He now gave a good deal of time to physiological study, turning to his old subjects with the vigour of a younger man, and entering with the deepest interest into the discoveries of later science. He did this with a view of bringing his early book, 'The Philosophy of Health,' which at the time of its publication had made so much mark, up to the standard of modern knowledge; and though he did not live to complete this task, the reading for it gave a living interest to those years of quiet country life. He had also much satisfaction in writing and publishing a pamphlet called 'Results of Sanitary Improvement,' based mainly on the experience obtained in the "Model Dwellings" for the working classes, of which he had been the originator. This pamphlet, coming as it did before many influential men throughout the country, spread the good news of progress far and wide. A further instance of the fruit of his labours was afforded him by his visit to Edinburgh, in November 1855, when he lectured on his own subject, "Epidemics," at the Philosophical Institution, where a brilliant reception and distinguished audience awaited him.[24] I have a vivid recollection of his pleasure in the beauty of Alnwick as we journeyed north--of its old castle's warm grey walls, its lovely woods and clear running streams, during a sunny Sunday which we passed there,--the gold and russet tints of autumn shining out against a perfectly blue sky; and I also remember the satisfaction he had in hearing from the Mayor, who took us round the town, of the pure water and good drainage lately introduced. Alnwick was, I believe, one of the first places which adopted the sanitary measures advised by the General Board of Health, so that here he had the gratification of seeing some of the great reforms practically carried out. As I am recalling the various sources of comfort which came to my grandfather during these years at Weybridge, I must mention the great happiness which arose from the opening out of the lives of two of his granddaughters, Miranda and Octavia Hill; for it was at this time that they--at the ages of nineteen and sixteen--took the responsibilities of their lives upon themselves, and began the great and good works which they have since carried to such wide issues. In his retirement, letters of appreciation and sympathy reached him from many of the public men with whom he had worked, expressing in various ways that which Lord Shaftesbury, who knew him as well as any, gives as his own feeling when writing to a mutual friend:-- "I have known Dr Southwood Smith well, having sat with him during four years and in very trying times at the Board of Health. A more able, diligent, zealous, and benevolent man does not exist. No work ever seemed too much for him if it were to do good. His great services will not, I fear, be appreciated in this generation."