The logistical problems of spanning the Firth were numerous, but their solution resulted in one of the greatest engineering achievements of the Victorian era, the Forth Railway Bridge.
The Forth Railway Bridge was an easy feat to tackle in the Victorian Period.  
mnli hypothesis: The Forth Railway Bridge was an easy feat to tackle in the Victorian Period.   premise: The logistical problems of spanning the Firth were numerous, but their solution resulted in one of the greatest engineering achievements of the Victorian era, the Forth Railway Bridge.