Starting in November of 1907 the strip was called A. Mutt, before a year was out Jeff would be introduced and the strip would be changed to Mutt & Jeff for the rest of it’s 77 year run.
Before Helium, Hydrogen was used to inflate lighter than air objects such as balloons, blimps, and dirigibles. However, Hydrogen is extremely flammable and dangerous. It was the cause of the Hindenburg disaster in 1937, killing about 36 people.
@Linguist
Chalkie’s “flat” is on the first floor. Which is one floor up from the ground floor.