The navigations were used for transporting barge loads of heavy goods to London. Timber, corn, flour, wood and gunpowder from the Chilworth mills moved north along the canal and then down the Thames to London while coal was brought back principally for gunpowder making and smithery. Other return cargoes included sugar and bark, which was used for tanning. The trade in timber destined for the shipyards on the Thames had been established well before the river was canalised, and in 1664, 4,000 loads of timber were reported to have passed down the river. Much of the timber used in the reconstruction of London after the Great Fire was transported this way. In addition stone for the reconstruction of St Paul’s Cathedral came from the quarries at Guildford. Daniel Defoe, in "A tour through England and Wales", noted very great quantities of timber using the river, which was brought to Guildford from forests in Sussex and Hampshire up to away during the summer months. The Rev. W Gilpin, writing in 1776, recorded that timber was floated down the river, with each load steered by a man with a pole. There was a significant trade in hoops and paper, while Defoe recorded that corn was bought at the corn market in Farnham, to be transported to the mills on the river by boat, and then shipped to London once it had been processed.