Excise vigilance, the trader occasionally defrauded; but owing to the great heat of the arch, and the usual Excise securities, the revenue was, on the whole well secured at the lears. Had the lears or kiln been the only departments of the works under Excise survey, the manufacturer would not have been so much inconvenienced. The surveillance of the pots was his chief annoyance, since it required endless trouble, and subjected the manufacturer to danger of Exchequer prosecutions. To throw into the pots ever so small a piece of metal, during the working, incurred a penalty of fifty pounds for every offence. Neither plate Glass nor bottle Glass manufacturers were subject to the surveillance of the pots: this made it exclusively injurious to the flint Glass makers, and was almost a prohibition of alteration of tint, or experiments, and consequent improvements.

It is a matter of astonishment how Flint Glass works existed at all under such a concentration of commercial and manufacturing hindrances as were imposed by the Excise regulations; happily, the incubus exists only in reminiscence.

To return to a few of the curiosities of Annealing. Coke, as has been stated, is the best fuel for this process: it is the most steady and uniform in its calorific powers. Oven-burnt coke is stronger and much more lasting than gas coke; another advantage is, that it is the most free from carbonaceous fumes, or smoke. Fluid Glass need not, therefore, be tinted in excess, only a minimum quantity of manganese being in such case necessary. If coal be used, the smoke, acting by its carbon upon the Glass, will render colourless the