In those days, a transatlantic voyage could be dangerous.
当時は大西洋横断の航海は危険なこともあった（◆過去の可能性）
in those far-off days
昔々
in thousands
いく千［万］も
in thrall to ...
…に捕らわれて
in time of peace
平時に
In time writing became a habit with him.
やがて書くことが彼の習慣になった
in times (long) past
（大）昔に
in top gear
トップギアで；最高潮［たけなわ］で
in trade for ...
…と交換に
in transition
過渡期で
