Thomas was the fourth child of a family of seven. His mother possessed a singularly sweet and beautiful disposition; his father, much given to hobbies, was stern and unbending, and he himself combined an almost womanly gentleness with a quiet determination that unflinchingly faced all obstacles. With a high sense of personal honour, unassuming and even-tempered, he was only roused to anger by acts of oppression or wanton cruelty. Then his indignation, though not loud, was very real, and he acted with a promptitude which would hardly have been expected from his usually placid demeanour. A story is told of how one day sitting at table he saw through the window a man belabouring a woman. Without saying a word, he rushed out, pinioned the offender by the elbows and, running him to the top of a steep slope in the street, gave him a kick which sent him flying down the declivity. The incident is recalled merely as an illustration of his practical way of dealing with difficulties which stood him in good stead in many an out-of-the-way corner of the world when contending with obstacles caused either by the perversity of man or the forces of nature. He never carried fire-arms even when travelling in the most unsettled districts, and his firm but conciliatory manner overcame opposition in a wonderful way. In ordinary life he was the kindest and most considerate of men, and his transparent sincerity made friends for him everywhere. Nor was he ever happier than when assisting others in those pursuits which occupied his own leisure. The interesting question as to what led Belt to become a naturalist is difficult to answer. "Environment" nowadays accounts for much, but none of his brothers--and all the family had a similar bringing-up--showed any inclination for what with him became the ruling passion of his life. And yet, in a wider sense, "environment" had probably something to do with it. In the first half of the nineteenth century Newcastle could boast of a succession of field-naturalists unequalled in the country--Joshua Alder and Albany Hancock, who wrote the monograph on British nudibranchiate mollusca for the Ray Society; William Hutton and John Thornhill, botanists; W.C. Hewitson, Dr. D. Embleton, and John Hancock, zoologists; Thomas Athey and Richard Howse, palaeontologists--these, and others like them, were enthusiastically at work collecting, observing, recording, classifying. Fresh discoveries were being made every day; what are now commonplace scientific truisms wore then all the charm of novelty; the secrets of nature were being unveiled, and modern science was entering upon an ever-extending kingdom. Into all this scientific activity Belt was born, and from his earliest years it may be said of him, as in the well-known lines it was said of Agassiz:-- "And he wandered away and away With Nature, the dear old nurse, Who sang to him night and day The rhymes of the universe."