Final answer:
The time traveller first notices that the Morton's are blinded by fire during a catastrophic event, as described in a scene where a château explodes and the surrounding area is enveloped in flames.
Step-by-step explanation:
The time traveller first notices that the Morton's are blinded by fire during a dramatic and catastrophic event where the environment has been engulfed in flames and turmoil.
From the provided excerpts, it appears that the travellers are faced with a sudden, intense inferno that not only blinds them but also causes total destruction. The narrative describes moments where fire consumes a library, a dwelling that a character recognizes as their own home, and other instances where people and nature alike are ravaged by the fiery catastrophe.
Through these vivid and harrowing scenes, the theme of chaos and the powerful, often uncontrollable nature of fire are communicated to the reader. Among these scenes, one describes a château that 'threw itself into the air,' indicating a violent eruption likely caused by fire, which could be a critical moment the time traveller realizes the severity of the blinding fire.