Sonic wrench

The sonic wrench was a sonic device used by the First Doctor during his time as a student at the Prydonian Academy on Gallifrey. On one occasion, when fellow Academy student Vansell broke his leg during an attempt to climb Mount Cadon, the Doctor used a sonic wrench and two lengths of twine to create a time bubble to accelerate the healing process and repair Vansell's leg within minutes. (AUDIO: Devil in the Mist)