"Robert A. Heinlein - The Man who sold the Moon (collected sto" - читать интересную книгу автора (Heinlein Robert A)

for short wave broadcasting. The frequency of vibration depends directly on
the way the crystal is cut. There is a simple formulaтАФтАЭ He stopped, and
took down a thick India-paper handbook тАЬHmmтАФyes, here it is. For quartz,
every millimetre of thickness of the crystal gives one hundred metres of
wave length. Frequency is, of course, the reciprocal of wave length.
Tourmaline has a similar formula for shorter wave lengths.тАЭ
He continued to read. тАЬThese crystals have the property of flexing when
electric charges are applied to h them, and, vice versa, show an electric
charge when flexed. The period of flexure is an inherent quality of the
crystal, depending on its geometrical proportions. Hooked Into a radio
transmitting circuit, such a crystal requires the circuit to operate at one, and
only one, frequency, that of the crystaLтАЩ ThatтАЩs it, kid, thatтАЩs it! Now if we can
find a crystal that can be cut to vibrate at the frequency of visible light,
weтАЩve got itтАФa way to turn electrical energy into light without heat losses!тАЭ
Mary Lou cluck-clucked admiringly. тАЬMamaтАЩs good boy. Mama knew he
could do it, if he would only try.тАЭ
Nearly six months later Douglas invited his father up to the laboratory to see
the results. He ushered the mild, silver-haired old gentleman into the
sanctum sanctorum and waved to Mary Lou to draw the shades. Then he
pointed to the ceiling.
тАЬThere it is, DadтАФcold lightтАФat a bare fraction of the cost of ordinary
lighting.тАЭ
The elder man looked up and saw, suspended fr├йm the ceiling. a grey
screen, about the size and shape of the top of a card table. Then Mary Lou
threw a switch. The screen glowed brilliantly, but not da7zIingly, and
exhibited a mother-of-pearl iridescence. The room was illuminated by
strong white light without noticeable glare.
The young scientist grinned at his father, as pleased as a puppy who
expects a pat тАЬHow do you like it, Dad?
One hundred candle powerтАФthatтАЩud .take about a hundred watts with
ordinary bulbs, and weтАЩre doing it with two wattsтАФhalf an ampere at four
volts.тАЭ
5
The old man blinked absent-mindedly at the dispily. тАЬVery nice, son, very
nice indeed. Fm pleased that you have perfected it.тАЭ
тАЬLook, DadтАФdo you know what that screen up there is made out of?
Common, ordinary clay. ItтАЩs a form of aluminum silicate; cheap and easy to
make from any clay, or

ore, that contains aluminum. I can use bauxite, or cryolite, or most anything.
You can gather up the raw materials with a steam shovel in any state in the
union.тАЭ
тАЬIs your process all finished, son, and ready to be patented?тАЭ
тАЬWhy, yes, I think so, Dad.тАЭ
тАЬThen letтАЩs go into your office, and sit down. Fve something I must discuss
with you. Ask your young lady to come, too.тАЭ
Young Douglas did as he was told, his mood subdued by his fatherтАЩs
solemn manner. When they were seated, he spoke up.
тАЬWhatтАЩs the trouble, Dad? Can 1 help?тАЭ
тАЬI wish you could, Archie, but Fm afraid not. Fm go.. ing to have to ask you