Complex sentence: The W&P directors invited the first tenders for the construction of at the Whitby end of the railway by August 1833 and in October 1834 tenders for the final 8.5 miles (the'central division' of the railway) were invited.
Split into simpler sentences: The W&P directors did not delay and by August 1833 were inviting the first tenders for the construction of the railway, at the Whitby end. It was only thirteen months later that in October 1834 that Tenders for the final 8.5 miles (the'central division' of the railway) were invited.