It is addressed to the Commissioners for Enquiring into the best system of Railway Communications through Ireland. The document is written in a clear hand and bears evidence to the logical precision and professional ability of the great railway engineer.
i. References to general maps and detailed sections of the proposed lines. These, unfortunately, are not now incorporated in the ms - see Mr Mayhew's letter of 2 February 1929 inset
ii. Brief account of the circumstances leading up to the investigation
iii. Discussion, technical but very interesting, of the comparative difficulties of (a) the Worcester-Carno-Barmouth-Tremadic-Porthdinllaen route (b)the Wolverhampton-Bala-Dolgellau-Barmouth-Tremadoc-Porthdinllaen route
iv. Decision in favour of iii (b)
v. Discussion of a proposed route from Chester to Holyhead, with reference to a possible packet-station to Dublin at Port Wrexham or St. George's Harbour between the two Ormes (he guards himself by the remark that the bay was so styled by some and others) an emphasis on the engineering difficulties presented by the Conway estuary, the two Penmaens, and Penrhyn Park; the belief that building a second bridge over the Menai to be "too great an undertaking to be seriously contemplated", the alternative being to horse the railway carriages, one at a time, over the Suspension Bridge. He casts doubting eyes at Malltraeth Marsh, the solidity of its soil and its capacity to sustain a heavy embankment. In any case, he thinks, a railway from Llanfair to Holyhead would be to the new high road through Anglesey as th arc and chord of a circular segment
vi. Discussion of a proposed railway route from Bangor to Porthdinllaen through Caernarvon, Llandwrog and the park of Glyn llifon. Vignoles is careful to point that the London-Dublin route would be twenty miles longer than the Bala line.
vii. Merits and demerits of the suggested sites for a packet-station to Ireland. Plumps with emphasis for Porthdinllaen
viii. More detailed discussion of the Bala-Barmouth-Porthdinllaen route - surveys, gradients, engineering problems etc. Note, inter alia, his spelling of Wnion as Onion; his proposal to build at Llanelltyd a gigantic viaduct of an unprecedented height. A table of gradients from Porthdinllaen to bala and analysis of the estimated cost of building a railway along this route.