During this period his work steadily continued to improve. He invented a secret process for giving permanent brilliancy to his ink. He gave the greatest attention to the design and layout of his books, proportion in the matter of margins and the like, and to presswork. This last was doubly important because of his determination to improve the process of illustration. Of course, the modern processes were not then in use. Black and white was done either from wood blocks or steel and copper plates, and color work was done by the use of solid color on blocks. In order to secure better results in black and white, Whittingham invented the over-lay process. Some of his work in color was the best ever produced by the methods which were then known. An indication of the resources of the establishment may be gathered from the story of the production of his British Poets, sets of which may still be occasionally bought in old book-shops. The design for the series was planned in 1819. It was shortly announced that they were to be published on a given day in 1822. When the day came the whole set was published as announced. It consisted of one hundred royal 18mo volumes, illustrated. Five hundred sets were printed, making a total of 50,000 volumes. Shortly after this the younger Charles Whittingham, nephew of the elder, appears upon the scene. He was his uncle’s apprentice and became his partner in 1824. The partnership lasted for four years and was apparently not a very harmonious arrangement. The elder Whittingham, like many strong and successful men, was masterful and was not disposed to share either power or responsibility. The young man, although having no occasion to complain of any unfairness, felt that although nominally a partner he was really merely an employee. In 1828 he left the Chiswick Press and set up for himself in London. He continued in business there for ten years and then his uncle, who was now old and in failing health, called him back to take charge of the Chiswick Press. In spite of the fact that their partnership had not been satisfactory, the old man doubtless realized that his nephew was the only man in England who was competent to continue the business which he had built up with so much toil and in which he took so much pride. From this time until the date of the death of the elder man the younger Whittingham was the moving spirit in the establishment. After the death of the elder Whittingham the plant was moved back to London without change of name.