made an important discovery for the conversion of sewage into agricultural manure. Filtration from below upwards, he explained, through some appropriate medium, which retained the solids and set free the fluid sewage for irrigation, was the principle of the scheme. "All previous plans," he said, "would have cost millions; mine costs next to nothing." Unfortunately, owing to a slight miscalculation, the invention proved to be impracticable; but Albert's intelligence was unrebuffed, and he passed on, to plunge with all his accustomed ardour into a prolonged study of the rudiments of lithography.
But naturally it was upon his children that his private interests and those of Victoria were concentrated most vigorously. The royal nurseries showed no sign of emptying. The birth of the Prince Arthur in 1850 was followed, three years later, by that of the Prince Leopold; and in 1857 the Princess Beatrice was born. A family of nine must be, in any circumstances, a grave responsibility; and the Prince realised to the full how much the high destinies of his offspring intensified the need of parental care. It was inevitable that he should believe profoundly in the importance of education; he himself had been the product of
