Weather Barometer or Thermometer (Mercury)
These devices contain more mercury than consumer devices and may only be carried by a representative of a government weather bureau or similar agency in carry-on baggage.
The individual must advise the airline of the presence of the mercury barometer or thermometer in the carry-on baggage.
The thermometer must be transported in strong outer packaging having a sealed inner liner or bag constructed of strong, leak-proof and puncture-resistant material that is impervious to mercury and will prevent the escape of mercury from the package in any position. See FAA regulations