Another suggested mode is that of casting in clay moulds, by a method very similar to that used in the sand process, and resulting in similar peculiarities and variations in the types. Mr. Ottley, who is the chief exponent of this theory, suggests that the types were made by pouring melted lead or other soft metal, into moulds of earth or plaster, formed, while the earth or plaster was in a moist state, upon letters cut by hand in wood or metal; in the ordinary manner used from time immemorial in casting statues of bronze and other articles of metal, whether for use or ornament. The mould thus formed could not be of long duration; indeed, it could scarcely avail for a second casting, as it would be scarcely possible to extract the type after casting without breaking the clay, and even if that could be done, the shrinking of the metal in cooling would be apt to warp the mould beyond the possibility of further use. Mr. Ottley thinks that the constant renewal of the moulds could be effected by using old types cast out of them, after being touched up by the graver, as models. And this he considers will account for the varieties observable in the different letters. In this last conjecture we think Mr. Ottley goes out of his way to suggest an unnecessary difficulty. If, as he contends, the _Speculum_ was printed two pages at a time, with soft types cast by the clay process and renewed from time to time by castings from fresh moulds formed upon the old letters touched up by the graver, we should witness a gradual deterioration and attenuation in the type, as the work progressed, which would leave the face of the letter, at the end, unrecognisable as that with which it began. It would be more reasonable to suppose that one set of models would be reserved for the periodical renewal of the moulds all through the work, and that the variations in the types would be due, not to the gradual paring of the faces of the models, but to the different skill and exactness with which the successive moulds would be taken.[24] {12}