CONCORD, N.H. (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. RR Auction in Amherst, N.H., will close the auction Jan. 18.

The seven-page letter contains two drawings by Bell 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 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 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.

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