sophie with the binoculars.
‘Mum, Grandad was talking about animals that wake up at night,’ Tom said. ‘Is this how they see?’
‘In some cases,’ said Mrs Nightingale. ‘What happens is, those goggles magnify all the available light. There’s infrared light coming from the other side of the canal out there, but it’s too dim for us to see just with our eyes. But when you put those goggles on, they take all those tiny points of light and make them much, much brighter.’
‘So that’s what nocturnal animals do?’ Tom asked.
‘Some of them,’ said Mrs Nightingale. ‘Take owls, for instance. Their eyes are huge – they take up most of their skull. In fact, their eyes are so big that they can’t even move them. That’s why they have to twist their heads around.’
‘Wow,’ said Tom.
‘In those huge eyes,’ Mrs Nightingale went on, ‘they have these amazing cells that can pick up the tiniest dots of light. We have them too, but they have ten times as many – which means they can see a hundred times better than us at night.’
‘Wow,’ said Tom again. ‘And is everything green for them as well?’
‘No, that’s just those goggles,’ said his mum with a smile.
‘It must be my turn now,’ complained Sophie.
Mrs Nightingale nodded. ‘Give them to your sister, Tom.’
Tom groaned and took the helmet off.
Sophie handed Eric to her mother and fastened the helmet chinstrap. Mrs Nightingale returned the rat to his cage and then came back to the living room.
Tom had been thinking.
‘I wish I was a nocturnal animal,’ he said.
‘Hang on,’ Mrs Nightingale said. ‘Not all nocturnal animals have adapted like owls. Think about bats or moles. Their vision has got worse, not better. Mind you, their other senses have developed to compensate.’
‘Oh yeah, Grandad said that,’ Tom said.
‘Moles are my favourite,’ Mrs Nightingale said. ‘They have an amazing sense of touch. They can sense the tiniest vibration in the soil around them.’
‘Cool,’ said Tom. ‘Being a human is rubbish at night-time, that’s for sure.’
‘Mum, look, over there!’ Sophie said, pointing at the window and squinting through the goggles at the other side of the canal.
‘We can’t see anything, can we?’ Tom said, rolling his eyes.
Sophie pulled off the helmet and handed it to her mother.
‘Something’s fallen in the canal and it can’t get out,’ Sophie said. ‘It looks like a puppy.’
Mrs Nightingale looked through the binoculars. She saw a small mammal, scrabbling at the sides of the canal, desperate to find a foothold in the brickwork.
‘It’s a young fox,’ said Mrs Nightingale. ‘It must have misjudged a jump. Foxes are good swimmers, but it looks like this one’s struggling.’
‘We’ve got to help it,’ said Sophie.
‘Sometimes it’s best not to interfere with nature, Sophie,’ said Mrs Nightingale.
‘But that’s your job, isn’t it?’ Sophie protested. ‘Vets interfere with nature all the time.’
‘Hmm,’ said Mrs Nightingale. ‘You