CONCORD (AP).- A New Hampshire dealer is auctioning an 1878 letter from Alexander Graham Bell to his parents instructing them to ground the telephone he invented by running a copper wire from their house to the duck pond.

The seven-page letter contains two drawings by Graham of the phone and how to run its elaborate wiring system to avoid harm from lightning strikes.

Bell was responding to a letter from his parents telling him about how a lightning strike had damaged their wiring between several poles. Bell writes that he was "quite troubled" by the news and proceeds to instruct them how to avoid such an incident in the future.

"If you have good connection with a permanently moist stratum of earth, you need never fear lightning and your posts will be safe," Bell writes. His drawing shows a long strand of wire running to a rectangular box, above which is written, "Bury in duck pond."

The letter is more than a tutorial on how to ground his new invention.

He opens with "My dear Papa and Mama" and tells them their new granddaughter is developing into "a healthy-fat-nice-looking baby with tremendous eyes." He describes family friends they visited. He signs the letter, "Your loving son, Alec"— a nickname used only by the family.

The letter is dated June 10, 1878, and was written just two years after Bell obtained the patent on the telephone and made his first call to his assistant, Thomas Watson.

The Scotland-born inventor and his family moved to North America in 1870 and settled at Tutelo Heights near Brantford, Ontario. Bell moved to Boston the following year, where he taught the deaf and later became a professor at Boston University.

Bobby Livingston, vice president of Amherst-based RRAuction, says the letter is especially valuable because of Bell's detailed discussion and drawings.

"It's comparable to Edison sketching the light bulb," Livingston said. "When you see Alexander Graham Bell in his own hand draw out a functioning telephone and where to put the circuit breaker so it doesn't blow up when it gets hit by lightning, it's historically significant."

"It's magical for people like us," he said.

Livingston said the letter is owned by a collector he frequently does business with but didn't know how the collector came to possess it. RRAuction specializes in autographed memorabilia.

Livingston said online bidding for the letter topped $17,000 on Thursday. He said he expects that bidding could reach as much as $80,000 by the auction's end on Jan. 18.


Copyright 2012 The Associated Press.