A suitcase weighed at 22.4 kilograms in a hallway on Tuesday morning registered 24.1 kilograms at a check-in desk ninety minutes later, with nothing added.

“I weighed it twice,” said traveller Marguerite Delahunty. “I stood on the scale. Then I stood on the scale holding it. That is mathematics.”

The Institute for Transferred Mass has documented the discrepancy for eleven years without resolving it.

“Every bag gains between one and two kilograms in transit to the airport,” said Dr. Emrys Kavanagh. “We have never observed a case of a bag becoming lighter.”

Delahunty responded with the standard remedy, performed at the desk in full view of a queue: opening the case, removing three items, and putting them on.

She checked in wearing two jumpers and a coat, in July, and carried a pair of boots by hand as though they were unrelated to her.

Institute research indicates the manoeuvre removes an average of 1.6 kilograms from the bag and adds it to the traveller, where it is not weighed and is therefore not real.

Delahunty removed the jumpers eleven metres past the desk and carried them, in her arms, for four hours.